Battery drain help with 240v compressor fridge needed....

[Dodgey]

Nice one! That's a bargain! (we'll my 60litre compressor fridge for £70 was a real bargain ).

The Danfoss BD35 compressor is the same one used in all Waeco, Coolmatic, Vitrifrogo, camper, boat fridges. It's the expensive bit. The rest is just an insulating box. (My coolmatic (Waeco) fridge uses the same compressor)

And it freezes too. Nice one.

[winchman]

Nice little 65w fridge in the sales section

[Waynem325]

Aaaaaaarrrgggghhhhhhh!

Spoke too soon!
It arrived midweek, and after plugging it in and switching it on all seemed well. It sounded like the compressor kicked in and the fan started up, but after 6 hours the temperature reached an amazing 29 degrees (centigrade)!!! Ambient temperature in the van was 45 on the dash.

Unsure what is wrong, although I suspect (or rather hope!) the coolant needs topping up???

There's a 'fizzing' noise from inside as if coolant is flowing through the pipework, but the cooling plate doesn't get cold.

Could it be just as simple as a coolant top up, and if so where can I take it to be done? There are no visible leaks or smells from within or around the fridge.
The seller apparently had the coolant topped up last year and it's been sat in his garage ever since.
Any ideas, or is it a lost cause?

I'm getting sick of fridges, but on the plus side, after 6+ hours the battery was still showing 12.6 volts!

[Simon Jones]

I wouldn't have expected a fridge would need regular topup of refrigerant. It sounds like its got a leak somewhere. My Waeco CF18 is about 5 years old now and works just as well as when I bought it and so far, has required no maintenance.

I would have thought any domestic or commercial refrigeration engineer would be able to look it over and top it up if appropriate.

[Dodgey]

With Danfoss compressors on Waeco/Coolmatic etc fridges - if the wires are not thick enough or the battery is low, it can sound like the fridge is turning on. The compressor fires up ("BBBBBBRRRRRrrrrrrrrrrr" sound - like a normal fridge) and the fan switches on, but seconds later, the compressor stops, but the fan continues. It will keep doing this as the voltage of the battery recovers a bit. The untrained ear, hearing the fan, will think the fridge is on.

Just a thought.

[Simon Jones]

Good point. The rear 12v accessory socket will not run a compressor fridge due to the voltage drop. Try it on a decent 12v power supply, or connect it directly to the leisure battery (via suitable fuse).

[Waynem325]

Cheers guys.

I suspected a knackered battery when I flattened it testing the consumption of a coolbox a few weeks ago. It still reads 12+ volts and receives a constant charge from the solar panel but it may not have recovered and could be questionable??? Having the fridge on whilst the engine is running would answer this question....just need to find time to go on a long enough run?

I bought an aux socket extension from Amazon purely for the use of the fridge, which clips onto the terminals of the battery, so I believe the wire is thick enough (can't remember what gauge now?). I do have thicker gauge wire in the garage somewhere which I will test.

Why is nothing ever straight forward with a Bongo???

[Dodgey]

The compressor draws a big spike in each startup. Thinner cable can't provide it in time and the inbuilt low voltage cut off in the fridge thinks the battery is flat, and switches the compressor off (but the fan still runs). This is why you need bigger cable than the fridge wattage suggests.

I've just rewired my fridge as it wasn't performing as it should and it's made a HUGE difference. It was cutting out after less than 12 hours at night time. I never noticed before as I have solar, so my battery shows pretty much full in the morning and during the day. I woke up at 5am last weekend to hear the fridge constantly going on and off. I know the sound of the low voltage cut off - My battery should be lasting for ever in good weather with solar. The fridge wasn't getting past 5am! - thing is, the rest of the electrics were fine - i.e. the battery was fine. TV, lights etc, all fine.

I had hefty cable going from the battery to the solar charger, and the same back to the fridge, but there were several places where it was interrupted with runs of 2.5mm2 (27Amp) cable, which I thought was enough. I've doubled up the 2.5mm2 cable and now my fridge is performing much better. I've disconnected the solar and I've had the fridge running for 24 hours so far with no cut outs at all.

Danfoss and Dometic both specify that for every metre of cable run to your fridge, you should have 1mm2 of cable thinkness. So 5 Metres = 5mm2 !

[Waynem325]

Aaaaah - thats interesting!
I have 4mm cable that I used for the solar panel (MC4) so will use that to connect the fridge directly to the battery and see what happens next?
Fingers are well and truly crossed!

[Dodgey]

Yeah - experiment . The solar actually doesn't need the size of the cable it comes with. The manufacturers assume we will be running long runs of cable. In a camper you can use 17.5amp 2mm2 cable quite happily. The loss equates to a fraction of a % over 5 metres.

My fridge testing is done. I got 48 hours out of a 100Mah battery with the thermostat at middle position (more than enough for the ice box compartment to freeze). This is with occasional radio use as well. Solar disconnected. With my old cabling I wasn't getting 24 hours with no solar.