| Re: When 12 volts is not 9.6 volts
On Sat, 30 Dec 2006 21:40:25 +0000, Mike Ellis <news@mellis.me.uk>
wrote:
>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
I was afraid that it was going to be something elemental.
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