Leaking NiCd??

[Negeltu]

I have a NiCad Battery that overheated in it's charger one morning because the power cut off and came back on a few times while I was sleeping. It has some residue around the edge of the button on the positive end. I tested it's current and voltage against good NiCad batts of the same lot....and it reads just fine. Is it ok to continue using this battery or should I send it to be recycled?

 

[JSWrightOC]

If you see residue (white crystals or a clearish liquid) then I would recycle the cell, even if it tests normal. While it may continue to function now, its life has been compromised now that some electrolyte is lost. Invariably the chemical balance has been thrown off as well, and this is what leads to cell failure. Since it got hot enough to vent, it may also be hazardous when fully charged--if the plates inside short, you'll have a "hot steamer" which can be a dangerous situation indeed. This would be a plausible scenereo if the separator fails or has been damaged to the point of allowing the plates to touch. I would discharge it to near-dead capacity as safely as possible and with little mechanical disturbance, and then recycle it at your convenience. If the electrolyte gets on you (potassium hydroxide), wash it off with soap and water.

 

[Negeltu]

It is not white or clear. It is actually more brownish? /ubbthreads/images/graemlins/smile.gif I think I will just take it in to recycle it... thanks for the input.

 

[JSWrightOC]

Brownish? Hmmm. Yeah, that's probably your safest bet. Either way, it's not going to perform to specifications before too long. The shorting out hazard is actually pretty remote, but the hazard exists nonetheless--just didn't want you to have any suprises. /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/grin.gif

Sorry that it happened!

 

[batterystation]

If you continue to use it, it will just eat anything that the electrolyte gets on anyway even if the cell does work for a while. I agree with above. Replace it.

 

[Negeltu]

Thanks guys. I just replaced them with some 2200mAh NiMH's. The power here in this part of Oregon gets pretty unreliable in the winter. The slightest bit of wind can sometimes cause a brief outtage. I have to strategically time when I recharge my batteries in the winter...lol. The charger that I use is a Maxell AA battery charger. It charges NiMH's and NiCad's. It says on the package that it senses the charge of each individual battery and cuts off when fully charged. I don't know why it goes back into a full charge cycle if the power is interrupted... /ubbthreads/images/graemlins/frown.gif I can't afford the more expensive battery chargers. This one was $22. It came with 4 NiMH's.

 

[Wingerr]

I charged my brand new Nexcell 2100's for the first time with my Maha 777 Plus in a 6 cell configuration, and another set with my Maha C204, and three of the cells vented- It caught my attention on the 777 when I heard a hissing sound.
I took them off the charger, and saw the telltale residue on two of the cells. There was no unusual cycling of the charger, and the charge input was below the 2100mAH level, though they could very well have attained full charge. Could be the delta-V on these batteries are smaller than usual, and failed to trip the charger cutoff.
Thought it might have been a fluke, but a second new set I put in terminated charge with the ERR3 indication, which is from the temperature sensor limit. Went to the C204 with another set.
Checking the batteries coming off the C204, which went through a normal full charge cycle, one of the four cells ALSO showed evidence of venting, to my dismay. (!)
I wonder if these cells are better suited to slow charging rates... I'm certainly going to be leery about using them in quick chargers unless I keep close tabs on them while they're charging.

 

[UK Owl]

Only use a 'fast' charge if the cell is rated for it or they can vent electrolyte as you have seen!

Once you lose electrolyte you have lost some capacity, if only one cell in a pack this cell will 'run out' first and will then be destroyed by a reverse charge put into it.

Best bet - recycle the cell, and notch it up as a lesson learned.

p.s. a battery in this state will still show a full charge voltage of approx 1.35 volts, and will still be able to supply the same levels of current as an undamaged cell, it will simply run out quicker.

Also be aware that the manufacture of NiCd cells means that a couple of charge / discharge cycles as part of the manufacture. Some manufacturers do not perform this step, but some do. If they do they often ship the cells part charged, so if you use a 'dumb' charger you can easily vent the cells on their first charge, if you have a -Delta V charger this should not be a problem.

 

[Negeltu]

Yeah, my problem was definitely from the power cutting on and off. My charger takes 9 hours to charge my batteries. It's not one of those quick chargers.