I have tested voltage on rear of fridge. Before compressor kicks in the volts are same as battery. When compressor is running the volts immediately drop by 0.70 volts at the fridge and then after about 2 minutes it went down to 11.32 volts and the battery voltage dropped by .28 volts and was steady at 12.48 with the compressor running. So numbers east to see.
Battery volts 12.76 compressor not on
Battery volts 12.48 compressor running
Fridge volts 11.32 compressor running
12.76 compressor not running.
Should there be that much volt drop to fridge?
Battery volts 12.76 compressor not on
Battery volts 12.48 compressor running
Fridge volts 11.32 compressor running
12.76 compressor not running.
Should there be that much volt drop to fridge?
DC voltage drop is normal and will be dependent an the cross section of cable and length of cable (both ways). Is the fridge running ok on fixed wiring?
Unfortunately I'm working today so I will have to run some tails tommorrow now. I'm going back to my original thoughts its battery or voltage related. It had gone warm again this morning. It's like the voltage must drop slightly below what it will operate on so I think running those tails will hopefully then prove the wiring through van.
That's quite a voltage drop. Our Dometic apparently draws quite a lot of current when it starts, but is very efficient when running. I had heard of issues with these fridges not starting up due to voltage drop, so put in some hefty dedicated wiring just for the fridge.
Pete
Pete
I have just made a less up ready to plug on a spare leisure battery I have. I was going to run it from the leisure battery in the van but I thought I would try it from another battery. This evening the voltage on the leisure battery was crashing as the compressor kicks in to around 10.2 volts from 12.6 volts. But it's hard to measure as compressor literally kicks in and then fridge comes up with error so shuts itself off. That's when I decided to run straight from another battery. I need to sort something. I'm not sure whats going on but something is definitely not right. I'm starting to wonder if it's a bad earth somewhere but I suppose once I wire fridge to the spare battery that's guna hopefully prove if it's the fridge or something else.
I have a Dometic 80crx fridge, when the voltage drops below a certain voltage. it turns off. The exact figure is in the manual.
Your battery might die under load when the compressor comes on. If it works off another battery then obviously it's your leisure battery, loose connections or earth, since it used to work with existing cables.
Your battery might die under load when the compressor comes on. If it works off another battery then obviously it's your leisure battery, loose connections or earth, since it used to work with existing cables.
Forgot to mention my battery will drop from say 12.6v to 12.4v when compressor is on then go back up to 12.6v when compressor shuts down , it shouldn't drop as much as yours.
Battery suspect or loose connections
Battery suspect or loose connections
Easy to check cables if you suspect the problem is in the wiring. Measure the voltage drop across each side of the circuit separately.
i.e. With all original wires in place, put your meter +ve lead on leisure battery +ve terminal and meter -ve lead on +ve connection on fridge. Any reading in that scenario will be the volt drop in the +ve connection to the fridge
Conversely...
Put your meter -ve lead on the leisure battery -ve terminal and meter +ve lead on the fridge -ve terminal which will give you the volt drop in the -ve circuit.
You may have to switch your meter down to a more sensitive scale if it's not the auto ranging type.
For those of us who have owned 6v Beetles we've done this many time to eliminate the volt drop problems in elderly electrical systems!
i.e. With all original wires in place, put your meter +ve lead on leisure battery +ve terminal and meter -ve lead on +ve connection on fridge. Any reading in that scenario will be the volt drop in the +ve connection to the fridge
Conversely...
Put your meter -ve lead on the leisure battery -ve terminal and meter +ve lead on the fridge -ve terminal which will give you the volt drop in the -ve circuit.
You may have to switch your meter down to a more sensitive scale if it's not the auto ranging type.
For those of us who have owned 6v Beetles we've done this many time to eliminate the volt drop problems in elderly electrical systems!
I done that yesterday and I had about .50volt dropped across negative and around 1volt on positive.
It seems as though fridge is fine. It runs lovely off of the other battery and only drops about .30volt when compressor kicks in. I'm just guna wire my new wiring across to the battery in the van now and that should prove existing wiring to fridge. If it still happens I suppose I will change the batteries over and see what happens then. This is a huge process of elimination. Thanks for all the tips. I'm so glad I didn't buy another fridge.
When my 130ah leisure battery was dying it would charge up to 12.8 v or so but when under load it would drop to 10.5v. My fridge would cut out due to undervoltage. I had to buy another agm deep cycle battery then all good. My original 130ah battery was a cheapy supplied by the campervan convertor . I replaced it with a quality 120ah battery that holds a charge heaps better.
Ok. I've now bypassed the existing wiring and all working fine by the looks of it so I'm going to replace wiring. What size cable should I use. It's probably 2-3 m from under rock and roll bed to the fridge. I have just used a bit of 2.5mm twin and earth but obviously I need to use multi strand flex but i wonder what size to use. Should I go bigger?
4mm2 or 6mm2 would be a better size, ideally you want minimal voltage drop between battery and fridge. With your jumper setup what voltage did you have at the fridge when compressor is running, you dont want much difference between battery and fridge. if voltage is the same but too low that points to your supply battery. If battery stays high but fridge voltage is low then your cabling or connections are suspect.
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