Conference vmszoo::rc

I got a RAM simple cycler from Tower Hobbies for $15.49 including shipping.

It works for Tx and Rx batteries and there are some hidden costs.
It doesn't come with connectors (cause they don't assume Futaba).

It is a simple little circuit board mounted in a little plastic case.
It discharges and set's off a high pitched tone when it is time to remove
the plug.  It won't work on larger batteries such as you might have
for a CAR or an electric plane.  You have to manually disconnect it
when it's time or it will just keep discharging too far.

RAM also makes a model for larger (R/C Car type) batteries.

              _!_
Bye        ----O----
Kay R. Fisher / \
 
==============================================================

    I have a DIGIPACE ram cycler. This unit discharges both the receiver
    and transmitter sperately and records the time of both. When I come
    back from the flying field I put the plane on the unit and determine
    the discharge time remaining. If enough time is left, I can put
    in more flights next time. I also don't have to worry about forgetting
    that the unit is on discharge and thereby damage the unit.
    It's also usefull for finding bad batteries.
    If your batteries are new you can get allong without one. As your
    batteries get older, the risk of a cell going bad increases.
    I saw an ad for a similar unit for less money than the DIGIPACE.

    
    	I also have a Ram Simple Cycler, and have adapted it to work
    for my RC car pack.  (5 cell hump pack)    I will check tonight
    and put in a blurb tomorrow about how I changed it.  (I had help
    from another RC noter, and if he has the info here at work, maybe
    he would be able to put it in today.)
    
    		Brian
    

    Tom,
    I have had a taylar for the last four years. Also comes without
    connectors. The system discharges your batteries, both trans. and
    receiver independtly, and at the right point goes into a charge
    state. Mah that was remaining in your batteries is logged by two
    manual clocks. 
    
    I use mine about once a month on all my systems from a full charge.
    When they start showing 400 to 450 mah i watch them closely. If
    they go below 400 and i can't bring them up i change them out. The
    leftovers along with a radio shack charger make great batteries
    for your camera strobe, kids toys, receiver packs for cars, etc.
    
    They will usually come back for a few months by running them all
    , or close, to the way down and quick charging them a few times.
    I use a MENS charger for that. Sometimes i can get as much as 600
    on a 550 pack doing this..........
    
    Price back then was in the $70.00 range.......
    
    bob
    

    
    	Re: 2 + 3...Ram Simple Cycler.    It can be used for discharging
    the 5 cell (7.2v) packs, by simply adding a 10 ohm resistor to the
    yellow (Rx) lead before attaching to the pack.  I did this by using
    Silicone Gasket goop to mount the resistor to the inside of the
    cover, and I presently use jumper wires to connect it to the pack.
    (Since I don't have the proper connectors yet.)  The other lead
    from the pack goes to the black wire of the Simple Cycler.  Be sure
    to remember that there is a polarity  to follow when doing this!!
    (Hot lead from the battery pack is usually Red.)
    
    		For those who were wondering ~~~~~~.....
    
    			Brian
    

So Tom what kind of battery cycler did you finally get?

About the ACE Digipace - Balsa USA lists them at 88.99 and they come in 3
varieties.
[20/50 ma rx chg]
[50/120 ma rx chg]
[kit] at $75.99

I assume that the kit can go either way.
Which is the correct charge rate? and if say [20/50] is right for planes
then what is the other rate used for?
Is there two digital readouts for capacity or do you flip a switch to direct
the readout for tx or rx?
Is the Digipace the only auto cycle with simultaneous tx,rx cycling or do
they have other models?

About the taylor units

An earlier note said that they independently do tx,rx.  Does that mean
Simultaneously?

Also was stated that they logged Mah remaining by two manual clocks.
What does that mean "Manual Clock"?

The latest Tower add only has one product from Taylor and that is a
Power Pacer 9.6V for $54.99 - is that the cycler were talking about?

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

    Re: .6

    I presently own a DIGIPACE, and find it great for care and feeding
    of my nicads...
    
>[20/50 ma rx chg]
>[50/120 ma rx chg]
>[kit] at $75.99
>I assume that the kit can go either way.

I think the kit (like the CHARGEMASTER by ACE) will permit modication for
either charge rates.

>Which is the correct charge rate? and if say [20/50] is right for planes
>then what is the other rate used for?

They plan on a 10% of rated pack capacity for charging, so if you use 1200mah
packs, then the 120ma version would be used.  Most std flight packs are
500mah to 550mah, therefore the 50ma rate would be used.


>Is there two digital readouts for capacity or do you flip a switch to direct
>the readout for tx or rx?

There is a single multiplexed led display that reads minutes and tenths of
minutes in discharge time.  To see TX or RX, a slide switch is actuated,
for non-destructible readout of either value.  You can calculate your
battery pack's capacity by using the knowledge of its original full capacity
(say 500mah) and how long it took to discharge at the internal rate.

>Is the Digipace the only auto cycle with simultaneous tx,rx cycling or do
>they have other models?

A quick call or look in ACE's catalog could answer that, but I think the
DIGIPACE is their prime cycler.

			-Mike

    Well, let's wake this note up again since the flying season is on
    the wane for many of us.
    
    As I see it, there are 3 choices....  
    
    RAM simple cycler - actually this is just a discharge unit and leaves
    the timing of the discharge to the operator.  Effective but only
    marginally useful for those of us that easily forget and leave the
    house while discharging the batteries.  Also, only one battery may
    be discharged at once.  Price is still around $15.
    
    Ace digipace - LED output of total discharge minutes.  As with the
    RAM, you still need to look at charts/mathmatically figure out how
    good the battery is.  Big advantage here is that at the end of
    discharge, it will automatically switch to charge mode.  Both Tx
    and Rx batteries may be discharge/charged at the same time.
    (is this info correct??  What other features does this have??)
    Price appears to be $80-$90.
    
    Taylor "power pacer" - This unit also allows both Rx and Tx batteries
    to be discharged and charged at the same time.  There are red and
    green LEDs for each so that you know what is going on in a glance.
    It also has a dial readout that shows you the Mah capacity that
    the battery had.  I presume that you can also get this with various
    charge/discharge rates.  Last I hear, you could still get one of
    these for about $55.
    
    None of the 3 have any connectors, so that is a moot issue.  The
    Taylor seems to be the best buy.  I have used both the Taylor and
    the RAM.
    
    Does anyone know how to get in touch with Taylor directly??  I am
    willing to put together a group deal if others are interested. 
    If someone gives me a phone number I will call and find out what
    kind of price break we can get.  I would then post the price and
    ask for participants.
    
    Are there other units that are available that should be considered??
    
    Thanks,
    jeff
    

    I have a cycler from Litco Systems and am very pleased with it.  It
    is their "Multi-Cycle" model and is simialr to the Ace Digipace. 
    However, it uses 2 LCD displays (one for Tx, one for Rx) instead of
    the single LED dispaly of the ACE unit.  They claim the discharge
    time will be retained even in the event of a power failure since
    they use LCD's (they use the batteries you're charging to maintain
    the very low current for the LCD's).

    It's very simple to use:  
        Plug it in to the wall 
        Plug in Tx and/or Rx  (Connectors not included)
        A small LED lights up for each to indicate "charging" and that
            you have made a good connection
        Press a push-button to start the discharge cycle
        The LED's go out and the digital LCD display starts to indicate
            the discharge time
        When the Rx and/or Tx discharges, the LCD displays go blank and
            the charging LED lights up.
        When you want to see the discharge time, press the discharge
            button, read the time and disconnect the batteries.

    I think the current price for the Multi-Cycler is $69.50.  Check
    their ad in Model Aviation or RCM.  Their ads are usually black
    background with white letters.

    Litco Systems
    Box 90
    East Hanover, NJ  07936

                       _____
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                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Caster Oil!! "    
                      |_____/

    I've used an L.R. Taylor Power-Pacer for 6-7 years now and love
    it.  More importantly, I trust it implicitly!  I particularly like 
    the direst mah readout; no math conversion to do to determine battery
    capacity.  I'm not sure whether these are available with various
    charge rates; mine charges at 75mah which I find more than adequate
    for any/all packs I use.
    
