On Thu, 14 Oct 2010 08:43:16 -0400, Wayne.B
wrote:

If you want normal life from your inverter batts it is important to
limit the discharge level to less than 50% (about 11.7 volts when
under load). The net result is that you need twice as many amp-hours
as your energy budget, perhaps more if your recharge time is limited.
It take quite a while to bring the charge level back to a full 100%
because the acceptance rate tapers off once you are above about 80%.
A good design point for A-H capacity is 3 times your energy budget.

Wayne, the 50% rule doesn't really apply to golf cart batteries. Back
in my electric car days there was a "trick" we used when we were
stupid and came to a stop from totally discharged batteries. Wait 10
to 20 minutes for the batteries to "self charge", then play
egg-on-accelerator and we'd get another mile or two. Wait and repeat.
Sometimes it took three or four of these cycles to get home.

Having said that, it's a good idea to limit to 20%, simply because
most inverters will shut down around that point.

A good point on taking a while to bring to a full charge. A lot of
folks think you can just pump in the Amps with a big alternator, but
it doesn't work that way in the real world.

A bit of golf cart battery advice. There are two battery manufacturers
in the USA, and they pretty much do the same thing. We bought the
same batteries from Sam's for $72 each as the local dealer had for
$160 each. By same I mean the same brand and model.

Re microwaves and coffee pots. It boils down to personal preference
and the boat systems. In our case we had enough solar so it was "free"
renewable energy as opposed to burning propane that we had to replace.

Rick