Does fridge need battery power to operate?

**jesstravelsalot** · 02-14-2023, 08:45 AM

Does a 12v fridge (Dometic 4101) need to be connected to the battery even while using shore power?

Background: My fridge hadn't worked since December. It stopped working a day or so after an inspection/service visit. I recently realized that my battery disconnect switch was engaged (think this happened during said service visit), so the battery was full but not providing power to the trailer. The battery is now connected. I turned on the fridge and it works!

I read in a couple places that the fridge needs to be connected to the battery because the battery powers the control board, even when connected to shore power. These posts were mostly in reference to propane fridges. Mine is 12v. Do the same mechanics apply? The fridge stopped working right after the inspection visit so the timing seems to imply that was the issue. I am looking for any assurance that the fridge will actually work and that it's current state of operation is not a temporary fluke.

Thank you!

**Soundsailor** · 02-14-2023, 08:48 AM

Originally Posted by jesstravelsalot

Does a 12v fridge (Dometic 4101) need to be connected to the battery even while using shore power?

Background: My fridge hadn't worked since December. It stopped working a day or so after an inspection/service visit. I recently realized that my battery disconnect switch was engaged (think this happened during said service visit), so the battery was full but not providing power to the trailer. The battery is now connected. I turned on the fridge and it works!

I read in a couple places that the fridge needs to be connected to the battery because the battery powers the control board, even when connected to shore power. These posts were mostly in reference to propane fridges. Mine is 12v. Do the same mechanics apply? The fridge stopped working right after the inspection visit so the timing seems to imply that was the issue. I am looking for any assurance that the fridge will actually work and that it's current state of operation is not a temporary fluke.

Thank you!

Jess, I don't think so (don't need battery power). I suspect it was the battery switch that was the culprit. But I think one can run the frig from just shore power using the converter/charger as the power source.

**BeerBrewer** · 02-14-2023, 09:45 AM

I think that frig ONLY works on 12V DC. So when on shore power, it is powered via the AC to DC converter in your trailer.

So to your 12v fridge (Dometic 4101) needs to be connected to the DC power even while using shore power.

**DougW9876** · 02-14-2023, 09:53 AM

To give the simple answer, yes your fridge will work on shore power without a battery in most cases.

It is not a good way to do things as the battery is a part of the 12volt side of things and helps to keep the power flow nice and smooth. The battery switch normally disconnects the battery from the camper which includes the converter so the battery would not get any charge voltage with the disconnect switch in the disconnect position. The best way to use it is to have a good battery in place and the battery switch on even when connected to shore power.

**xrated** · 02-14-2023, 11:00 AM

Originally Posted by jesstravelsalot

Does a 12v fridge (Dometic 4101) need to be connected to the battery even while using shore power?

Background: My fridge hadn't worked since December. It stopped working a day or so after an inspection/service visit. I recently realized that my battery disconnect switch was engaged (think this happened during said service visit), so the battery was full but not providing power to the trailer. The battery is now connected. I turned on the fridge and it works!

I read in a couple places that the fridge needs to be connected to the battery because the battery powers the control board, even when connected to shore power. These posts were mostly in reference to propane fridges. Mine is 12v. Do the same mechanics apply? The fridge stopped working right after the inspection visit so the timing seems to imply that was the issue. I am looking for any assurance that the fridge will actually work and that it's current state of operation is not a temporary fluke.

Thank you!

OK, let's see if I can sort this out for you. A 12VDC fridge, or even an absorption fridge needs 12VDC to operate. Appliances like that (including the water heater) get the 12VDC from the battery, and in turn, the converter/charger charges the battery if you are plugged into shore power....or running a generator for the trailer. If you are not plugged into shore power or do not have the generator running, the 12VDC fridge will require battery power. Same thing with the absorption fridges, when running on propane....they still need 12VDC from somewhere....the battery if you're not plugged in or running a genny. And even an absorption fridge that is running on 120VAC instead of propane, will require 12VDC in order to operate. The same thing is true with your water heater...if running on propane, it still needs 12V to operate. If you are plugged into shore power and the water heater is operating on electric and not on propane, you still need 12VDC for it to operate

You may be asking why....each of these items needs 12VDC to operate, and that's a good question, especially if you are plugged into 120VAC from the shore power. The reason is that the control boards of all types of fridges run on 12VDC.....same with the water heater, whether it's on propane or 120VAC...the control board requires 12VDC in order to function. A microwave is strictly 120VAC though, and you don't need to have 12VDC for it to operate. Hope this helps a little.