> Can you explain the process of electro-shocking batteries? All of
> my 9.? batteries for my Makita drill are lousy at taking and holding
> a charge. Eventually I'm going to pick up something else but if can
> keep the Makita going, so much the better.
This applies only to Nickel-Cadmium batteries, and only to packs that cannot
be charged to their normal "full charge" voltage, because one or more cells
in the pack are shorted. It doesn't always work, and I'm sure there's some
potential for personal injury.
What happens is that as NiCad packs get older, the individual cells lose
capacity at slightly different rates. If one cell runs down before the
others, the voltage on that one cell can go negative, which causes an
internal short in the cell. The idea is to burn away the shorted area,
leaving the rest of the cell functioning. Of course it was the weakest cell
to begin with, and you're going to burn away even more of it's capacity, but
it still sometimes leaves a functioning pack. You'll want to be careful to
not run the pack all the way down in the future, or the cell will short
again.
Take a sizeable capacitor ... exact size isn't important, I've used as
little as 100 mfd and had it work ... and charge it up to several times the
rated voltage of the pack paying attention to the polarity of the cap. Then
discharge it suddenly through the pack, again paying attention to polarity
(positive to positive). I generally repeat this twice and then try charging
the pack again. If the pack voltage comes up to nominal, then give it a
nice long charge to try to equalize the cells. If not, you can try the
shock again if you want. It's sometimes taken me 3 or 4 tries to get a pack
back (and sometimes it doesn't work at all).
As it happens, I have a large adjustable DC power supply on my bench that
has capacitors on the output. There's a circuit breaker to protect the
supply against shorts, but the capacitors are on the output side of the
breaker. So, I just crank the voltage up to 30-40 volts and touch the leads
to the battery pack. The breaker pops, but the pack gets the jolt.
YMMV
Randall
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