| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1522.1 | Similar problem | MISFIT::BLUM | | Tue May 18 1993 12:50 | 14 |
| Kay,
A very similar thing happened to me 2 weeks ago. I was using a
JR switch harness with a futaba 250mah battery. My problem was
the battery would not reliably charge through the switch harness.
The light would come on the charger, but when I test cycled it on
my L.?. Taylor cylder it would switch to charge mode within a minute.
Changing the switch harness seemed to fix the problem.
Regards,
Jim
|
| 1522.2 | SWAG | CSTEAM::HENDERSON | Competition is Fun: Dtn 297-6180, MRO4 | Tue May 18 1993 13:05 | 1 |
| My money is on Black-wire...........
|
| 1522.3 | Just Curious | ANGLIN::BEATTY | | Tue May 18 1993 14:14 | 10 |
| I'm just curious, at what rate are you charging this 110MAH Battery???
I am convinced I ruined three 250 MAH batteries by using the 50MAH
rate for too long a period of time, i.e. 12 hours. Assuming I had a
shorted cell I took them apart, but no shorted cells, just seriously
reduced capacity. Probably vented them.
Will
|
| 1522.4 | Been there. | CSTEAM::HENDERSON | Competition is Fun: Dtn 297-6180, MRO4 | Tue May 18 1993 14:26 | 5 |
| The tell tale sign of white powder will confirm that you vented them. I
killed a couple that way by charging overnight when they were already
charged right up.
E.
|
| 1522.5 | venting questions? | MISFIT::BLUM | | Tue May 18 1993 15:04 | 14 |
| re: venting of nicads
I thought nicads vented when they got too hot.
A seal melts to allow the discharge of gas, preventing the cell from
exploding.
I question whether 50mah of current could heat a cell enough to
allow venting to occur.
Regards,
Jim
|
| 1522.6 | For what it's worth. | CSTEAM::HENDERSON | Competition is Fun: Dtn 297-6180, MRO4 | Tue May 18 1993 16:15 | 10 |
| All I know is that every nicad that ever had that lost its performance
had a certain amount of white powder around the vent holes.
Overcharging has always been the culprit to date.
On timed charges and cycled packs I have never reproduced the white
powder in the last 4 years. (Sample of 15 Rx packs monitored).
Regards,
Eric.
|
| 1522.7 | Possible Solution | LEDS::WATT | | Tue May 18 1993 20:41 | 15 |
| The vents are spring loaded on most nicads so that they can reseal.
You could vent 250 or less mah cells with a 50mA charger.
Kay, Without doing some measurements, I can't tell what was wrong
but it sounds like you had some extra resistance in the circuit that
prevented the other chargers from reaching the current required to
light the LED. You might have been getting some current but not enough
to turn on the light. It really does sound like a connector problem.
Are sure you hooked the harness up right? There are two ways you can
hook up most harnesses - and one is wrong. The end of the switch with
one wire should go to the receiver. The other end has a male and a
female plug. One goes to the Nicad and the other goes to the charger.
I have hooked the harness up backwards and had charging problems.
Charlie
|
| 1522.8 | One bad cell | KAY::FISHER | The higher, the fewer | Wed May 19 1993 20:42 | 47 |
| Well - last night after setting on the L.R. Tayler the night before
I cycled it.
It cycled from discharge to charge in about 2 seconds.
I removed the pack and measured with a meter - about 5.8 volts.
I put a expanded scale voltmeter on it next and it started out in
the green but in about 5 seconds dropped to the red.
I measured the voltage across every cell and they all measured 1.2 volts
except for one cell which would only flash the readout on my meter?
So I took the pack apart and removed that cell. It also must have gotten
hot cause it had split the fancy insulation. I brought it in today
and it is right in front of me - no power around the vent holes.
Now I have to call Mr. NiCad (E.H. Yost) and mail order another.
I tried Toms Hobbies and they don't have that size in stock.
I fiddled with the cell quite a bit. On the one hand it acts open
in that it wouldn't light the charger light (originally) and on
the other hand it acts shorted when you look at the output voltage
on a expanded scale voltmeter. And the total reading equals the
reading of the other 3 cells.
About overcharging - I have been a bit ruff on it but my feeling
was the standard chargers are constant voltage so they should
decrease their charge current to trickle levels as the pack becomes
fully charged and the voltage increases. Right Charley?
Of course with a cell shorted out that increases the current and keeps
it there! I had that happen on my electric drill - twice. A cell would
short and the darn thing would get really hot charging up.
I'll be searching thru the notes file for the phone number of E.H. Yost
so if anybody has it handy please send me mail - I'd like to call
yet today so maybe I could have it ready in time for the HLG contest
this Saturday in Minot Maine.
Bye --+--
Kay R. Fisher |
---------------O---------------
################################################################################
|
| 1522.9 | No Cigar | LEDS::WATT | | Thu May 20 1993 16:45 | 14 |
| Wrong, Kay. Nicad chargers are mostly constant current or nearly so.
It's true that the standard chargers are unregulated, but they have a
large series resistor so the current does not change that much with
battery voltage. It sounds like your cell is basicaly an open circuit.
Some internal failure must have destroyed it because the usual failure
mode is a short. With a shorted cell, your charger LED would have
always come on but the cycler would have tripped almost immediately.
An open cell can read zero volts but a digital meter will usually flash
and hunt around. An internal low resistance short could have caused
the cell to self destruct. It probably had nothing to do with
overcharging. It was very likely a manufacturing defect.
Charlie
|