    I break all my charger cords and install Deans connectors so the
    cycler can be used on any/all systems I own. I also replace all
    my Rx charging jacks with Deans connectors for the reason stated
    above.  My cycler is interchangeable with all my Rx's and Tx's,
    regardless of brand.     

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    
    I had heard that somewhere's too, although I can't remember where.
    I have yet to hear anyone say what radios are not compatible.  As
    far as I know, all of the popular models of the popular manufacturers
    are fine.  If you can take a ESV reading, you can use a cycler.
    
    Well, your info on trickle charging conflicts with the factory.
    They guy that I talked to seemed knowledgable about batteries and
    seemed to know his product very well.  I tend to think the ad might
    be wrong.
    
    Model 300, for 9.6V transmitters.  I guess I assumed that that was
    OK with everyone.  Again, there are very few that are not 9.6V.
    
    cheers,
    jeff
    

    Jeff, Ken,
    
    JR transmitters cannot be cycled on L.R. Taylor's or anyone else's
    cycler(s).  I can't expound the theory as to why but it has something
    to do with a diode in the battery circuit as Ken alludes.  As I
    understand it, attempting to cycle the Tx _will_ result in grievous
    damage to the pack and/or related circuitry.  For me, this is a
    considerable disadvantage and a reason why I don't fly JR...I want
    to have a way of staying aware of battery condition and this feature(?)
    of the JR Tx prevents that.  I don't know whether or not a similar
    problem exists with the JR Rx pack but I think it applies only to
    the Tx pack.
    
    As far as I'm aware, having used my L.R. Taylor in excess of 6-years
    (during which time I've probably saved 3 or more airplanes by detecting
    battery problems _on_the_ground_), the Power Pacer does not cycle
    down to a trickle charge rate.  If it does, it gives no visual (or
    other) indication of doing so.  I find this to be no disadvantage
    whatsoever and tend to agree with the statement offered by the L.R.
    Taylor rep that this (trickle charging) may actually be harmful
    to NiCads.

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    Al,
    I am not sure what JR transmitter model you are talking about, but
    I have both the Century VII and the Galaxy 8 transmitters and have
    been using the L.R.Taylor cycler on them since the past Winter
    with no apparent problems.  I know you have to be careful not to
    put too heavy a load on the battery, since it is fused.  I do not
    remember the value of the fuse, but it is large enough that the
    L.R.Taylor cycler does not blow it.

		________
	 /	  __|__  
	=========[_____\>
	/	__|___|__/  BREAK A BLADE,
			    Ken    	

    Ken,
    
    Well, I've made the mistake of repeating something from hearsay,
    not personal knowledge.  If you're getting away with cycling your
    JR packs, obviously it _can_ be done.  All I can relate (and what
    I accepted as gospel) is that my buddy, Chuck Collier, who flies
    JR exclusively, has mentioned numerous times that he cannot use
    a cycler on his transmitters.  (He has an Unlimited-8, a Century-7
    and a Computer-8 PCM.)  He's referred to a diode (or some such)
    in the pack as being the reason and has said that JR advises that
    use of a cycler can cause serious damage.  Are you doing anything
    unique or just hooking up and pushing the button like any average
    Joe Scrapmetal might do?
    
    That's all I know and, admittedly, it's hearsay, though it's firsthand
    hearsay.  I merely accepted Chuck's statement(s) as accurate.  If
    incorrect, I stand corrected and apologize if I created/added to
    the confusion.
    
    I believe my other statements regarding standard Tx and Rx voltages
    and cyclers being geared toward these standards to be accurate/true.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o         
      |    Z__(O_\_	(The Desert Rat)

    Maybe ignorance is bliss, and I have something amiss with my
    JR transmitters, but, I just hooked up the cycler and use it on
    the standard charge jack with both my Century VII and Galaxy PCM
    and I have had good luck, except that the discharge level on the
    transmitters does not get down to 1.1 volt/cell.  It only goes to
    about 9.2 volts, which I attribute to calibration.  It seems
    a coincidence that the diode in both transmitters would be shorted
    so that this would work, but that may be the case.

		________
	 /	  __|__  
	=========[_____\>
	/	__|___|__/  BREAK A BLADE,
			    Ken    	

    Eric,
    	How come your cycler didn't tell you that one cell was bad?
    My home brew one checks pack voltage and shuts off when 1.1v/cell
    is reached.  With a RX pack, this is 4.4 volts, so the cycler
    won't even start running if one cell is shorted.  I have caught
    dead cells in one of my packs and in several other people's packs.
    I cycle both my Airtronics and Futaba rigs right through the charge
    plugs on the plane and on the TX.  I would bet that many guys that
    don't check their batteries are flying with a shorted cell either
    in their TX or RX.  In my Airtronics TX, my signal strength is normal
    with one shorted cell.
    
    Charlie
    

    Interesting Ken that you should bring up the diode in the JR radios...
    I had an interesting problem sunday night. I plugged my Century
    VII into the changing jack and the LED went on, then off. I checked
    the transmitter out on a second changed an no light. Oh hell I thought.
    So I opened up the back and for the life of me I couldn't find a
    diode in the charging circuit. It appears that it may have had one
    at one time but that it was replaced in the factory by a wire jumper.
    Tracing the charging circuit back further I found my problem. The
    charging circuit runs directly into a fuse. 3Amp. This had blown.
    I replaced it.
    
    						Tom

    Eric,
    It sounds like the comment to charge with the resistor supplied,
    but the value of the resistor that was supplied was incorrect. 
    The ideal charge rate would be c/10 or 1200/10=120 ma.  I am 
    certain that you are aware of this.  Not knowing the circuit,
    I am not sure what that value would be, but you should be able
    to get the correct value from either JR or maybe by a substitution
    box and finding it empirically, if it can not be done by just ohms
    law.  It sounds like the resistor value that was included was for
    using it with a 2000 ma pack or 500 ma pack.

		________
	 /	  __|__  
	=========[_____\>
	/	__|___|__/  BREAK A BLADE,
			    Ken    	

    Eric,
    	What discharge rate do you use when testing your 1200 Mmah packs?
    Also, just a minor correction:A charger charges in ma, not mah.
    I have been discharging my packs at C/2 on my home built cycler.
    My unit presently can't handle 1200 Mah packs but I plan to upgrade
    it since I am going to get into electrics.  The new 1700 Mah packs
    require more heat dissipation capability in the cycler than mine
    has.
    
    Charlie
    

    Eric,
    	I hear you and agree completely with not trusting older packs
    in a plane.  I find other uses for old cells or ones out of a pack
    that has failed.  I use them to run my electric fuel pump or let
    my kids use them in their walkmans.  I have had a couple of shorted
    cells show up in 3 year old packs.  The corrosion you describe is
    usually due to overcharging which blows the vents.  I guess defective
    seals could cause it without overcharging as well.  Lots of cheap
    chargers like the ones GE sells overcharge the cells if left on
    too long.  A cell should never be left on overnight charge at a
    rate over .1C or 50 Ma for our normal TX and RX packs.  
    	I plan to investigate battery characteristics with different
    charging and discharging this winter.  I want to convince myself
    whether slow charging is really better than fast charging (done
    properly with peak detection).  I always slow charge my batteries
    for planes, but I don't seem to get tremendous battery life.
    I have several packs that now only get about 60% of their maH
    rating.  Their discharge curve seems to have just gotten steeper.
    If I find that fast charging is ok, then I will change over to that
    and charge just before flying sessions rather than overnight as
    I do now.  I'll be sure to put the results of my experiments in
    this note.
    
