Re: NiCd Battery Storage

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi gary,

On 21 Aug 2002, at 11:49, Tesla list wrote:

> Original poster: "Gary Peterson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <glpeterson-at-tfcbooks-dot-com>
> 
> To the list,
> 
> I read that NiCd batterys should be stored uncharged.  Is this still true
> for older nicads that have been charged and discharged a number of times?
> What about storing a newer battery that has seen only one or two
> charge/discharge cycles?

I don't think the number of cycles matters. The problem with charged 
cells is that they internally discharge, growing dendrites which 
eventually short them out. I'd discharge them to the point where one 
cell hits a volt (still with the correct polarity). Just reflecting 
on it, I'd be tempted to discharge the lot connected in parallel so 
reverse charging of a cell won't occur. I'd use a discharge current 
of no more than a tenth of the A-H rating of the lot connected in 
parallel.
     I don't like NiCads much anymore. I've fixed countless pieces of 
gear which have had them give off vapours and cause corrosion of 
other metal parts. It seems that once this has happened, you can 
never get rid of the effects. I've dealt to one flashgun three times 
and know I'll be seeing it again. Besides, the terminal voltage is 
inconveniently low for most equipment which has been designed for the 
nominal 1.5V/cell.
  
Regards,
malcolm