Vicki Powys wrote:
>
> on 7/6/02 4:29 PM, Walter Knapp at wrote:
>
> > >
> > Rechargable batteries should not be discharged below 1 volt per cell.
> snip
> >
> > If it's a nicad pac, fully charge it, let it set a hour or so and
> > measure it's voltage. Divide that by 1.35 volts/cell and it should give
> > you a good idea how many cells are in it.
>
> Walt and all,
>
> Those maths work out just fine with my home-made discharging system. My
> fully charged battery is around 6.3 to 6.9 volts (depending on the age of
> the battery). Divided by 1.35 equals about 5, so maybe there's five cell=
s
> in the battery. Don't discharge below 1 volt per cell? No problem, if
> there's 5 cells, that's 5 volts, and I'm discharging the battery only dow=
n
> to 5.5 volts under load (or 5.9 unloaded).
5 cells would be what I'd think too.
You might get a slightly better capacity pulling down the voltage a
little closer to 5. Though it probably carries a little risk.
>
> If Sony ever stop making their DAT batteries, I'll make up a multi-cell
> external battery, as described by Klas, and connect the terminals with a
> dummy battery made from a wood block, as described some time ago by someo=
ne
> on this list.
If you have a dead DAT pac, take it apart. Even if it's a glued together
job, a way can be figured to get it apart so that it can be put back
together. Once apart you can examine how it's made. As I've said, most
commonly these are just sets of off the shelf regular cells. Often the
part number is on each cell for a exact replacement. The hardest part is
that there may be a tiny thermal sensor glued in there that's part of
the charger control and will have to be carefully salvaged. It's
probably a thermister, and if it can be figured out they are easy to get
new ones. You may find it's cost effective to rebuild pacs even if they
are still available. You may even be able to make them better than new
with the addition of higher capacity new cells.
And depending on the charger you have it might even be possible to go
the NIMH in a pac, which would really increase capacity. You could
certainly do that by coming up with a external charger that matched the
new pac.
> By the way, the Sony mains charger does the job in two hours, and the car
> battery charger in one and a half hours. There is no slow-charge option =
for
> either.
This is getting to be very common. I don't consider it as big a problem
if the charger is matched to a specific pac as in this case. And a great
many of these newer chargers are microprocessor controlled, which gets
rid of a lot of the ways older fast chargers killed things.
Walt
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