troubleshooting a very warm fridge

[screwfix]

Hi, we’re running a 12v fridge off 3 leisure batteries connected to solar power. Though the fridge worked fine for the first week on solar charge, it’s now cutting out whenever we plug it in. It starts for 5 sec then shows error message ‘Not enough voltage’ - however, as per the manual the voltage cutout should be about 10.5v and we’re consistently putting out ~ 13.8v. We have a power inverter and are considering plugging it into that, but that’s not ideal. We also have plugged it into the car batteries and it runs fine, and we’ve used that to bring it down to the correct temp before plugging it back into the solar but still no luck. If anyone knows any solutions it would be much appreciated, we contacted the manufacturer and they said they couldn’t help with the electronics (we just want cold beers in this heatwave again!). We can post some diagrams if necessary, TIA

 

[Diver300]

It sounds like the voltage is dipping when the compressor tries to start.

Three possible reasons come to mind:-
1) The fridge is taking more current than it should
2) There is poor connection somewhere between the batteries and fridge.
3) The batteries have degraded and are higher resistance than they should be.

Try connecting an ordinary 55 or 60 W halogen bulb in place of the fridge. It should light immediately. If not, the problem is 2) or 3)

 

[Ian Rogers]

I agree... The battery pack cannot deliver enough current.... What battery pack is it? A car battery can provide a lot of current, upwards of 300A.. If the battery pack contains the smaller batteries ( ie the very small lead acid types ) 12v fridges consume around 30 ~ 50 amp per day.. The fridge will also take a large inrush current on starting the compressor ( as Driver already stated ).

 

[Externet]

Follow those very valid suggestions above ^
Use an automotive battery for the fridge system. Measure voltages when running or attempting to run. Are the solar panels 30 or more cells ? Is there something in between like a 'solar charger' ? Are ALL connections clean and firm ? Compare solar watts to fridge watts. Full sun ?

 

[Nigel Goodwin]

Either the batteries are duff (people commonly try and use old faulty batteries for such purposes), or (more likely) the solar panels are too small to keep the batteries charged up - again, it's common for people to hugely over estimate the capability of solar panels, and the imaginary specifications provided by the sellers/manufcaturers doesn't help.

How big are the panels?, and what is their 'claimed' output?.

Basically you want LARGE panels, aligned correctly on the sun (you don't need to steer it, just point it at the sun at midday), and a proper charging system.

What kind of charger are you using as well?.