On Wed, 11 Aug 2010 20:46:16 -0700, Don Hanson <dhanson928@GMAIL.COM> wrote:

>  The one in my van stays on propane always.  Don't even know if it works
on 12v because it works really well on propane and my battery never goes
dead......and 12v fridges have left me with flat batteries, so I don't use
em.....Don Hanson

When using the Dometic refrigerator, if my driving involves frequent stops,
I too operate it exclusively on propane.  Continually opening and closing
the fridge door to alternate between 12-volt operation when driving and
propane when stopped, significantly compromises the ability to keep the
contents of the fridge cold. I also don't open the fridge to see if it's
cooling properly; for that I have the probe of a remote-sensing outdoor
thermometer permanently installed inside the fridge, with the wire exiting
through a hole in the case and running to the display mounted just below
the dash in front of the shift lever.  If the propane were to blow out
while driving (which it never does), the display would show a rise in
temperature without much delay.  It is also quite informative to note the
fridge temperature as it rises with the increase in ambient temperature as
the day progresses, and to note the difference in fridge temperature when
the driver's side of the van is in full sun, as opposed to when the
driver's side is in shade; there's a notable difference.

I will not attempt to defend driving with the propane in use, but for me
this most often only occurs when driving dirt roads on which I encounter
few other vehicles, so the risk of collision is minimal, with a resulting
propane leak even more so. I will note however, that I barely crack open
the valve on the propane tank to operate the fridge.  Thus should the
propane system downstream of the valve experience a leak for whatever
reason, the leak, though still potentially dangerous, would emit gas at a
very miniscule rate, decreasing the chance of an accumulation of gas and
its ignition. The volume of gas required by the fridge is exceedingly
small, as evidenced by the fact that the fridge will run for several weeks
on one tank of propane, so this in no way compromises fridge operation.
When driving with the fridge operating on propane, one must consider it a
possible source of ignition of gasoline vapors whenever your vehicle or one
nearby is being fueled.  While possibly unlikely, one would not want to be
wrong about this.

For highway driving at speed and some distance, with few stops, I switch to
12-volt operation, which as everyone should know, is only available when
the alternator is producing power, that is, when the engine is running.  So
Don, I'm curious to know how it is that you have experienced flat batteries
running the fridge on 12 volts?  Have you altered the factory wiring
configuration for the refrigerator?

Bill