Military-Vehicles: Re: [MV] Battery Question

Re: [MV] Battery Question

SBJohnston@aol.com
Sun, 20 Jul 1997 10:24:54 -0400 (EDT)

I wrote earlier:

>>It can cause problems if series batteries are different.

Richard (106363.2514@compuserve.com) wrote:

> Very good advice and applies to the vehicle charging also.

That's a good point -- since the current thru the series batteries has to be
the same thru both, one will be subjected to a higher proportion of the
charging voltage than the other, according to their internal resistance. If
they are very different, one will likely take a beating and die sooner.

> Don't be tempted either to use "half" the battery to run
> modern 12v devices.

Perhaps this *could* work if very careful attention is paid to regulation of
the voltage presented to the 12v equipment. But it is a real trick is to
design a circuit that passes the 12v or less from a bare battery, yet
protects againsts the elevated charging voltages that could come along when
the engine is running. Most common regulator circuits wouldn't work under
all circumstances -- they require a higher voltage on their input than the
desired output.

But wait a minute... if you are going to build a regulator, just regulate the
whole 24v down to the 13.8 you need for the *modern* equipment. That's the
best bet.

Steve Johnston

sbjohnston@aol.com

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"If you cannot convince them, confuse them."
- Harry S. Truman
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