    Charlie
    

    Kevin,
    
    My friend, yer' playin' Russian Roulette by not cycling yer' packs!
    Not only is it _good_ for the batteries, it gives _you_ the peace
    of mind of _KNOWING_ the condition/capacity of yer' packs.  You
    better get in line for one of the LR Taylor cyclers Jeff ordered.
    I'd absolutely refuse to fly without the cycler's benefits, now that
    I've become used to using it.  I can't imagine how I/we ever got
    along without this device.
    
    I started cycling batteries nearly 15-years ago when the first
    commercial cycler, the "Flite-Life," came on the market.  In the
    time since, I've not lost a single aircraft to bad batteries though
    I've probably averted at least 6-potential crashes by finding bad
    cells/packs on-the-ground which is where you _SHOULD_ find them.
    I'd have to say the two cyclers I've purchased over the years have
    *MORE* than paid for themselves!!!!!!    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

        Trickle charge is anything under .1C, usually in the .01-.03C
        range. While a couple days of this won't hurt NiCads, I still
        don't feel comfortable leaving them at even this level
        indefinitely (like those rechargable appliances with the charger
        bases do). No problem, however, doing this with gell-cells. 

    
    
    	Just a note to plug these chargers........I ordered mine in
    the last batch, and have used it 4 times to cycle my batteries.
    (I bought my radio equipment with a completed plane, and had not
    used it since due to my just starting in the hobby.  So, the radio
    gear and batteries sat untouched for about 8 months.)
    	After I got the charger, I started cycling...and guess what?!!
    You got it, the state of the batteries was pity-full!
    	Now for clarity, I should tell you that I had charged the TX
    and RX both with the factory supplied charger about a week prior
    to trying to cycle them.  When I hooked up the cycler, the Tx indicator
    would not lock on. (When discharging, the red LED should light and
    remain on after the test button is pushed.)  Mine would stay on
    while the test button was pushed, then go out when it was released.
    A quick check of the directions told me that the Tx pack had a cell
    that was Below the 1.1 volt level!  So, I first charged the Tx pack,
    then discharged them both together.
    	The following are the readings I have gotten so far from the
    charger "timers" that read the condition of the packs:
    
    			    Tx               Rx
    
    	1st discharge       175ma	    250ma
        2nd discharge	    375ma	    475ma
    	3rd discharge       375ma	    475ma
    	4th discharge	    400ma	    500ma
    
    	This proves to me that a Good Quality cycler is a MUST for aircraft
    use.  If I had relied on the factory charger alone, and tried to
    fly my plane, there is no doubt in my mind that I would have had
    a fly-away or a crash.
    
    	So!!!  The purpose of this long winded note is to tell all you
    procrastinators that you Need a cycler....it is not a convenience,
    it is a necessity!
    
    	(I imagine not everyone leaves their radio equipment untouched
    for months like I did, but still....do you _Really_ want to take
    the chance with you pride and joy??)
    
    	Brian_who_now_appreciates_his_cycler!!
    
    
    

    
    	Correction!!!!    to reply .63, I purchased the equipment
    in July of 1987...that makes it about a year and a half that
    those battery packs had been left alone, not 8 months as I said.
    Considering that, it's suprising they weren't completely useless!
    	
    
    	Brian
    

>    	Correction!!!!    to reply .63, I purchased the equipment
>    in July of 1987...that makes it about a year and a half that
>    those battery packs had been left alone, not 8 months as I said.
>    Considering that, it's surprising they weren't completely useless!

Brian - your observation is correct.  Nearly everyone who first cycles
their batteries is shocked at how bad they were.  In your case and most
others the batteries are not malfunctioning - just need cycling to bring
them back to max capacity.  You don't need to wait 18 months to see the
same results.  If you have been flying and charging all summer then your
batteries need cycling to eliminate the memory effect that has built up.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
================================================================================
    

    BRIAN, KAY,
    
    Both yer' observations are dead on the "money."  I cycle my packs,
    just for drill and to have the peace of mind of knowing their state,
    anytime they've sat for 6-weeks or so.  Also, if flying heavily,
    I cycle every 6th-8th flying session to break any 'memory' that
    has developed as a result of not exhausting the packs' capacity
    before giving them a complete recharge.                             
    
    Brian, I'd still be suspect of the Tx pack that's showing only 400ma.
    If further cycling doesn't pump the pack up to at least 500ma (I'm
    sure it's a 550ma pack), I'd dertainly replace it.

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    I have been giving trickle charging some thought myself.  I find
    that I often end up charging my batteries and then not flying due
    to weather conditions then repeating this a week later.  I am thinking
    of building a trickle charge station to keep my TX and RX packs
    on constant charge so that I don't have to charge them unnecessairly.
    From what I've read, 5 ma is a good number to keep a fully charged
    pack peaked without hurting anything.  A normal overnight charger
    puts out ten times this.  I don't think that it's a good idea to
    leave your fully charged batteries on normal charge for more than
    a day.  If anyone has any comments on this, please add them.
    
    Charlie
    

    Eric,
    	How does the auto trickle work?  Is it timed or sensed somehow?
    WHat do they use for the charge and trickle currents?  I'm in the
    process of making my own charger and I'm trying to decide what features
    to add.  Right now, I'm leaning toward doing either a timed charge
    with a switch to trickle or just a manual switch to select charge
    or trickle.
    
    CHarlie
    

    Charlie,

    I'll bet it uses Peak detection to trip to the lower charge rate.
    Peak detection works great for high-rate charging my flight packs,
    but there is no reason why it wouldn't work just as well at a much
    lower rate when charging radio packs.  The only problem I could
    forsee is that due to the lower charge rate, the rate of change of
    voltage as you approach peak is probably slower, but if you are
    looking for the change in slope with your microcomputer and an A/D
    converter, that should not pose any problem for you.

    Randy

    Randy,
    	I don't think that you could reliably detect a peak at the normal
    50 ma charge rate.  I bet that the thing is a timer of some sort
    designed to give you 12 hours at normal rate and then drop in a
    resistor to reduce the rate.  I've been getting some interesting
    charge voltage curves with my micro charger interface.  I have been
    tripping the stop at 10 mv per cell below the peak and it seems
    to work well.  The cells charge at a pretty constant voltage and
    then the voltage shoots up a couple of minutes before peaking out
    and starting to drop.  I think that you could shut off early if
    the rate if increase was sensed instead of the drop from peak.
    	By the way, peak charging of a battery pack only works well
    if the cells are MATCHED in capacity and state of discharge when
    starting the charge.  THis suggests that you should trickle charge
    your pack if you haven't used it for a while to fully charge all
    cells.  I cycled one pack that had sat around and the first charge
    cycle shut off way early because one cell was still fully charged
    and a couple others had self discharged.  This resulted in overcharging
    a couple of cells more than normal and not fully charging the others.
    A trickle charge and another cycle showed normal results.  I plan
    to trickle charge my high discharge packs when not in use to keep
    them balanced.  
    	Some people fully discharge high discharge packs with a load
    such as an auto headlamp before charging them.  This can really
    ruin a battery if they are not equalized by reverse charging some
    of the cells.  If you can get in and load each cell individually,
    it is ok to fully discharge a battery before charging.  It's also
    ok if the pack is well matched.  I wouldn't do it regularly though.
    THat also goes for fully discharging a car of plane.  Never do this
    on purpose since battery life will suffer if the pack isn't matched.
    
    Charlie
    

    Charlie,

    On the subject of charge/discharge of packs with unmatched cells.
    I typically "Equalize" my packs once every 6 to 8 charges.  This
    entails a trickle discharge of the pack, followed by an overnight
    trickle charge.  A while ago I read something about the way packs
    behave when they are fast charged and then highrate discharged.
    You are absolutely correct.  Because no cell is an exact match for
    any other, all cells discharge (under load or otherwise) at
    different rates.  This could well leave you with some cells
    completely "flat" while others of the same pack have substantial
    charge remaining.  If you peak charge a pack in this condition,
    you invariably end up with the charge cycle terminating when the
    cell with the highest starting charge reaches peak.  This leaves
    some cells, potentially, well below maximum charge, a condition
    which can have a MAJOR effect on an electric planes ability to
    fly.  Most people who are heavily into racing cars do the same
    thing I do for my planes.  You can really see a difference, since
    a plane flown on a trickle charged pack typically flys for a
    longer time than the same plane, on the same pack, after a few
    fast charges.  Also, the "deep" cycle of the pack is supposedly
    healthier for the cells, erasing any memory the cell may have
    started to develop, as well as helping to prevent internal shorts.

