On Fri, 04 Jul 1997 09:37:56 -0500 Mark Endicott <endicott@bellsouth.net>
writes:
>Some thoughts on dual batteries:
>
>First of all you will gain nothing by using two 12 volt batteries in
>parallel versus two 6 volt batteries in series if the batteries are
>about the same physical size. For instance a given amp hour rating for
>a
>6 volt battery may be 200 amp hours, and the same physical size 12
>volt
>battery will have an amp hour rating of 100 amp hours. Since it will
>take two 6 volt batteries to develop the 12 volts we need they will
>retain the 200 amp hour rating. Using two 12 volt batteries in
>parallel
>will double the amp hour rating, but still you will end up with 200
>amp
>hours. The only advantage of using two 12 volts would be to use a
>large
>switch (200 Amp)to keep one battery as a spare in case the other was
>discharged. That's what we do on boats because they are real hard to
>push start. Charging two twelve volt batteries with diode isolation
>is
>a compromise at best. The voltage drop across a diode is .7 volts and
>this will not allow your battery to reach full charge unless the
>regulator is adjusted to compensate for the loss. There are some
>expensive devices that sense voltage on two batteries, then direct the
>charge current to the battery that needs it through a relay. These
>eliminate the losses and work good, but at a high cost.
>
Gee, wouldn't it be a whole lot easier just to park facing downhill?
Rick Morrison
72 MGBGT
74 Midget
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