Confused why my Dometic car fridge not working well!!
DogBoyz said
07:50 PM Apr 2, 2025
I am frustrated to the bloody max with this stupid solar / car fridge bullcrap
My spare battery in back of my Kia Carnival (2006) is not lithium. Just a big old battery in a black box
But it was running my car fridge which is only 1 yr old. Dometic CFX
then one day it all changed.
I have a Victor MPPT controller. Anderson plugs and all that.
right now the dometic app says my battery is 12.9v
but my fridge is 16c when it is set to be -1c.
at night or if i park under a tree fridge goes from 16 to 20 something.
It used to work really good. Nice cold drinks.
If the battery is 12.9 does that mean battery is good? If so, why does temp go up at night so much and battery falls to 10v
Peter_n_Margaret said
09:49 PM Apr 2, 2025
Measure the voltage AT the fridge.
Cheers,
Peter
TimTim said
03:14 PM Apr 3, 2025
Not necessarily your battery but very possible.
When last talking to a technician about my CFX55 he said that it draws about 15A on startup. I haven't tested whether that is the case but what could possible be happening is your battery may be dropping in voltage as the motor starts each cycle and it may not be starting. Or even running for a while and then cutting out. What colour are the lights on the fridge?
If you have a multi meter a good way to test your battery is to run something like a compressor and measure the battery terminal voltage and watch how it drops.
To test the fridge, you will have a cigarette plug lead so plug it in in a vehicle cigarette socket for a while and you should see the temperature drop after a while. If it doesn't you probably have a warranty issue.
DogBoyz said
05:28 PM Apr 4, 2025
i carried out this isolation test and the fridge went to -1 as i had set it. So the fridge is good.
My car battery went from 12.9 to around 10 as it drew power to run the fridge.
Im curious to know why my second battery shows 12.9 or 13, but will not power the fridge enough to drop it to -1 like my car battery did.
what is the actual problem going on with that?
Whenarewethere said
07:44 PM Apr 4, 2025
TimTim wrote:
Not necessarily your battery but very possible.
When last talking to a technician about my CFX55 he said that it draws about 15A on startup. I haven't tested whether that is the case...
I have the CFX28 (not made anymore). It is soft start, starts at about 2.7amps & gets to about 4.0amps.
I have done about 500 measurements with my Kyoritsu 2046 clamp meter & have never seen a spike. It is really smooth starting up. You couldn't ask for more.
The larger Waeco fridges, their compressor is only marginally larger than the 28 litre fridge compressor if you look in the manual.
The CFX55 probably is about 3.7amps at soft start then gets to about 5.5amps after about a minute like the 28 litres fridge does.
There is something else going on with the OP's setup. The system needs to sliced & divided to rule things out.
Check that the fridge runs on 230 volts.
Test it on a completely different 12 volt supply.
Measure the voltage at the fridge as well as the battery so you know the voltage drop. Which can be a lot even with so called good wiring. Just measuring voltage at the battery is wasting everyone's time.
Once they are ruled out then we can look for other problems.
TimTim said
09:21 AM Apr 5, 2025
Whenarewethere wrote:
TimTim wrote:
Not necessarily your battery but very possible.
When last talking to a technician about my CFX55 he said that it draws about 15A on startup. I haven't tested whether that is the case...
I have the CFX28 (not made anymore). It is soft start, starts at about 2.7amps & gets to about 4.0amps.
I have done about 500 measurements with my Kyoritsu 2046 clamp meter & have never seen a spike. It is really smooth starting up. You couldn't ask for more.
The larger Waeco fridges, their compressor is only marginally larger than the 28 litre fridge compressor if you look in the manual.
The CFX55 probably is about 3.7amps at soft start then gets to about 5.5amps after about a minute like the 28 litres fridge does.
Very interesting WAWT because as I said it was a Technician that told me and he was from the company that does Dometic warranty repairs. I had never tested mine to actually find out what the startup current draw is but a distinctive clunk as the motor starts has always led me to believe it was not a soft start motor.