    Randy

    Randy,
    	I agree with you but I can add that peak charging an unequalized
    pack can be worse than just short charging the cells that were more
    fully discharged since the peak detector is looking for a peak that
    is generated when all the cells go into overcharge.  If only one
    cell goes into overcharge first, the peak detector will not stop
    the charge until that poor cell gets really overcharged and the
    voltage drops enough to simulate the whole battery peaking.  And
    to make matters worse, the other cells are still continuing to increase
    in voltage thus canceling out the peak/drop on the overcharged cell.
    The bottom line is that the overcharged cell will overheat and could
    be damaged.  I strongly support your trickle charge technique.
    I plan to do that with my batteries and only quick charge at the
    field between flights.  My night time charging will be at .1 C rate.
    
    Charlie
     

    Ken,
    	A 15 hour charge is usually done at .1C or 50 Ma for a 500 mah
    pack.  This is not a trickle charge that should be done indefinately
    but what should be called an 'overnight' charge.  It does not hurt
    (acording to the battery data sheets) to overcharge at this rate
    so you can leave it on longer than 15 hours.  However, if you have
    a desire to keep your batteries fully charged over weeks or months,
    you should use a trickle charge of .01 to .02 C which would be
    5 to 10 ma on a 500 mah pack.  There are several chargers on the
    market that have manual switches to switch to trickle charge and
    I think that ACE has one that does it automaticaly.  Most cyclers
    are not really designed to be especially good chargers since 
    chargers come with radio systems.  They are primarily focused on
    the discharge function with timing capability to keep track of the
    discharge time to determine battery capacity.  
    	By the way, I talked to a guy at S & R Batteries about charging,
    storage, and general care and feeding of nicads.  He said that the
    best way to store nicads for a long period of time (> 1 month or
    so) is to fully discharge the cells.  This was a big suprise to
    me and I don't know whether I fully accept this as fact.  He seemed
    to know what he was talking about.  He also said (and I fully agree
    with this) that the full discharge can only be safely done by loading
    each individual cell with a 1.5 volt flashlight bulb.  NEVER do
    this by connecting a load to the whold pack as you will reverse
    charge some of the cells if you do.  I would think that either
    periodically cycling and recharging overnight or continuous
    trickle charging would be the way to store them.  If I find out
    more, I will let you know.
    
    Charlie
    

re  Note 852.0            Build your own RAM SIMPLE CYCLER????? 
    
    I would expect that sometime in the next several months one of us will
    enter a circuit for a cycler more capable than the Taylor or Digipace.
    
    For a self-stopping discharger see Electronic Design News (called EDN
    in your DEC library) 9/5/85 pg 301.  Where it refers to an event
    recorder, put in a Radio Shack relay (12v coil, 1 Amp @110v AC contacts, 
    NO [="normally open"]) and control an ordinary electric clock with it. 
    

        I seem to be cursed with packs of various voltages for different
        applications. Anyone know how to modify one of these for different
        pack voltages, so that the readout is correct. Ideally, I'd like
        some sort of switch on the unit to select from 4.8, 6.0, 7.2, 8.4,
        9.6, and 12.0, perhaps the first three on the RX side, and the
        last three on the TX side. I'm not worried that the charge rates
        won't be right for standard times, as I can compensate for that by
        charging for longer times. I just want accurate readouts for any
        pack I might test. Thanks. 

>        applications. Anyone know how to modify one of these for different
>        pack voltages, so that the readout is correct. Ideally, I'd like

Not sure what you final application is but for my flight line battery 
condition monitor (a cheap old LED digital voltmeter) I made up a resistor
load that had two resistors in series for the transmitter and one for
the receiver - I ran the wires form the two resistors to the Futaba
transmitter charge plug but I tapped the center of the resistors for
the voltmeter.  So voltmeter readings for a good 9.6 volt battery are
4.8 volts.  Same glob of resistors has a plug from a single resistor
to a Futaba receiver plug.  In this case the 4.8 volt pack reads 4.8 volts.

You could make packs of precision resistors for all your voltage combinations
and just label the connectors as to what pack they go to.  Always expecting
4.8 volts means good.  In the case of a JR transmitter I just plug in the
Futaba transmitter plug and the voltmeter now reads -4.8 volts (Don't
do that with your charger!).

Was this at all close to what you were asking?

Bye          --+--
Kay R. Fisher  |
---------------O---------------
================================================================================

        re: .90
        
        Nope, I think you missed it. 
        
        Measuring voltage is no problem. I have a DMM that does quite well
        at that, as long as I know what is GOOD and what is BAD. 
        
        I want to modify the L.R.Taylor cycler to cycle packs at other
        than the standard 4.8/9.6v combinations. The instructions indicate
        that they are available in different setups, but I guess this is
        the standard. It can't be more than changing the RIGHT resistor,
        and it shouldn't be too hard to have a rotary switch to select one
        of 3 resistors for the discharge rates. I just need to know what
        is the right resistor to mess with. The beast didn't come with a
        schematic; I was hoping someone had looked at this mod already. 

re Note 126.93  POBOX::KAPLOW     Taylor mod at other than standard 4.8/9.6v 
    
>>      It can't be more than changing the RIGHT resistor, ....
>>      I was hoping someone had looked at this mod already. 
    
    Sorry, but there *is* more to it than the resistor, namely the portion
    that senses when the discharge is done and then switches over to charge
    the pack.  However, in spirit you are right; it is straightforward to
    design and build an N-cell cycler for overnight charging.  That was
    what I had in mind in reply 126.82.  I just haven't done it yet. 
    
    The device I have in mind has two rotary switches, two LED's, a phono
    jack for generic output connections, a what-to-do switch, and a readout
    for the mAh.  One rotary selects the number of cells (from one to ten),
    and the other selects the original mAh capacity of the pack (from 500
    to 15,000). The device would discharge the pack at C/1, display (until
    reset) the drained mAh, recharge at C/10 for 16 hours, and then trickle
    at C/20 forever.  Comments are requested.

    Thanks for the cycler, Jeff. It works great on my flight packs,
    but I seem to be one of the poor folks with a Century VII transmitter
    that doesn't like cyclers. I re-read all previous notes about this
    problem and noted that the charge socket was reversed (center pin
    = -ve), but I also took the TX apart and could not find a diode
    anywhere. There was a wire link on the small charger socket board
    like Tom's. My symptom now is that I have a reasonably charged TX
    battery that refuses to discharge via the cycler...
    
    Anyone got any fresh insights or ideas??
    
 	------+------
 	   (Z[]>=====X  Jimi.
 	 `--'-`---

    Thanks for the advice Eric. Re your item (1), I followed the
    instructions for the cycler about "...before plugging the cycler
    into the wall socket connect it to the batteries. If the green LED
    lights then the plug polarity is reversed...". I had assumed (!) that
    I should connect the cycler +ve lead to the red lead on my JR charge
    plug, however as noted in [.-many] and from the test described above,
    it appears that the JR uses a -ve center pin connection on the charger
    jack.
    
    I think I will follow your example of adding a 1/8" jack connected
    directly to the TX pack. Having seen the good effect this cycler
    has on my flight packs I am determined to be able to cycle the TX
    pack too! It occured to me that if I use a tip-ring type 1/8" socket
    I will be able to wire it such that the battery is disconnected
    from the TX when I insert the 1/8" plug -- just in case I accidentally
    have the TX switched on...
    
    Jimi.

