By Richard Spelling
While researching a project (yes,
I have more projects than I have
time ... who doesn’t?), I decided
I needed to learn a little bit about
charging NiCd and NiMH batteries.
Now, that was some very
interesting reading. In particular, it
was mentioned by several sources
and manufacturers that NiCd and
NiMH batteries could be charged
500 to 1,000 times.
Now, wait a second here. Back in the day, I was
enamored by the thought of interchangeable battery packs,
and I bought quite a few Versapak tools. The batteries that
come with them say they are good for up to 300 charges —
not 500 to 1,000. My own experience, plus anecdotes from
friends that use them, would lead one to think that they
are good for MUCH less than that. In fact, I have had the
experience of buying new Versapak batteries, using them
once, sticking them on the charger, then when I went to
use the tool again, the battery would be completely dead.
I slowly came to the realization that the chargers for
the Versapaks burn up the batteries. If you leave them on
the charger — which is a natural thing to do in order to
keep them “topped off” — you will ruin the batteries.
The current that battery chargers charge with is
generally expressed as a fraction of the capacity of the
battery, denoted as “C.” So, for instance, the standard NiCd
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