Originally Posted by KJINTF
I would guess that the current draw from a 12Vdc source is very high and could easily drain even the largest battery system. Costs money to add the 12Vdc heating coil to the refrig and the extra fuse and heavy duty wiring to the coach
Very good guesses, Very very good in fact. Plus one more issue NOTE that this all affects the "Bottom line" as well.
In days of old Gas engines (And Diesels) had GENERATORS, not alternators, Now, I would rather not go into all the differences but it was around 1960's that they came out with the first Alternators.
Generators were kind of hard to kill, for one thing the regulator controlled the maximum current they put out, and did it very well.
Alternators.... Do not have externl current regulation and thus rely on internal regulation.
They are designed to do a quick recharge of the starting battery.
Providing over 300 watts (roughly 30 amps) constant load to the fridge. Not really in their design spec.
Early alternator failure was one side oe effect of the 3-way Fridge.
But the 6 to 8 G wire is a high cost item too.