Best way to activate unused NiCD batteries

I have some old AA NiCD batteries. They are not used for many years. I tried to charge them on c9000. The capacity reached 3xxxmAH (battery capacity is 1100mAH) while the charger still did not stop charging. Then I manually stopped and started discharging. Capacity was only about 900mAH.
Then I tried charging them on another BT-c2000 charger. This time the problem was charger frequently stopped charging after the capacity reached 5xx mAH.

Why one charger couldn't stop while the other frequently stopped far before full charge?
And what is the efficient way to restore or activate a NiCD battery? Should I just cycle them several times (manually stop charging every time)? Should I discharge then short circuit them till 0V before charging?

Hello Tbx8192,

Welcome to CPF.

Try using the Break In function on the C9000.

Tom

I had some 5000mah C night battery's sitting barley used for 8 years or so., I did a capacity test and only got around 300mah , after a few discharge/charge cycles I got them to around 3000mah, and I hope to recover at least 4000mah.

John

SilverFox said:

Hello Tbx8192,

Welcome to CPF.

Try using the Break In function on the C9000.

Tom

Click to expand...

Thanks.
I already tried break in, got 800-900mAH. Then even if discharged at 100mA, I still couldn't dump the remaining 200mAH. I also tried to break in again. Capacity did increase but the progress was rather slow. Then I tried cycling 3 loops (200mA charge, 100mA discharge. Charge stopped at about 13xxmAH), result was capacity did not increase at all (almost same each time)

SubLGT said:

http://batteryuniversity.com/learn/article/how_to_restore_nickel_based_batteries

Click to expand...

Thanks. This is what I need.
So deep discharge using short circuit is one way to decompress the internal large crystals. I will test it later.

Does freezing nihm cells restore any capacity, as there are a few guides that say to free cells for 17hrs in an ziplock bag, but do the checmicals in an nimh battery even freeze in an domestic freezer.

Is this (Snake Oil) ???

John.

I remember having AA NiCD cells. I think a capacity of 800-900mAh (measured during discharge) is actually about right? I seem to remember the highest capacity NiCD AAs I had were around 900mAh or so. What capacity are yours rated for?

zipplet said:

I remember having AA NiCD cells. I think a capacity of 800-900mAh (measured during discharge) is actually about right? I seem to remember the highest capacity NiCD AAs I had were around 900mAh or so. What capacity are yours rated for?

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Battery type is Sanyo's KR-1100AAU. Rated capacity is 1100mAH. It is assumed largest capacity AA NiCD cell.
Now two cells are broken in on c9000. Discharge capacity is around 900 (in previous break in).

tbx8192 said:

Thanks. This is what I need.
So deep discharge using short circuit is one way to decompress the internal large crystals. I will test it later.

Click to expand...

i used "zap" circuit from disposible cam to zap each cell in an amost dead pack, it did work for a little while, not a solution to fix them permanently, but rather prolong their life a bit. i also read about using car battery charger to get like 10A going thru them allegedly it would brake up crystals too, but never actually tried it.