Inverters

G'day Peter

3 way fridges such as yours have a 12V and 240V heating element, both of which do a similar job. From my recollection of one we had a few years back, the 12V system bypassed the thermostat so it ran full chat all the time which could be your problem, notwithstanding that it's a tad unusual as they are notoriously woeful on 12V. I think, but I'm not sure, that the 240V utilises the thermostat so you could give it a try, however it's a fairly inefficient way to do so, considering the losses in the inverter and the safety issues to consider with 240V. Remember the old adage ........... "One flash and you're ash".

Another suggestion would be to wire in a relay as a switch for the 12V wiring, accessible from the driver's seat. Then you could simply turn the fridge off for a while to keep it from getting too cold.

Peter,

It's a 3 way absorption fridge which works off heat - great on gas, or can run off 240 volts using a big electric element. On 12V though there is another electric element to provide heat, enough to keep things cold but no more than that since electric heating is very demanding of electricity. This 12V element will draw about 12-15 amps continuously, which will 50% discharge a 100 Ah battery (typical size in a van) in a few hours. A battery simply cannot deliver the power that you need for serious cooling in a three way fridge.

Would it help to run the 12V through an inverter to get 240V for the much bigger 240V heating element? No way! The energy is still being drawn from the battery, but now the load will be much bigger due to the higher demand of the 240V element (plus inefficiency in the inverter). While your battery might have managed 4 hours at 12V, it probably wouldn't manage 1 hour on the inverter.

Sorry - fact of life with 3 way fridges - they need lots of heat to keep them cold! Great on gas. Not a job for a battery, but can do a half-hearted job on 12V if drawing from the alternator while travelling.

Cheers

John

A quick trip to your local Fridgy and get a freezer thermostat with a medium tail.
Drill a SMALL hole just big enough to get the tail into the fridge and down to the bottom of it , insert tail and seal !

Then wire the 12v supply thru the thermostat and by trial and error get the best setting that suits you.

I did a similar thing to the Caravan fridge for 12v supply, after all no need to run the fridge's 12v supply if it's already cold enough.

Saved on power draw leaving more for the van battery as well.


Ron

Tried running mine off an inverter when travelling yrs ago it made no difference still ran like crap especially in hilly areas that's why I bought an Evakool compressor fridge which gives you better control of your temps and doesn't freeze things in the fridge in cold weather when your camping.