I decided to test my CFX this morning with my inexpensive Digitech clamp meter and the current jumped to 14.69V on start up, so the technician was correct. Maybe they are putting cheaper motors in them now? Who knows!
I agree there could be a number of reasons why the fridge isn't working as it should but the first starting point is the battery, then the wiring and then the fridge itself. Unless the OP gets back to us we are just never going to know.
-- Edited by TimTim on Saturday 5th of April 2025 09:24:06 AM
If you want more accurate amps, & as long as you don't go over amp rating of the clamp meter.
You can loop one of the wires through the clamp meter, say 4 times, they divide that figure by 4. Great when you have to measure very low amps & the meter doesn't really go low enough.
TimTim said
10:52 AM Apr 5, 2025
yep... I know that but close enough in this case
TimTim said
10:26 AM Apr 6, 2025
DogBoyz wrote:
i carried out this isolation test and the fridge went to -1 as i had set it. So the fridge is good.
My car battery went from 12.9 to around 10 as it drew power to run the fridge.
Im curious to know why my second battery shows 12.9 or 13, but will not power the fridge enough to drop it to -1 like my car battery did.
what is the actual problem going on with that?
Sorry but I missed this post.
Well as you noted your fridge appears to be good so the problem is in all probability with the battery and the wiring but you have stated that it all worked before so I would suggest that it is the battery.
In your first post you stated
"at night or if i park under a tree fridge goes from 16 to 20 something.
It used to work really good. Nice cold drinks.
If the battery is 12.9 does that mean battery is good? If so, why does temp go up at night so much and battery falls to 10v"
that the battery runs down to 10.0V overnight or when camped under shade. If it is fully charged then is running down to that voltage overnight I would suggest it is your battery.
Just because a battery is showing 12.9V it does not mean it is good as it may still have lost capacity. That is why I suggested running something like an air compressor to see what happens. An example of this is I had a 120Ah AGM which displayed as fully charged but running my air compressor which drew I think about 50A it would only run for a few minutes. Whist I do have the equipment I didn't even bother running a capacity test.
What you may find is happening is the battery voltage terminal voltage drops overnight or when you are in shade. The fridge cuts out for a while. The terminal voltage rises again and the fridge either tries to start up of starts up for a short while until the battery terminal voltage drops again.
This isn't really going to help you but have you set your battery to the 10.1V cut off setting?
What model is your fridge so that we can look at the energy consumption and what size is your battery?
I'm guessing from what you have posted that your battery is close to your fridge.
Tim
TheHeaths said
11:19 AM Apr 6, 2025
How old is the big old battery in the black box?
I am just in the process of changing out batteries in my van as they showed 12.8 when charged, but dropped overnight to 12.2 with minimal light and tv use, and then just kept dropping to 8.5 after a couple of weeks. That said one was 12 years old and the other 11 years old.
The battery may just be old and starting its decline.
DogBoyz said
09:41 PM Apr 10, 2025
mine dropped from 12.9 to 10 overnight. So time for a new battery i guess.
I am frustrated to the bloody max with this stupid solar / car fridge bullcrap
My spare battery in back of my Kia Carnival (2006) is not lithium. Just a big old battery in a black box
But it was running my car fridge which is only 1 yr old. Dometic CFX
then one day it all changed.
I have a Victor MPPT controller. Anderson plugs and all that.
right now the dometic app says my battery is 12.9v
but my fridge is 16c when it is set to be -1c.
at night or if i park under a tree fridge goes from 16 to 20 something.
It used to work really good. Nice cold drinks.
If the battery is 12.9 does that mean battery is good? If so, why does temp go up at night so much and battery falls to 10v
Cheers,
Peter
Not necessarily your battery but very possible.
When last talking to a technician about my CFX55 he said that it draws about 15A on startup. I haven't tested whether that is the case but what could possible be happening is your battery may be dropping in voltage as the motor starts each cycle and it may not be starting. Or even running for a while and then cutting out. What colour are the lights on the fridge?
