"Wayne.B" wrote in message
...
On Sat, 11 Aug 2007 09:47:02 -0700, "Paul" wrote:

Jeff, it sounds like you are mixing Amps and Amp-hours. I'm sure you know
the difference, but it does make things confusing. For example, my refrig
draws about 5A when running, which it does perhaps 6 hours a day in the
tropics. This gives a 24-hour consumption of 30 Ah (at 12V).

That sounds incredibly efficient. What size box do you have and what
kind of system? Holding plates? Compressor type?

I have a Seafrost BD12 compressor/cold-plate (air) system, and the box is
perhaps 6 cu ft (I am trying to picture it, and this is merely an estimate).
It is reasonably well-insulated, but not spectacularly so. I usually put a
foam insulation sheet on top of the counter/lid to reduce the thermal loss.
I have measured the current drain, and it is indeed 5A. I have not
carefully measured the cooling duty-cycle, so I may be off a bit on the
daily AH. I don't think that it runs more than 1/3 of the time, though (8Hr
per day * 5A = 40AH) -- the compressor is in a locker in the aft cabin,
where I sleep, so I do know when it is running. It isn't a freezer, but it
can make ice cubes, and will keep a small amount of stuff frozen for a
while. The boat is a Pacific Seacraft 44.

Let's just say I put out these numbers as an example of AH calculations, not
necessarily an accurate measurement of my system's power consumption.

-Paul
-S/V VALIS
..