Need to recover NiCad Pack

[jrmcferren]

My new hobby of amateur radio (call: KB3PXR) has been keeping me off CPF. :thumbsdow I have borrowed a handheld transceiver (Walkie Talkie) off of a friend and the battery pack took a turn for the worse. This friend knows about the troubled pack as I borrowed the alkaline battery case off of him to stay on the air. The battery indicator is indicating low battery on a fully charged pack, a discharge test with a resistor bank (and the radio on receive to indicate cut off) determined that the battery pack is carrying a full charge. Self discharge is very high (about as bad as energizer 2500s).

Even though I am under no obligation to restore the pack, I would like to do so anyway. The most important reason is alkalines do not like the drain of the radio at full power. Think of this as running a 6D ROP on alkalines, as when the cells are dead in the radio, they can still power consumer level (Mag) flashlights at a decent level.

Charge/discharge cycles are hard because my school is breaking their own rules allowing me to have the radio in my possession (ask in PM if you really need to) and I definately cannot use the radio like I do here at home (good thing because the pack takes 20 hours to charge). This does not mean I am unwilling to do said charge/discharge cycles, I just have to make sure school officials don't see it.

The charge is the radio's built in charger and the discharge is the radio powered on with the battery pack connected to a 20 ohm series/parallel battery bank.

Since this is borrowed, I cannot disassemble the pack.

Battery pack details:

Rechargeable:
Model: ICOM BP-196
Volts: 9.6
Capacity: 1050 mAh
Made in Japan

AA case:
Model: Icom BP-194
Volts: 12 with Alkalines, 9.6 rechargeable
Capacity: Depends on installed cells
Minimum cells: 8
Maximum cells: 8
With NiCad cells installed functions as a bp-195 or bp-196 depending on cell capacity except no desktop charge capability.
Made in Japan


73
John McFerren KB3PXR

 

[TinderBox (UK)]

Hi.

what voltage are you getting on a fully charged pack, wait 30mins after charging before reading voltage.

Their are most likely dead cells in the pack, the voltage will give us an indication of how many.

regards

John.

 

[jrmcferren]

Ok, I didn't have a DMM at my location, I'm going to get one out of my shed now. I think it is a voltage depression issue. Too bad it is not my buddy's Yaseu as it displays the battery voltage at turn on.

 

[jrmcferren]

After a full charge, I have determined that there are multiple failed cells in the pack. Thank you for your help the final voltage was 8.5.

 

[hopkins]

Do a web search for Nicd battery pack repair or fix.
I've brought back to life some dead cells in the nicd pack for
a BlacknDecker portable drill I was given

It was sort of fun. Got to open the Nicd battery pack and expose the
individual cells. Leave the spot welded cell-to-cell connection straps alone!
2.Just identify the dead cells with your volt meter and mark the +/- sides with a marker if they are not. Mine were unmarked, C-cell sized industrial grade and looked almost the same cathode and anode. So figure out and mark the +/- sides.

3. now the fun part: bringing them back to life. Got to momentarily charge
JUST THESE DEAD CELLs (not the whole pack!) with several amps of current.
12volt lead acid car battery is perfect. I used aligator clip leads hooked to my
car battery and connected (ie briefly touched them to just the dead cells)
expect a small spark:twothumbs.
1 or 2 seconds only.Do not reverse charge.
4. measure the cell. If its now at 1.2volts you're done, if not zap it again. Then go to the next dead cell and give it the zap.
5. then reassemble the pack and charge it up normally. Is it back to full
voltage? If not repeat step 3.

 

[twosouls2gether]

Do a web search for Nicd battery pack repair or fix.
I've brought back to life some dead cells in the nicd pack for
a BlacknDecker portable drill I was given

It was sort of fun. Got to open the Nicd battery pack and expose the
individual cells. Leave the spot welded cell-to-cell connection straps alone!
2.Just identify the dead cells with your volt meter and mark the +/- sides with a marker if they are not. Mine were unmarked, C-cell sized industrial grade and looked almost the same cathode and anode. So figure out and mark the +/- sides.

3. now the fun part: bringing them back to life. Got to momentarily charge
JUST THESE DEAD CELLs (not the whole pack!) with several amps of current.
12volt lead acid car battery is perfect. I used aligator clip leads hooked to my
car battery and connected (ie briefly touched them to just the dead cells)
expect a small spark:twothumbs.
1 or 2 seconds only.Do not reverse charge.
4. measure the cell. If its now at 1.2volts you're done, if not zap it again. Then go to the next dead cell and give it the zap.
5. then reassemble the pack and charge it up normally. Is it back to full
voltage? If not repeat step 3.

Ahem to that, I've done the same thing to a few drill packs. Although from what I've heard (read actually) those dendrites have already poked holes in the seperator, making it easier for them to grow back again. Then again, it's pretty free, don't need to spend money on a new pack and should last a while longer. :shrug: I would see if you can open the pack with screws or something. Maybe it snaps together?

 

[VidPro]

what hopkins did was get them off of 0V, once you do that, the slow charger will charge them again. it wont nessisarily fix the weak dead cells, but untill they get off the floor, they wont be doing anything at all, in fact a slow charger will end up charging worse with cells STUCK at 0V. so giving them an "ammonia Inhalant" never helped the patient , but it sure does wake them up

--1.2---0v---1.2---1.2---1.2--

--1.4---0v---1.4---1.4---1.4--

 

[hopkins]

I did'nt want to spoil to fun by saying its not permanent. I eventually got a
new drill w/batt packs but kept the old ones as a science demo.
People seem to be always ready for Frankenstein science of bringing the dead back to life.