12v/24v only Dometic fridge error that is causing me to tear out my remaining hair

[Duetto 1999]

Can you alter the cut in and out voltage.
My adventure one has 3 settings for this.
Off hand I cant remember them.
I'd also try a heavier cable. Then a battery test (not just a meter)
I'm no electrician.....just saying.

I don't think the cut-in and cut-out voltages are alterable but I have not yet managed to find the definitive manual for this model. I hope that when I remove it from the vehicle I will discover a plate telling me that information -- until then am a bit in the dark (as usual!)

Once on the bench at home (I am in France at the moment) I shall try all suggested remedies in the hope of proving @merl wrong about diagnostics and repair being a bit of a B****RD (I suspect, however, he is 100% correct). Meanwhile - thank goodness the weather here is so super chilly!

 

[1 Cup]

Mine was a dodgy fuse holder drop the spade connector wire to fridge to the lower fuse in junction box. /At the ten fuse box ! So liked swaped to 10amp fuse from 5amp
all good.

 

[merl]

I don't think the cut-in and cut-out voltages are alterable but I have not yet managed to find the definitive manual for this model. I hope that when I remove it from the vehicle I will discover a plate telling me that information -- until then am a bit in the dark (as usual!)

Once on the bench at home (I am in France at the moment) I shall try all suggested remedies in the hope of proving @merl wrong about diagnostics and repair being a bit of a B****RD (I suspect, however, he is 100% correct). Meanwhile - thank goodness the weather here is so super chilly!

Two things could be going on that would make the 'thin cable' theory work even though your multimeter displays otherwise.
1, your multimeter is inaccurate OR
2, The fridge motor tries to kick in, the load causes the voltage to drop to an unacceptably low level, the safety setting kicks in and the start process is abandoned, and all this happens so quickly that your multimeter doesn't detect or display the drop in voltage. Either way the meter isn't the best so maybe try using another if it you can just in case the voltage IS dropping out and your current meter isn't detecting/showing it.

 

[Robmac]

Two things could be going on that would make the 'thin cable' theory work even though your multimeter displays otherwise.
1, your multimeter is inaccurate OR
2, The fridge motor tries to kick in, the load causes the voltage to drop to an unacceptably low level, the safety setting kicks in and the start process is abandoned, and all this happens so quickly that your multimeter doesn't detect or display the drop in voltage. Either way the meter isn't the best so maybe try using another if it you can just in case the voltage IS dropping out and your current meter isn't detecting/showing it.

Obviously that is what I meant when I suggested voltage drop Merl.

 

[wildebus]

Two things could be going on that would make the 'thin cable' theory work even though your multimeter displays otherwise.
1, your multimeter is inaccurate OR
2, The fridge motor tries to kick in, the load causes the voltage to drop to an unacceptably low level, the safety setting kicks in and the start process is abandoned, and all this happens so quickly that your multimeter doesn't detect or display the drop in voltage. Either way the meter isn't the best so maybe try using another if it you can just in case the voltage IS dropping out and your current meter isn't detecting/showing it.

The level of power surge when the compressor kicks in surprises people. For a fridge that draws around 50W when running, that initial surge can be in excess of 800W, which is why the cable needs to be much thicker than the fridge specification would suggestion and some installers realise.
The fridge not turning on due to low voltage even though the battery is good is a very common situation due to incorrect installation and is invariably the cabling.
A quick and easy test is the one I mentioned ... See what happens with the engine running.
This will put the battery at at least 1V higher, so while you still get the voltage drop occuring, the fridge-end voltage will be higher - and high enough not to report a low-voltage situation.

 

[Duetto 1999]

ha ha, I saw that the voltage was tested at the fridge in first post but I would still run additional/heavier cabe to test as a first step lol

I have to say that I too like the "Occam's razor" approach (to this as well as everything else in life!).

 

[Duetto 1999]

The level of power surge when the compressor kicks in surprises people. For a fridge that draws around 50W when running, that initial surge can be in excess of 800W, which is why the cable needs to be much thicker than the fridge specification would suggestion and some installers realise.
The fridge not turning on due to low voltage even though the battery is good is a very common situation due to incorrect installation and is invariably the cabling.
A quick and easy test is the one I mentioned ... See what happens with the engine running.
This will put the battery at at least 1V higher, so while you still get the voltage drop occuring, the fridge-end voltage will be higher - and high enough not to report a low-voltage situation.

