Outer Limits 4x4 Board

I have a waeco fridge that when my dual battery drops below 12V the compressor will not fire up.

I can hear the compressor trying to fire and the volt meter needle goes down to 8v and then jumps back up to 11.5 and it tries to draw enough power to start up..

What is the normal voltage required to get the compressor going?

Is my fridge faulty or is it just the norm?

Thanks in advance for any help

Paul

I think you've got a bad (high resistance) joint somewhere in your supply line - the compressor start current creates a voltage drop across the high resistance, so the voltage at the fridge drops and the compressor cuts out. Once the current stops, the voltage comes back up, and the cycle starts again.

8V is a typical battery terminal voltage during engine cranking. Your Waeco DOES NOT draw that much current.

Disassemble and reassemble all your connections and try again. If you've got a voltmeter, check the voltage everywhere you can while the fridge is trying to start - it should be easy to isolate the problem.

Sounds like you have to upgrade the size of the wire to your fridge!

I am running 6mm at the moment which I am told should be enough

I am going to check all my connections on Tuesday and see if thats the problem.

I have only recently fitted an anderson plug on the fridge so it might be the connection there.

Thanks for your help

Could also be a bad earth....

Secondary earth to the chassis through the rear of the vehicle could be corroded.

Where are you measuring the voltage from??? Try it at the battery (direct across the terminals) and also at the outlet in the rear.

If you really want to be clever, find a decent earth point on the chassis near the rear of the vehicle and measure the voltage between that and the negative terminal of the outlet with the fridge connected. The result SHOULD be zero volts. If it isn't then you have issues with the earthing from the outlet to the chassis, and if it is zero, then you should be looking at the positive supply rail.

your waeco fridge most likely has a Danfoss compressor fitted. These have a low voltage protection. The symptoms you describe are exactly what occurs when the low voltage protection is activated and is normal (if your battery level is low). The low voltage protection is adjustable. I am unsure what setting Waeco sets them too. From memory the factory setting from Danfoss is cut out at 9.6V and cut in at 10.9V. It sounds like your battery voltage was too low.