    I purchased an Ace cycler at the WRAM show this year and installed
    a TX and RX jack to it. I run also run JR radios. It didn't seem
    to work right and after trying it two or three times I got nothing.
    I then tries to change the TX on a std. JR changer and got no red
    LED. I'd seen the "no red LED" before so I checked the 3Amp fuse
    in the TX charging circuit and sure enough it was blown. I then
    gave the cycler to a sparky in my club and he told me that the JR
    runs a reverse polarity. On the Ace this means that the red lead
    from the cycler connects to the black lead of the JR charging
    jack. Once we did this and replaced the fuse everythings been great.
    
    
    Tom 

    ...or "Curiouser and Curiouser"...
    
    So I added the new 1/8" socket (3 connector normally closed type)
    such that with no plug in the battery is connected to the TX, and
    with the plug in the battery is disconnected from EVERYTHING except
    the socket/plug itself. I also carefully re-checked the polarity.
    
    The battery will charge, but STILL WILL NOT DISCHARGE. Pushing the
    button lights the red led only while the button is pushed. The battery
    voltage, however, measured at 10.4-ish, so it should cycle OK.
    
    I also wired up a connector lead for my Futaba 3 channel car radio.
    That one charges and discharges perfectly (600+maH indicated).
    
    I conclude therefore that there is something "wrong" with my JR
    battery. Either a cell  is dead or there is maybe a diode wired
    within the shrink wrap casing. I plan on finding out...
    
    Jimi.

    re .-1, me too Eric -- this pack is not fully charged, but at 10.4V
    should let the cycler discharge it.
    
    Anyway, I found the answer courtesy of Mr Taylors wonderful device.
    
    A bad cell. In fact 2 bad cells.
    
    I got real methodical (at last!). The no-load voltage of the battery
    when tested this evening was 10.26V. I attached a DVM and hit the
    test button getting a drop to 7.90V, thus the cycler (seeing less
    than 8.80V) said "not enough of them volt things" and refused to
    continue discharge. At this point I knew I had a bad pack and so
    cut it open so I could test each individual cell under load (as
    per Mr Taylor's instructions). Average no-load voltage was measured
    at 1.270V on each cell. Under test (load) 6 cells showed a drop
    to about 1.24V, but one dropped to 0.900V and one to 0.360V!!
    
    Nuff said -- new pack will be bought tomorrow. I plan on getting
    a Futaba pack with the PP9 style connectors (as I have in my car
    TX) and wiring up the appropriate Rat Shack connector to my charge
    socket inside the TX. This will let me swap packs about and make 
    any future replacement easier.
    
    This obviously ended up being another testimonial to the value of
    a good battery cycler...you can bet that mine will be getting heavy
    use from now on.
    
    Jimi.
    
    p.s. unfortunately, I am still mystified as to why "some JR's cycle
    and some don't", unless the above experience is in some way germane...

    On applying load to individual cells...
    
    Once I had removed the "shrink wrap" and the insulator end plates
    I was able to access the contacts for the 4 groups of 2 cells. I
    measured the no-load voltage on each group, then measured the load
    voltage by simply pressing/holding the test button. This localized
    the fault down to 2 of the 4 lots of 2-cell groups. I then carefully
    applied a new/sharp #11 blade between the insulation wrap of each
    2-cell group so the DVM probe could make contact with the connection
    between the in-line 2-cell group. Same procedure was then used for
    no-load & load tests on the individual cells, which ultimately found
    the 2 bad cells. I had cut the insulation carefully just in case
    I found that I could salvage/repair the pack; however I feel that
    I will trash this battery and buy a new one. As I'm sure all in
    this file will agree, the cost of a new TX pack is immaterial compared
    to the potential scenario of an out-of-control copter...
    
    Re .-1, Eric -- I too realized (via this experience) the need/value
    of applying a load to determine battery/cell condition. I had
    previously thought all was well, as the voltmeter on my TX showed
    a reasonable level of charge on the battery (insert a 1/8" plug
    into the C-VII's "direct connect TX to RX socket" and the meter reads
    battery volts as opposed to RF output level).
    
    One further question for you Taylor owners...
    
    Can I add some sockets to the cycler so as to plug-in a DVM to the
    TX and/or RX leads and use the DVM *without* hurting the
    calibration of the cycler? I ask because there is a warning
    in the cycler instructions not to add/remove too much to/from the
    lead lengths (changes resistance?). I suspect that a DVM has a high
    enough Ohms per Volt rating so as not to alter the lead resistance
    seen by the cycler. My intent is simply to be able to monitor the
    pack voltages during charge/discharge...
    
    Jimi.

re Note 126.104  "use [a] DVM *without* hurting the calibration"
    
    I believe so, but I have not actually verified it.  My belief is based
    on two items: you mentioned the light load, and the other reason is the
    imperfection in the calibration process.  The discharging portion of
    the Taylor is a resistive load with a concurrent clock.  Even if the
    resistor is precise, the calibration presumes a known and constant
    voltage --- neither is true.  The only thing of precision here is the
    clock rate, but the clock setting and reading are not at all precise. 
    
    I have modified my leads considerably, and I have often monitored
    the voltages and currents.

        re: a couple back
        
        I have built a bunch of "calibrated" packs of resistors to load
        nicad packs, and to cycle them before I got my Taylor. They are
        labeled for several different pack voltages and current drains. 

        All the answers are from Ohms Law. R=V/A; so for a TX pack 10v /
        .5a = 20ohms. W=V*A so the 20 ohm resistor should be 10 * .5 or at
        least 5 watt rating. I happened to have some big 40ohm resistors
        lying around. Two of these in series are about right for a TX
        pack, 4 of them for the RX. 
        
        Putting N resistors in series multiplies the resistance by N.
        Putting N resistors in parallel divides the resistance by N AND
        multiplies the wattage by N. Remember that these resistors will
        get VERY HOT when discharging batteries for any length of time.
        Burnt fingers can result, and if the resistor is not of sufficient
        wattage, fires can follow! 

        As to monitoring the charge/discharge voltage with a DMM, it
        shouldn't have much affect on the Taylor operation. I set up my
        cycler with Deans connectors, and then short adapters to go from
        the deans connectors to each connector type I use on various
        equipment. It would be easy to build a harness that is Deans to
        Deans, with a + and - tap for the DMM. 
        
        Similarly, if you want to monitor (dis)charge current, make a
        similar Deans to Deans cable, and cut the + wire. Use the ammeter
        as the bridge across this cut to monitor current. I haven't done
        this yet for the cycler, but have an aileron extension cable that
        I've used to measure servo load / no load current drain. CAUTION!
        make sure your ammeter can handle the range you are measuring.
        Many quit at 200ma, which is less than most (dis)charge levels.
        I've blown several DMM fuses by screwing up. Fortunately fuses are
        cheaper than DMMs. 

    A question on wiring the Taylor cycler to a Futaba radio:
    
    I have cabled the cycler for my Airtronics radio. It was a piece
    of cake and works quite well. I am going to wire up a set of cables
    for a friends Futaba, and I noticed that the Rx charger cord is
    3 wire! What goes on here? I will put a meter on it to find out
    whats going on on each wire, but could someone kindly explain why
    a 3 wire charge cable when, as I understand electricity, 2 are quite
    sufficient?
    
    Thanks,
    Randy

        Re:< Note 126.111 by PLATA::OSWALD >

        Randy,
        
                I used  a voltmeter to determine which of the three wires
        were + and  -  and then put a Deans connector on the two and left
        the third cut.   The Taylor cycler works like a charm on this.  I
        don't think the third wire has any function.
        
        Anker

    Yes, use a voltmeter.  However, if I remember correctly, there is
    "some" compatibility between airtronics and futaba.  I have used
    futaba charge cords to charge airtronics gear.  The fit is not what
    I would call trusted, but it did the job.  Maybe you don't have
    to change the connectors at all, or maybe futaba connectors will
    be sufficient for both of you.  
    