If you have a multi meter a good way to test your battery is to run something like a compressor and measure the battery terminal voltage and watch how it drops.
To test the fridge, you will have a cigarette plug lead so plug it in in a vehicle cigarette socket for a while and you should see the temperature drop after a while. If it doesn't you probably have a warranty issue.
i carried out this isolation test and the fridge went to -1 as i had set it. So the fridge is good.
My car battery went from 12.9 to around 10 as it drew power to run the fridge.
Im curious to know why my second battery shows 12.9 or 13, but will not power the fridge enough to drop it to -1 like my car battery did.
what is the actual problem going on with that?
I have the CFX28 (not made anymore). It is soft start, starts at about 2.7amps & gets to about 4.0amps.
I have done about 500 measurements with my Kyoritsu 2046 clamp meter & have never seen a spike. It is really smooth starting up. You couldn't ask for more.
The larger Waeco fridges, their compressor is only marginally larger than the 28 litre fridge compressor if you look in the manual.
The CFX55 probably is about 3.7amps at soft start then gets to about 5.5amps after about a minute like the 28 litres fridge does.
There is something else going on with the OP's setup. The system needs to sliced & divided to rule things out.
Check that the fridge runs on 230 volts.
Test it on a completely different 12 volt supply.
Measure the voltage at the fridge as well as the battery so you know the voltage drop. Which can be a lot even with so called good wiring. Just measuring voltage at the battery is wasting everyone's time.
Once they are ruled out then we can look for other problems.
Very interesting WAWT because as I said it was a Technician that told me and he was from the company that does Dometic warranty repairs. I had never tested mine to actually find out what the startup current draw is but a distinctive clunk as the motor starts has always led me to believe it was not a soft start motor.
I decided to test my CFX this morning with my inexpensive Digitech clamp meter and the current jumped to 14.69V on start up, so the technician was correct. Maybe they are putting cheaper motors in them now? Who knows!
I agree there could be a number of reasons why the fridge isn't working as it should but the first starting point is the battery, then the wiring and then the fridge itself. Unless the OP gets back to us we are just never going to know.
-- Edited by TimTim on Saturday 5th of April 2025 09:24:06 AM
If you want more accurate amps, & as long as you don't go over amp rating of the clamp meter.
You can loop one of the wires through the clamp meter, say 4 times, they divide that figure by 4. Great when you have to measure very low amps & the meter doesn't really go low enough.
yep... I know that but close enough in this case
Sorry but I missed this post.
Well as you noted your fridge appears to be good so the problem is in all probability with the battery and the wiring but you have stated that it all worked before so I would suggest that it is the battery.
In your first post you stated
"at night or if i park under a tree fridge goes from 16 to 20 something.
It used to work really good. Nice cold drinks.
If the battery is 12.9 does that mean battery is good? If so, why does temp go up at night so much and battery falls to 10v"
that the battery runs down to 10.0V overnight or when camped under shade. If it is fully charged then is running down to that voltage overnight I would suggest it is your battery.
Just because a battery is showing 12.9V it does not mean it is good as it may still have lost capacity. That is why I suggested running something like an air compressor to see what happens. An example of this is I had a 120Ah AGM which displayed as fully charged but running my air compressor which drew I think about 50A it would only run for a few minutes. Whist I do have the equipment I didn't even bother running a capacity test.
What you may find is happening is the battery voltage terminal voltage drops overnight or when you are in shade. The fridge cuts out for a while. The terminal voltage rises again and the fridge either tries to start up of starts up for a short while until the battery terminal voltage drops again.
This isn't really going to help you but have you set your battery to the 10.1V cut off setting?
What model is your fridge so that we can look at the energy consumption and what size is your battery?
I'm guessing from what you have posted that your battery is close to your fridge.
Tim
I am just in the process of changing out batteries in my van as they showed 12.8 when charged, but dropped overnight to 12.2 with minimal light and tv use, and then just kept dropping to 8.5 after a couple of weeks. That said one was 12 years old and the other 11 years old.
The battery may just be old and starting its decline.
thx for the advice