| Re: When 12 volts is not 9.6 volts
dgk wrote:
> I like to use rechargable batteries in my lights, and for the most
> part using a rechargable AA in place of a regular battery works fine.
> But with cold cathode bulbs on my bike, the little transformer thing
> needs 12 volts. So I replaced the normal 8 AAs with 8 rechargables.
> And it sort of works. But one bulb starts dimming after a half hour or
> so. Checking with normal batteries, this doesn't happen.
>
> I looked a bit closer at my rechargables, which are, it turns out, 1.2
> volts, not 1.5 like regular batteries. All rechargables that I looked
> at are 1.2. So, 8 * 1.2 = 9.6, not 12. Other stuff, like CD players,
> work fine on the rechargeables, but the cold cathodes have a bit of a
> problem. Obviously, 10 batteries instead of 8 should do the trick, but
> I don't have, and can't find, a case that holds 10 batteries.
>
> So, why do some things work fine with 1.2, and others not? And why
> aren't rechargeables 1.5?
Some things work fine whilst others don't because the application isn't
so voltage critical. It could also be that the internal circuitry
reduces the input voltage to a lower value so that lower voltage cells
will work. The reason that rechargeables are only 1.2 volts is because
the chemical reaction only produces 1.2V whereas the chemical reaction
of regular batteries produces 1.5V. I'm afraid its all down to the
chemistry.
Mike
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