    DISCLAIMER: Like the instructions say, make sure that the polarity
    is correct, or you may damage the cycler.
    
    cheers,
    jeff
    

    Plugs aren't a problem, I spliced the Airtronics cords to the cycler
    with Dean's connectors so I could support multiple plug styles.
    I also put Deans connectors on the remnants of the Airtronics charger
    so that I can put the charge plugs back on it if necessary.

    I was just concerned about the Futaba three wire system, but now
    that I think about it I suspect that they just used a standard three
    wire servo cord and plug rather than tool up for the two wire plug.
    I'll put a meter on it and wire up the appropriate two wires. Thanks
    for the info.
    
    Randy

    The Red wire is +
    The Black wire is -
    The White wire is <NULL>

RE: < Note 126.117 by CSC32::M_ANTRY >

    Please read notes 126.9 and 126.14.

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Caster Oil!! "    
                      |_____/

     For all you LITCO fans I would like to have your expound on a couple
    of points that they mention in the adds:
    
    - Pulse operation with charge tapering to trickle after full charge
        Questions: Isn't Pulsed faster charging? or does it still take
                   12-14hrs?  Does it switch to trickle so that you can
                   leave it on indefinetly?
    
    - Fully protected against shorts and reversed polarity (unlike other
      units)
        Questions: Really?????? Doesn't the Talyor or Digipace do this?
    
    - Determines battery capacity or remaning flight time
        Questions: What does it spit out on the display and what does it
                   mean?
    
    - Why pay much more for a far lesser unit?
        Questions:  I dont know should I?
    
    Thanks.....I think I am just about ready!!!!

        re: 126.81 (still in catch-up mode) 
 
        The guy from S&R is right about storing nicads. The best way to
        store nicads is "fully discharged". If you don't know the
        condition of the pack, the only safe way to do this is as
        described, by discharging each cell. Discharging the whole pack
        could cause a weak cell to go into reversal, permanently
        destroying the pack. 
        
        I differ, however, in your definition of "full discharge". A nicad
        should NEVER be brought down to 0.00 volts. A cell is considered
        "fully discharged" when it reaches the knee of the discharge
        curve, around 1.0-1.1 volts. This is the point that most battery
        cyclers will take you down to. It may be the point where the
        flashlight bulb stops glowing; I'd need to try this with a DVM in
        the circuit to tell for sure. As any rate, do NOT leave the light
        bulb or other load connected for prolonged periods. 

        My recommendation for storing nicads (that are known to be in good
        shape; packs with no weak cell) for long periods (e.g. over the
        winter) would be to use your cycler to run them down, but not
        charge them back up until you are ready to use them. When the
        flying season starts, then get out your cycler, and charge them up
        and cycle them once or twice to be sure that they are still OK. 

        All of this information combines in my mind to tell me NOT to
        trickle charge nicads. This would seem to be the best source of
        the nicad memory problems that we're trying to prevent.
        
        Save the trickle charging for your gell cell. They like exactly
        the opposite treatment of the nicads. ALWAYS store them fully
        charged. Cycling is not necessary for their health; but can be
        used to measure their capacity. 

        Re: .94
        
        The resistor I was refering to IS the resistor (at least I assume
        that there is a resistor that does this) that sets the discharge
        threshold. I'm not sure if I'd have to change the discharge
        resistor to maintain calibration or not. 
        
        Anyone know how to make the change(s)???
        
        Re: somewhere else
        
        The white wire to the battery pack may be a vestigal feature. I
        remember a long time back that some battery packs were center
        tapped, so that in addition to the 4.8V you could also get +/-
        2.4V. I think some old recievers needed this configuration. The
        servos were 4-wire on these systems. My old Kraft gear had the 4
        wire cables and connectors, but as was mentioned the white wire
        was not connected. Charge them from the black & red wires only. 

>        condition of the pack, the only safe way to do this is as
>        described, by discharging each cell. Discharging the whole pack
>        could cause a weak cell to go into reversal, permanently
>        destroying the pack. 
>
>        I differ, however, in your definition of "full discharge". A nicad
>        should NEVER be brought down to 0.00 volts. A cell is considered
>        "fully discharged" when it reaches the knee of the discharge
>        curve, around 1.0-1.1 volts. This is the point that most battery

    Actually, a low rate discharge over a long period of time works quite
    well.  Vented NiCads can survive extended periods of reverse voltage
    without damage.  I use a C/10 discharge rate with a resistor to
    discharge my packs as a unit (these are 7.2 and 8.4 volt batteries for
    my electric planes).  Usually, I'll allow an overnight discharge, which
    often leaves the cells at or near 0 volts, followed by a high rate
    charge.  Cell charge acceptance is better at high charge rates (2C or
    greater) than it is at low charge rates (C/10) or less.
    
>        All of this information combines in my mind to tell me NOT to
>        trickle charge nicads. This would seem to be the best source of
>        the nicad memory problems that we're trying to prevent.


    NiCads develop memory as a function of their charge/discharge cycle.
    Lots of full charges after partial discharges will leave you with a pack
    that behaves as if it's capacity matched the average amount of discharge
    you give them.  Trickle charging does not contribute to NiCad memory.
    Trickle charging will not, however, erase a cell with memory.  The only,
    and best, way to do that is to deep cycle the cell a few times.
    Discharge it at a low rate and then recharge it at a low rate.

    NiCads can be left on a C/10 rate INDEFINATELY without damage, below
    C/50 they don't charge.  Technically you are overcharging the pack at
    C/10, but every modern cell is designed to survive this condition
    without damage. Higher charge rates cause the generation of heat and gas
    pressure within the cell (the two are related to each other, but not
    directly.  The cell can reach a stabilized temeperature under
    overcharge, and continue to increase internal pressure as a result of
    the production of Oxygen and Hydrogen) that can cause damage (cell
    venting, or damage to the internal structure of the cell).
    Interestingly, a NiCad will charge to a higher voltage level, and supply
    a greater capacity if charged at a rate over 2C.  Many electric car and
    plane enthusiasts are actually charging as high as 10C (with *VERY*
    accurate peak detection cutoff).  I've read of, but have yet to see for
    my self, that typical 1200MAH packs supply as much as 25% greater
    capacity if charged at these high rates.  The key is the detection of
    the completion of the charge.  You can charge any cell at almost any
    rate you'de like, so long as you stop it when the cell is up to
    capacity. 
    

    It seems that there are different recommendations on charging depending
    on the use of the the batteries. I'm confused about which are valid for
    which use. 

    We have two drastically different ways in which we use NiCads in R/C: As
    power for radio transmitters/receivers, and as power for drive motors.
    The requirements are quite different.

    Radio batteries typically drain at low rates, (C/2 or less is typical).
    The requirement for these batteries is to supply reliable power for the
    rated capacity (measured in hours), and the results of a failure could
    be catastrophic (crashed plane or worse). 

    Motor power batteries typically drain at a very high rate (10C or more)
    and the goal is to get the most juice you can for as long as you can
    (measured in minutes or seconds). The results of failure is usually not
    catastrophic (shorter flight). 

    When I see advice given about the care and handling of NiCads it's
    sometimes not clear which category of operation is implied behind the
    advice. It's possible that the cell design is different for different
    types of usage. I would be much more wary of damaging radio batteries
    than power batteries. What are the major differences in battery handling
    between these two types of use? 

    Dave 

        I'd be curious as to your reference material. Anyone have a good
        reference on nicads. Everything I've ever read says that total
        discharge to 0.00V can be harmful to the nicad cell. I've
        certainly trashed plenty of cells that way. Even the tricks to fix
        them only work for a short time, and then it's time to replace the
        cell. 
        
        I have heard that the very high charge rates can pack more charge
        into a cell. It almost seems like cheating for racing and the
        like. 

One of the great things about wrecking planes in one or two
flights is that you get to learn neat things about the care and
feeding of nicads.

