Ni-Cd care

[Kez]

I bought two 6-cell "Sport packs" last year that are rated 2000mAhr. When I cycled the packs the capacity was actually between 2200 to 2400mAhr. The packs were used in a cabin crusier powered by a Magnetic Mayhem and I guess the max current was no more than 20A. I charged the packs at 2.5A.

Both packs saw no more than 15 runs each and at the end of last season, I discharged them to 1.1V/cell before putting them away.

When I charged them for the first time this year yesterday, I am disappointed to find that the capacity has dropped to 1200mAhr! Cycling the packs has not improved the capacity much. Have I done anything wrong or is it the quality of the "sport packs"? I am not sure what kind of cell they used in the packs but I think it is safe to assume not Sanyo.

Thanks for your input.

Kez

 

[jstevens]

Hey Kez,

It has been my experience that Nicads don't like to be stored charged. Assuming that your sport packs are in stick configuration (pos to neg, end to end) there is not much you can do except leave them with a little charge. I usually take mine down to .9v a cell, 1.1v seems a little high. Usually after a while the cells crystalize if they have a charge in them and go bad after months of sitting around with no action done to them. Another thing that happens is they fall out of match with each other. Usually the cells decay (lose voltage at different levels) sometimes never recovering if allowed to do this when sitting. Normally after 3 or 4 times cycling at the least to bring them back. You could have some cells going bad due to extended storage.

With my above assumptions, probably the best thing to do is cycle them a few times every 4 to 5 weeks at the max if you plan on storing them for future use. Although that does not help your situation now.

The bright side there are ways to make Nicads last longer and store them indefinately without babysitting them. Unfortunately you have to do some work and change the configuration from what you currently have.

Jeff