Fridge problems

[Delphinus]

We are living on board a Bavaria 44, the fridge works fine on shore power and when the engine is running, however if we are on battery then the fan works and the fridge constantly kicks in and out but without cooling the fridge. The batteries are 2x140 amp hour, brand new and the charge on the bateries never drop dramatically, my suspicion is wiring on battery is notcorrect, any suggestions?

 

[SeamanStaines]

Possibly its either bad connections on the cables or more likely, not a sufficently 'thick' cable going to the fridge. I suspect that you have voltage drop going to the fridge, so when running on shore power (or with the engines running you have between 13v and 14v at the batteries and, with bad cabling maybe dropping to 11v or 12v. When running on the batteries the voltage will drop to between 12 and say 12.7v so you could end up with as low as 9v at the fridge, which would make it cut out.

Easy to check with a meter

 

[nimbusgb]

Wires to the fridge may be undersized, when on shore power the voltage at the fridge compressor is sufficient, when on batteries it's marginal. Also ageing connections in the wiring or contacts in the fridge cct breaker or isolator switch could be introducing just enough resistance and thus voltage drop to cause a problem. Check voltage at the compressor with a decent meter.

To test, run a pair of reasonable weight wires direct from the battery to the fridge compressor observing correct polarity. If it works then start examining the above components.

 

[SeamanStaines]

snap!!

 

[Mrnotming]

Be sure Delphinus to let us know if any of these hints worked!

 

[superheat6k]

Mine was doing just this recently - dirty fuse ends.

 

[Tony Cross]

Wires to the fridge may be undersized, when on shore power the voltage at the fridge compressor is sufficient, when on batteries it's marginal. Also ageing connections in the wiring or contacts in the fridge cct breaker or isolator switch could be introducing just enough resistance and thus voltage drop to cause a problem. Check voltage at the compressor with a decent meter.

To test, run a pair of reasonable weight wires direct from the battery to the fridge compressor observing correct polarity. If it works then start examining the above components.

+1

I had exactly this problem. In the end I ran new cables (suitably sized) from the switch panel to the fridge, it's been perfect since.