"Thom Stewart" wrote in message
...
John,

I have to agree with you. After years of using single batteries for
starting and running and other for House Battery and a single for
Inverter, I finally learned to start on two and run on both; just like
my truck camper. My Inverter wasn't hooked up to the battery switch so
that did need special attention. I've since done away with the Inverter
battery and paralleled it inverter with the house battery. They all get
the same charge. Works for me and cleaned up the wiring.

http://community.webtv.net/tassail/ThomPage

What I have found works well is to have a third battery (i.e., a starting
battery optimized for engine cranking as opposed to deep discharge) that is
on its own on/off switch, located as close to the engine as possible for a
short cable run and with significantly sized cable. (I'm using #00.) I only
turn this on for starting and for about the first 15 or 20 minutes of engine
running time (to make sure it gets topped back off after starting the
engine.) Then, I set my two Group 27 house batteries to the "Both" (i.e.,
paralleled) position and switch off the starting battery. (Important to do
it in that order so as not to fry the alternator diodes.) These Group 27's
are identical batteries of the same age and have always been run in parallel
so (hopefully) they have been discharging/charging at more or less the same
rate. Plus, by always running them in parallel I tend not to suck either
battery down too low, as opposed to, for example, seriously depleting
battery #1 and then switching to battery #2.

Regards,
Alan Gomes