My charger has three rates, C/10 or 50 mA, C/25 or 20 mA, and
C/100 or 5 mA.  I can also test the batteries under a 250 mA
simulated load, or I can cycle them down to the 1.1 V/cell level
at the same rate.  This is all you need to maintain radio
batteries.

I use the C/10 rate only after fully cycling the batteries, which
I do every 8 weeks or so.  Or if the batteries have been
discharged for some accidental reason, like leaving them plugged
into the charger with the charger turned off, a recent "gotcha".

My normal routine is to check the batteries early in the week
with the test button.  If the batteries have fallen to their
rated charge level, 4.8 or 9.6, I give them a 20 mA charge.  If
the batteries are still above that level, as they will be for the
first 15 or so minutes of operation after a full charge they get
the 5 mA charge.

Now, the reason for all this elaborate detail is to show that
both the 20 mA AND 5 mA rates are effective.  If the battery is
nearly fully charged, that is above its rated voltage, a 5 mA
charge overnight will bring it to the fully charged condiditon;
the voltage in the cell does go up to 1.31 nominal volts.  The
same holds for the 20 mA rate.

I know that conventional wisdom says I'm asking for memory
problems, but I have not seen them.  I've read that the cells
manufactured in the last 5 years or so (and you are asking for
trouble by using older cells for your radio) have no significant
memory problem, and I believe this. The trick is in regular
cycling. 

As a side note, I run the batteries in my walkman radio down flat
at least once a week and recharge them.  I've been doing this
steadily for the last 3 years, and they are disgustedly healthy.
I've also stored packs in fully charged and discharged
conditions, though I prefer to store fully charged and to
recharge them at C/10 once in a while (when I think of it) with
no bad effects.  When stored fully discharged I have to cycle the
pack 2 or so times to get it really solid, but I've not seen any
real loss in performance. 

    
    	I listen to all this info on different charge rates, but I have
    a Taylor cycler and all I do is after a few hours of actual flying
    time I cycle the packs.  Is this okay?  I figured cycling was better
    than guessing at the charge rate and hooking up to the charger for
    15 hours.  I don't have any measuring equipment.
    
    Ken

    There are two types of NiCad Cells.  Sealed and Vented.  Both provide
    the same function, but have differing charge/discharge characteristics.
    Almost all NiCads in radio gear, like the Cells used for motor power,
    are vented cells.  Vented cells can withstand significant overcharge,
    and high duty cycle use, much better than sealed cells.  Sealed  cells
    relly only get used nowadays for applications where the environment
    prohibits the use of vented cells (Very high pressure, or low pressure.
    sealed environments where the venting of explosive gases would be
    dangerous).  Regardless of the capacity of the cell, if it's vented, you
    can treat it the same as for any other capacity.  Smaller cells actually
    survive mistreatment better than larger capacity cells, since they
    typically have a larger ratio of surface area to cell capacity, and that
    determines how much heat the cell will generate, and how well it will
    dissipate.

    The only reason you don't see a lot of fast charging of radio batteries
    is that, usually, there's no need to do so, you get as much flying from
    a single overnight charge as you want (there are Fast Field Chargers for
    radio batteries, though, they can be fast charged quite successfully at
    high rates).  The "Fast-Charge" cells that get sold for motor power
    differ from slower rate cells only in their ability to deal with an
    overcharge condition.  Fast charge cells withstand the stresses better
    than slow charge cells.  The key here is that if you can accurately
    detect the end of the charge cycle, and remove the cell from the high
    charge rate BEFORE it's in overcharge, you can fast charge ANY NiCad.

    The batteries that I use for my motor systems get a deep cycle everytime
    they run.  After a flight is over, I'll let the motor run until the
    batteries barely have enough juice to turn the prop, then I'll let the
    pack cool off for a few minutes and recharge it at 4C.  They handle this
    kind of usage cycle quite well.  I've yet to notice any degradation.
    Electrics can't really fly if the power system isn't up to snuff.  I've
    had a few packs (cheap ones, bought at discount) that couldn't fly my
    planes at all.  The packs that do fly the planes have been doing so for
    two seasons now without any noticable loss.

    Quoting from the GE NiCad Applications guide :

         Single  cell  batteries can be completely discharged at will. 
         To the extent feasible, it is recommended that steps be taken
         to  limit  the  frequency of very deep discharge in multicell
         batteries  using  SEALED  CELLS.   Because  of   the   slight
         differences in capacity between cells, one or more cells will
         run out of charge  capacity  before  the  other  cells  in  a
         multicell   battery  reach  zero  voltage,  causeing  reverse
         charging of the lowest capacity cells.

         ...

         Vented cells can  tolerate  significant  periods  of  reverse
         potential    without    damage   or   permanent   performance
         degradation.

    My experience agrees with Randy's.  It is ok do FULLY discharge a cell
    but don't do it to a pack unless you know it's balanced.  Reversal does
    damage a cell and that will happen if one cell fully discharges before
    the others.  That's why all literature says to stop discharge at 1.1
    volts per cell to prevent the weaker ones from going into reversal.
    I have gone into packs and discharged individual cells to zero by
    connecting a resistor to each cell and leaving it on for an hour.
    
    Charlie
    

    Does anyone have any information on the life of a nicad as a function
    of age as well as the number of charge/discharge cycles? For what
    it's worth, I have a Philips razor which is powered by a pair of
    C sized nicads. My procedure is to use the razor until the red light
    tells me to recharge, and then charge for 24 hours. I would assume
    that this mehtod approaches the ideal cycling technique for maximum
    life. I bought the razor almost exactly four years ago and the battery
    capacity has just started to drop dramatically; from about 21 days'
    use to about 6. According to my calculations, I have put the batteries
    through about 70 cycles. This does not compare favourably with my
    belief that nicads should cope with 500 to 1000 cycles before
    degrading!
    
    My Tx is just on three years old: maybe it's time to start checking
    the capacity very, very carefully!
    
    Comments?
    
    Tony
    

It looks like you're treating those razor nicads ok.  I'd think
that maybe the type of use, that is running a small motor at
lets say 1 amp, has something to do with it.

Tx batteries run at about 180 mA, so there's quite a difference
here.  The difference is that the razor batteries generate
significant heat at their discharge rate, whereas the Tx
batteries don't. 

However, I think that in general a good rule is to chuck a set of
batteries after 4 years or so...

I have three sets of AAA nicads that I use on my "boogie radio"
at work.    These batteries gave about 10-12 hours on the radio
when new.  Friday I had an all-night radio session and ran them
down in about 5 hours -- went through two sets!  Its my practice
to run the batteries until they're flat and then recharge.  I've
been doing this for about 4 years now.  These batteries are ready
for the graveyard; since the use is not critical, I'll take my
time replacing them.  

I think that the only way to measure a battery's capacity, or
rather condition, it to to a timed cycle.  Put the battery on a
Standard Load of C/2, or 250 mA in the case of our radio
batteries, and time the discharge.  Let me emphasize the standard
load: any other test condition is pure bunk.

If you were a real Boy Scout, you 'd have done this when the
batteries were new, and you would have plotted a discharge curve
for them.   Then you could check the batteries periodically
against this curve for condidition. 

But of  course, we're all sloths, not scouts, so we just say that
if we get 1 1/2 to 2 hours on the test the battery has not
depreciated significantly.  I would consider 1 to 1.25 hours a
flunking score.

    I'll look at it, Jeff.  I have to fix mine anyway.
    
    My Taylor has had an electrical, not mechanical, failure.  It is
    probably my fault for misusing it, but I'll describe it here in case
    the symptoms are not unique to mine.  The problem is in the TX side. 
    
    The other day I finished repairing the Kadet and put my radio on the
    Taylor to cycle.  The receiver side cycled OK, showing a residual
    charge of 500 mAh on a 600 pack.  The transmitter stopped discharging
    at 360 mAh with a blown fuse.  This happened during the night, so I
    don't know if the fuse went at the time of switch-over or before/after
    that time.  I suspect the switch-over sequence might have a problem.