Engine running won't help - no connection between motor battery and leisure battery but see my post above - the cable test will be the first port of call

 

[Robmac]

I have to say that I too like the "Occam's razor" approach (to this as well as everything else in life!).

I like that, I'll try and work it into a conversation next time I'm in the pub.

 

[Robmac]

Can I ask why you don't use the alternator to charge your leisure batteries?

 

[wildebus]

Engine running won't help - no connection between motor battery and leisure battery but see my post above - the cable test will be the first port of call

If you are only using Solar Charging to run your compressor fridge, then that in itself will become an issue down the line when the harvesting starts to drop off.

To be frank, your "new to me" Camper sounds like it needs a bit of a rethink to how the stuff works

 

[Robmac]

If you are only using Solar Charging to run your compressor fridge, then that in itself will become an issue down the line when the harvesting starts to drop off.

To be frank, your "new to me" Camper sounds like it needs a bit of a rethink to how the stuff works

My thoughts as well David but maybe they only use sites with EHU?

Or maybe another cunning plan...

 

[wildebus]

My thoughts as well David but maybe they only use sites with EHU?

Or maybe another cunning plan...

If the only charging of the Leisure Battery is via Solar, even EHU won't be any use for the Fridge, the Water Pump, the Toilet Pump, the LED Lighting, the .....
Maybe making a sweeping statement, but sounds like a conversion that was done as 'easily' and cheaply as possible - so no cabling from engine battery to have B2B or Split-Charge (seen that before on a 'professional' conversion, and from description given, no mains charger - which means of course anything 12V will get no benefit from EHU.

You never really know what you have on a "new to me" Camper and first thing is spend some time getting to know it and work out what works and what doesn't work before you set off on a holiday

 

[Robmac]

If the only charging of the Leisure Battery is via Solar, even EHU won't be any use for the Fridge, the Water Pump, the Toilet Pump, the LED Lighting, the .....
Maybe making a sweeping statement, but sounds like a conversion that was done as 'easily' and cheaply as possible - so no cabling from engine battery to have B2B or Split-Charge (seen that before on a 'professional' conversion, and from description given, no mains charger - which means of course anything 12V will get no benefit from EHU.

You never really know what you have on a "new to me" Camper and first thing is spend some time getting to know it and work out what works and what doesn't work before you set off on a holiday

Without reading back through I thought he said that the Leisure Battery wasn't charged from the alternator, but maybe he has a charger linked to the EHU? Or possibly a power bank? I'm sure all will become clear.

If ever I fitted out a van again it wouldn't even have leisure batteries. Lights, shower etc. would be rechargeable and a 12v rechargeable coolbox would be charged whilst driving, I would also add a powerbank with Solar.

I like minimalism - Julie doesn't!

 

[Robmac]

Without reading back through I thought he said that the Leisure Battery wasn't charged from the alternator, but maybe he has a charger linked to the EHU? Or possibly a power bank? I'm sure all will become clear.

If ever I fitted out a van again it wouldn't even have leisure batteries. Lights, shower etc. would be rechargeable and a 12v rechargeable coolbox would be charged whilst driving, I would also add a powerbank with Solar.

I like minimalism - Julie doesn't!

Minimalism is the wrong word, I should have put 'I like simple...'

I also wouldn't have a gas system, just a camping stove. Not very economical granted but nice and unproblematic.

 

[Fisherman]

If the only charging of the Leisure Battery is via Solar, even EHU won't be any use for the Fridge, the Water Pump, the Toilet Pump, the LED Lighting, the .....
Maybe making a sweeping statement, but sounds like a conversion that was done as 'easily' and cheaply as possible - so no cabling from engine battery to have B2B or Split-Charge (seen that before on a 'professional' conversion, and from description given, no mains charger - which means of course anything 12V will get no benefit from EHU.

