On Sun, 23 Dec 2012 16:58:39 -0500, JustWait
wrote:

I just replaced an 8D diesel engine starting battery (155 lbs, $325)
with a pair of the AGM 31Ms in parallel (75 lbs each). The 31Ms are
much easier for my wife to lift over the engine. :-) I've been
averaging about 2 years of life out of the 8Ds so the AGMs will
eventually pay for themselves if I can get an extra year or two out of
them.


Could you run a small cabin heater all night long with one of those
batteries?

===

Only if it was one of those wimpy little dash board heaters that plugs
into a cigarette lighter. A typical full-powered electric heater
draws over 1,000 watts which translates to over 100 amps at 12 volts
DC. You might get ten minutes if you were lucky and the battery
would age well before its time if you did it very often. What you can
do with an inverter and a big battery bank, is run an electric blanket
all night. We do that on the boat but our inverter runs from (8)
heavy duty golf cart batteries, about 1,000 amp-hours total.