Saturday, Mar 01, 2014 at 13:35
The auxiliary battery will always accept some amp flow when fully charged, perhaps not much but a little + you will have the 10 to 15 amp fridge running off the supply wire.
As mentioned above, the vehicle wiring will be a bare minimum (manufacturers don't fit big wire to anything) to run small stuff and nothing like the load of the fridge and a battery.
Therefore, the wiring will act as a resistor and lower the alt voltage to the fridge resulting in the fridge barely performing and also the aux battery becoming discharged to some degree.
The success you have had in the past may not have detected the loss of charge from the aux battery in such circumstances, so it seemed to be OK but wasn't really working
well.
Unfortunately, 3way fridges take a long time to start cooling after stopped, and then have to play catch up in order to TRY and pull down internal temp.
So, effectively, for a long time after restarting the fridge on the 12v (even with and excellent 12v supply) the fridge won't be cooling for a large part of your journey and you then arrive with the fridge just beginning to do it's stuff. Hardly good for the food inside. Warm beer each day.
Been there done that, had two 3way fridges which both failed internally despite tender care and now only regard them as sort of ok if camped for long periods or at the holiday
shack.
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