Jim Dunmyer wrote:

> I'm not too sure I'd worry a lot about isolating the trailer and vanbatteries
> because of a "mismatch". They're charged by the same source anyway,aren't they?
> And why would you NOT want the extra AHs of the van auxilary batteryavailable to
> the trailer?
>
>

Jim,

My thinking in the mismatch is that the trailer batteries are two 4DLifeline AGM
(absorbed glass mat, which I'll describe later) batteries while thevan auxiliary
battery is the Optima AGM deep cycle Group 34 battery. This means thatif I connect
the trailer batteries to the auxiliary battery terminal on the isolator(with a
heavy duty spade connector which should handle the current) that Iwill essentially
be charging three batteries in parallel on that one terminal side,the three would
be the two trailer batteries and the van auxiliary battery. Since thean auxiliary
battery is a different size and type, it will charge at a differentrate. It is my
understanding that a battery bank consisting of mismatched batteriescan ruin an
alternator and/or batteries due to variances in the individual batteryinternal
resistances and charging rates, etc. Whether this will happen I donot know ut each
of these batteries was quite expensive and I hate the idea of riskingthis without
having a better feeling about the consequences. It still seems o methat I am going
to have to use a three battery isolator.

I just wrote an article about AGM batteries for the next issue of theVintage
Advantage (presently at the printers). An excellent primer and sourcefor this
technology is available at http:///www.dcbattery.com/lifeline2.html.

Now as far as running #4 wire to the trailer connector, I figured Iwould splice in
the largest physical size I could at the connector. Although this willresult in
some current carrying capability, the mere transport of the larger4 gauge cable
directly from a battery source and to the back of the tow vehicle shouldresult in
minimal voltage drop which is often a limiting factor for the chargeline.

Would like to know more about the fork-lift style connector, is thisa connector for
between the tow vehicle and trailer in place of the Bargman? I havenever seen this
used.

Tom H.