[SunRescue] An intriguing idea...

[BSD Bob]

> So, just HOW DO you get nicads to last 20 years?  Is your technique
> applicable to smaller batteries such as those found in screwdrivers and
> phones and radio control transmitters & receivers?

It only works on wet nicads.  The usual dry things just aren't worth doodoo.

> What about cycling?  How often?  What's the 'best' way?  What's an
> acceptable (and cheap) way?  Should they be left long periods in a charged
> or uncharged state?  If left charged for a long period, should they be
> discharged before recharging or is 'toping them off' OK?

I wrote a paper on the subject a few years back.  It used to be on
ftp://piobaire.mines.uidaho.edu/pub/Glowbugs/Articles/batterie.ps.gz.

Wet nicads don't really require cycling like other things do.
The sluggishness has never occurred in my hands on wet nicads.
It is proper to do a topping-off charge periodically, such as
every 4-6 months at something like C/10 x 1.20 to insure that
the batteries maintain full charge.  Alternatively, a float
charge of C/100 to C/400 will do the same thing.

I cycle my cells once every 3 or so years, and use them for
Field Day emergency operations yearly.  Other than that, I
don't do much to them.  They sit for months at a time, and
I just do the topping off.  I suppose I should probably refluid
the cells (they are supposed to be drained and refluided every
10 years although I have never needed to do that on mine).
It is important to keep proper water levels in the cells, though.
Cycling is just putting a 12 or 24V lamp or motorgenerator
load on them overnight or such, and recharging at C/7 x 1.20.

Bob