Re: NiCd Battery Storage

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

Original poster: "Brian by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ka1bbg-at-webryders-dot-net>

Hi, I worked with Arthur Huse who assigned a patent to Bosch for Ni-cad
batteries. His advice"use them or loose them" the reason is inexpensive
Ni-cad batteries, the separator and chemicals and plated metal parts corrode
and the seals loose the moisture. Some very expensive Ni-cads have been in
use for 30 years and still working fine. The result of hermetically sealed
container with expensive solid metal pieces inside.
My buddy a Master Electrician says run them down till they stop and then
charge. They use the same pak's of batteries day in and out and get 3 to 4
years out of a set! Instructions on my Hitachi drill says run em flat. cul
brian f.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, August 21, 2002 7:35 PM
Subject: Re: NiCd Battery Storage


> Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<davep-at-quik-dot-com>
>
> > I read
>
> Where?
> There is much 'hooey' writ about batteries.
>
> > that NiCd batterys should be stored uncharged.
>
> Last manufacturer's data i saw (NOT real
> up to date) was that either was OK, with a
> MILD preference for discharged.
>
> > Is this still true for older nicads that have been charged
>
> > and discharged a number of times?
>
> I've seen no data.  A charged battery, over time,
> will become a discharged battery, by itself.
>
> > What about storing a newer battery that has seen only one or two
> > charge/discharge cycles?
>
> Same answer.
>
>
> > What would be a good proceedure for discharging a battery pack?
>
> cf below, per manufacturers recommendation (last I
> had).
>
> > discharge until the output voltage drops off then stop,
>
> This one.  Specifically, look for a 1.2 V 'step'
> drop in battery (cf below) output.  (1 V drop
> is ok) then STOP.  eg a nominal 6 cell/7.2 v
> battery should not be discharged below (7.2-1.2)
> or 6V.  Reasoning:  one cell will drop out first,
> go thru zero V, then _reverse_ as the remainder
> force current backwards.  This is BAD for the
> reversed cell.  If discharging lots of current:
> VERY bad.
> (Yes: Manufacturers more or less match the cells.
> One will still drop out first...)
>
> > or continue discharging until current flow is minimal?
> I wouldn't.  cf above.  I'd expect damage.
>
>
> > BTW, I use 9 volt nicads for portable operation of a SSTC
>
> > pulse generator, and to run a MOSFET driver circuit.
> How many cells?
>
> 7? 8?
>
> 1) I'd be tempted to store them charged but NOT
> try to 'float' them.  Let them discharge by
> themselves.
> 1a) Lead-acids tend to be stored on a 'float' charge.
> This tends to overcharge and dry out nicads, leading
> to early death, leakage, etc, unless done VERY
> exactly...  Simplest is to 'leave 'em', next
> simplest _controlled_ (V- 1.2V) discharge.)
>
> 2) Minor point of usage:
> Cell: a single unit.
> Battery: A buncha cells.
> If dealing with individual _cells_, can discharge to
> zero.  If dealing with _battery_, BAD thing to
> discharge to zero, as this means some cells are
> having current forced thru backwards....
>
> best
> dwp
>
> ...the net of a million lies...
> Vernor Vinge
> There are Many Web Sites which Say Many Things.
> -me
>
>
>
>