You never really know what you have on a "new to me" Camper and first thing is spend some time getting to know it and work out what works and what doesn't work before you set off on a holiday

Nail on head, David.
Somethings not right here.
Why would you not use your alternator to run your fridge when driving.
I think the OP needs to look at the bigger picture here, things just don’t seem right with this van, this may not solely be a fridge issue, but an issue involving poor conversion.

 

[merl]

The level of power surge when the compressor kicks in surprises people. For a fridge that draws around 50W when running, that initial surge can be in excess of 800W, which is why the cable needs to be much thicker than the fridge specification would suggestion and some installers realise.
The fridge not turning on due to low voltage even though the battery is good is a very common situation due to incorrect installation and is invariably the cabling.
A quick and easy test is the one I mentioned ... See what happens with the engine running.
This will put the battery at at least 1V higher, so while you still get the voltage drop occuring, the fridge-end voltage will be higher - and high enough not to report a low-voltage situation.

Just postulating here but when 'non starting ' would that voltage drop and recover so fast that a DVM wouldn't show it?
Have you ever tried measuring the voltage at the fridge under a 'non start' and if so what was shown at the meter?
Or is it more of an Occam's Razor situation (see what I did there Rob?) and you simply know from experience that it's a cable issue?

 

[wildebus]

Without reading back through I thought he said that the Leisure Battery wasn't charged from the alternator, but maybe he has a charger linked to the EHU? Or possibly a power bank? I'm sure all will become clear.

Could be the case - in WHICH case my suggestion of "start the engine" is simply changed to "plug in the mains charger" in order to boost the hab battery to perform the same test

If ever I fitted out a van again it wouldn't even have leisure batteries. Lights, shower etc. would be rechargeable and a 12v rechargeable coolbox would be charged whilst driving, I would also add a powerbank with Solar.

Sounds like you want a tent with wheels
I could not go down that route for a second. I like to be able to plug something in and have it work. individual batteries for individual devices would be a blooming nightmare!
Bad enough when you have to juggle batteries in remote controllers because you forgot to bring a spare set. Extend that to EVERYTHING and it would be hell! what names will you be called when the rechargable battery for the shower goes flat while in the middle of shampooing hair?

I like minimalism - Julie doesn't!

 

[1 Cup]

Mine was a dodgy fuse holder drop the spade connector wire to fridge to the lower fuse in junction box. /At the ten fuse box ! So liked swaped to 10amp fuse from 5amp
all good.

THE REASON THIS HAPPEN WAS WIFE TURNED SETTINGS UP ON FRIDGE !

Try turning it's setting knobs.

 

[colinm]

We where watching a Swedish couple in a lashed up Renault Traffic van, wife got out and sat reading whilst hubby ran around setting everything up outside to cook, in my imagination she had said "you wanted to save money on a lash up, you do the work"

 

[wildebus]

Just postulating here but when 'non starting ' would that voltage drop and recover so fast that a DVM wouldn't show it?
Have you ever tried measuring the voltage at the fridge under a 'non start' and if so what was shown at the meter?

Or is it more of an Occam's Razor situation (see what I did there Rob?) and you simply know from experience that it's a cable issue?

It's a cable issue almost certainly

The first test I would do is the one I said... Boost the Hab Battery voltage by whatever means available ... Engine Starting; Mains Charger, even jump leads from Starter Battery if need be, and see if the fridge kicks in then.
The typical symptoms for this situation goes along the lines of "The fridge always works when I am plugged in or driving and the first night, but it won't go on even though the battery is good and at 12.5V". Followed by "the installer checked the manual and says it draws 3A when running, and that 1mm cable is rated at 11A so plenty big enough".

If the cable is not a minimum of 4mm2 then there will be an excessive drop. and the longer the cable run, the thicker the cable needs to be. The 'Small Dometic Compressor Fridge' is probably a Waeco Fridge. Nice Fridges, but low-voltage intolerant and not adjustable as far as I am aware (certainly not in the past).
You get additional drops for every connection made, so a fuse is a voltage drop (but it is needed, of course); an additional handy switch to turn the fridge on and off is a voltage drop (NOT needed - the fridge has that already)