        My Taylor cycler broke this weekend. I was cycling a 6v (5 cell)
        AA pack on the RX side (calibrated for a 4.8v pack, but I've been
        doing this for as long as I've had the beast; I'm only concerned
        with a change in capacity, not the actual number), and it stopped
        at about 100mah. After verifying that the pack was fully charged,
        I tried again. Immediately after pushing the red button, the
        cycler dropped off discharge and started charging. I've since
        tried it with several packs, from 4.8v to 10v, and all drop off
        the discharge cycle immediately.
        
        The TX side seems to be working fine. I opened up the unit, and
        saw no visible evidence of fried components. Anyone got an idea on
        what might be wrong? Therre are no fuses or any obvious things to
        check inside the box. Is it a DIY fix? If not, anyone got an
        address and phone # for Taylor (or a pointer to the right note).
        Are schematics available?

        I'd welcome a copy of the (either/both) schematics. My mailstop is
        ACI.
        
        I found the note with Taylor's address and phone number. They have
        since moved down the street, and changed phone numbers. The new
        information is:
        
        	L.R. Taylor
        	22122 Roscoe Blvd
        	Canogha Park, CA 91304
        	818-704-8950
        
        The gentleman I spoke to there said that my problem is probably
        the Red LED that died. He said that it needs to be recalibrated
        after a LED replacement, as the LED is part of the measuring
        circuit. Perhaps this weekend, I'll take a stab at it myself. If
        all else fails, I'll send it back to them. He said that repairs
        would probably be $22, including return postage, and take a week.
        Jeff, does that match with your experiences?

    I can send you a copy of my schematic, but if it really is the LED, you
    probably don't need the schematic. After replacing the LED, use an 
    adjustable power supply to place a voltage on the battery test
    terminals. As you lower the power supply voltage, the circuit should
    transition from discharge to charge at 4.4V for the receiver, 8.8V for
    the transmitter. There are two 100 ohm pots used to calibrate the
    transition voltage, one each for the two circuits. Near as I can tell,
    that's all you need to do.
    
    Mind you, I think it's a pretty lousy design.  It relies on using the
    diode and the base-emitter junction of a transistor as a "reference",
    and that not only varies from device to device, it varies quite a bit
    with temperature. That's why they suggest you wait for the box to cool
    down before testing another battery. On the other hand, the results are
    pretty consistent, and there's no doubt it's cheap to manufacture.
    
    Dave
    

    I have a copy of the official [four page] prints together with
    annotations that I made when I worked on the circuit a couple of years
    ago.  (Reality did not agree with the prints.)  Send me mail via 
    >Notes  SEND/AUTHOR with your mailstop, and I'll send out copies.
    I'll first send a copy to Dave Walter for his comments.

    I abused mine by using it to charge whatever batteries needed service. 
    Like Dave, I was not impressed by the circuit; someday I'll replace
    the guts with a decent circuit.  Until then it mostly gathers dust.

    Alton
    

    Led's have TERRIBLE voltage vs temperature characteristics.  A circuit
    like Dave described is just plain awful.  I'm glad I built my own.  I
    was disappointed when I had a 2% drift in my reference as my circuits
    warmed up. :-)  I used a plain old zener diode for a reference but I
    just bought a temperature compensated reference diode to upgrade it.  I
    use an old PC for the data collection and display so there is an A/D
    converter in my cycler that also needs a 10V reference.   
    	By the way, I have schematics for the DIGIPACE cycler and it is a
    good design.  It is not as flexible as mine because the stop voltage is
    not programmable.  Mine will work with from 1 to eight cells and
    discharge from 10ma to 10 amps!  I can cycle the packs for my electrics
    at high currents.  The measured capacity of Nicads varies greatly with
    the discharge rate.  I think that most cells are measured at C/2 when
    they are rated.  I usually only get about 80% capacity if I discharge
    at the C rate.  (which I usually do to save time)
    
    Charlie
    

    Ok, Charlie. Where/when can we get a schematic, parts list, and PC
    board mask? I'd love to do better than my RAM simple cycler. One feature
    that I'd like to see would be an interface to a clock chip so that it
    stores/displays the discharge time for unattended operation (without
    loss of the discharge info. I want to build several of these since 
    cycling everything one at a time is getting to be a pain.

    Jim, Litco Systems makes a nice LCD unit that I have.  See note
    126.9 for more details.

                                - Dan Miner

	Getting back to the original broken Power Pacer... I have schematics
	available in postscript format. You can copy them from:

		PWRVAX::STEALTH:[WALTER.PUBLIC]POWER_PACER_1.PS
		PWRVAX::STEALTH:[WALTER.PUBLIC]POWER_PACER_2.PS

	Page 1 is the receiver circuit, page 2 the transmitter circuit.

	I don't know how these compare to the "published" prints; I just
	sketched it out from the circuit board.

	Dave

Since a gaggle of us did a group purchase of these L.R. Taylor units
and since they seem to work fine although slightly limited.  Perhaps
Charley you wouldn't mind taking a look at the schematic and coming
up with some simple upgrade mods.

For instance - I was at one time real interested in ordering the ACE
auto trickle unit for their Digipace - hoping that somehow it could
be connected to the L.R. Taylor.  I gave up - but I sure wish I could
kick over to trickle after a full charge has been attained.

Now ACE has a new Digipace II that looks interesting.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

>>  L.R. Taylor ..... simple upgrade mods.

    I have the same interest --- and will probably never get around to
    designing what I'd like.

    Many of us with a Taylor do not have a PC, let alone an interface.  
    But the Taylor mechanics include a pair of timers [with old fashioned
    displays that work].  I wouldn't mind turning a multi-position switch 
    to input the number of cells, another to select the discharge rate, and
    a third to select the charge rate.

    I'll look at the schematics but I probably won't have time to do much
    with it until after the flying season. :-)  I have most of the design
    done on a very nice cycler/charger that will do from 1 to 8 cells both
    fast charge and cycle discharge.  It will be able to work at the field
    off of a 12V car battery and it will download cycle data to a PC via
    RS232.  I have lost interest in electrics so I've been slow to finish
    this.  Bill Lewis, the co-designer has also been too busy to work on
    it.  I really did want to get it done this spring, though.  My old PC
    version works fine but it ain't too portable and it ties up the PC
    during the cycling.  I don't have schematics on line but I'll try to
    bring them to the next DECRCM meeting if I can make it myself.
    
    Charlie
    

        Whomever I spoke to at Taylor was quite correct; I replaced the
        red LED this weekend (it's orange now, but so what), and the unit
        now works fine. 
        
        Couldn't I calibrate it if necessary just by monitoring the
        battery voltage as it switches over from discharge to charge, and
        see where it cuts out. I tried this on the TX side before fixing
        the RX side. I was building something with an 8 cell pack
        permanently installed and hard wired. I felt safer working with a
        discharged pack, so I connected it up, but did not plug the cycler
        into the AC. Pressing the test button discharged the pack, but
        gave no readout on MaH. 
        
        The pack will recover a bit, but now you have a quick test
        available. I connected up my DMM leads, and pressed test again.
        Very quickly the pack dropped from about 9.2v down to 8.4v when
        the discharge cycle stopped. After waiting a few minutes, I tried
        again, and again the voltage dropped from 9.2 to 8.4, this time
        even faster.
        
        This leads me to believe that my unit might be slightly off
        calibration, but only by about 5% or so, which is close enough for
        my needs. Unless someone can suggest a better way, I'll use this
        to test and recalibrate if necessary the RX side.
        
        I did make another discovery inside the cycler. The only thing
        that holds the circuit board in place inside the unit is the
        tension on the two wires that you connect up to your battery
        packs! I didn't think much of this, so after I fixed the board, I
        used a few dabs of hot melt glue to hold the board in place, and
        released the stress on the two test wires.

    According to page 4 of the March 1992 RCM, Taylor has moved again.
    
        L.R. Taylor & Co.	818/997-6845
        15624 Vanowen Street
        Van Nuys, CA  91406