"Ken" wrote in message
oups.com...
I have a beard trimmer that runs on a Ni-cad battery that I recharge
about once a month when the battery runs low. Recently, the battery
stopped being able to hold a charge. I charged it for ~12 hours,
tested the voltage, and got zero. OK, fine, so I soldered in a new
ni-cad, and everything works fine now. The trimmer is only a few years
old, so I thought the battery died earlier than I would have expected.


Then I got to thinking about the charger, which is just a simple wall
wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart
charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The
charger is what came with the trimmer, and molded into the trimmer is
something about "use only charger # such-and-such", which is also the
number on the charger. So I'm sure that the charger is the one that
the manufacturer intented to be used with the trimmer.

Did the higher than expected voltage on the charger lead to the early
demise of the ni-cad battery? Should I find a new wall wart that has a
voltage closer to 1.2 V? If so, what current output should it have?
(I save each and every wall wart from every dead appliance that I have
ever owned, so I have a wide selection to choose from a box in the
attic, although I think most of them are 5V and up.)

Ken

Stick with the recommended unit. The open circuit measurement doesn't mean
much.

1.325 is the voltage of a fully charged cell.

For a longer cell life don't leave it in the charger all the time.