Should I wire my new 12V fridge directly to my house battery?

Johnynorthland · 10-09-2022, 03:05 PM

I’ve done it, I’ve ordered a 12 V fridge. I’m on my third rig with my third absorption refrigerator, we’ve had enough!.

My question is ;Should I wire my new 12V fridge directly to my house battery? I have 200 W of solar that I’ve never utilized, I do not have an inverter. And I have a 2019, Redhawk, 25R, class C motorhome with the original flooded house battery, (which I plan on upgrading to an AGM with more AH’s in the very near future). I have 2 rolls of 10 AWG that I plan on using.

I have read that running the refrigerators power supply back to the fuse box is inefficient because it goes through the converter/charger that’s built into my panel. With our camping style, We do very little boondocking, and I’m not looking to go Lithium at this time.

Either method would not be difficult to run the wires, and I would run an illuminated, on/off switch to the fridge from the battery with a 30 amp inline breaker, (if connected directly to the battery). I figure I can flip on the fridge only, the night before. And if necessary I could also plug in my solar generator through the house/shore power system and give it extra Amp hours, if need be. (But converter/charger would now be running)

Any advice or experience shared appreciated.

TaftCoach · 10-09-2022, 03:37 PM

Get a second opinion but since you will be on shore power most of the time why worry about the battery and go directly to the converter. All the protections are built in. I wouldn't worry about the small inefficiency when you will be plugged in most of the time.

Johnynorthland · 10-09-2022, 04:41 PM

Thanks taft, I keep going back & forth with this. On one had I’d like to do more boondocking, but if I did, I’d probably use my solar gen, and if I did then direct to battery won’t matter. I’m still undecided and looking for more input. But thanks again, your vote counts!

John

GHen · 10-09-2022, 05:02 PM

I agree also, go to the converter/fuse panel, not the battery. Best to have all your fuses in one location.

I also like having a full battery disconnect between the battery and any loads.

Johnynorthland · 10-09-2022, 05:09 PM

Thanks Ghen, that’s 2 votes for the panel! I don’t know what size line or fuse it back there yet, but there’s a slight chance I can use existing line, but I think I’d rather go with the 10ga wire no matter what’s there, unless it’s 10AWG/25 amps, but I doubt that very much. I will know after the 11th, once I pick in it up from the body shop. (My caps gelcoat started to peel had it repainted)!

Johnynorthland · 10-09-2022, 05:47 PM

Also what everyone’s opinion on keeping the refrigerator roof vent open, not sealing it off? I also have 2 roof fans up there on a temp switch, (for the old LP system) everyone seems to seal off the side vent, which makes sense to me.

Grumpy · 10-09-2022, 05:54 PM

Going to the fuse panel is the same as going directly to the battery. The converter charger supplements the battery as they function in tandem when on shore power. I don't know how it would be inefficient. I would not seal off the side vent as that is good access in case you need to service the fridge.

Johnynorthland · 10-09-2022, 05:58 PM

Sorry Grumpy,

I should have said less efficient, and it is, not my opinion just my findings. Just looking to go the best “rout”.

Thanks for your input, that’s 3 for the panel, it’s headed that way, keep’em coming!

billcf7 · 10-12-2022, 12:36 PM

You already have 12 volts going to old fridge and a fuse dedicated. Just use the existing circut. The vent i would close off but still have so you can get to back of fridge. I would get rid of fans.

Johnynorthland · 10-12-2022, 01:55 PM

Quote:

Originally Posted by billcf7

You already have 12 volts going to old fridge and a fuse dedicated. Just use the existing circut. The vent i would close off but still have so you can get to back of fridge. I would get rid of fans.

I was going to do that, but I pulled the existing fridge out today, it’s 15 amps but the wire should be 12 AWG but it’s 14. Manufacturer recomends 12 AWG as the smallest, so I have 10 AWG, so that’s what I’m using. Better to be safe. If the fridge starts to kill the battery and I’m not around to catch it, the amperage will go up as the voltage drops, why worry about that. I could install a low voltage cut off?

I’m sealing off the vent door by boxing the back in with plywood and filling it with spray foam, while still leaving the vent look intact and removable for service.

Thank you for your advice.

Johnynorthland · 10-12-2022, 08:48 PM

As I was going over my wire runs today, I pulled out my electrical panel to see the wires connected behind ir. There are pigtail wires Soldered to the board on the DC side, behind the fuses. These wires splice right into the wiring harness. I can’t find any gauge markings. The only numbers I found were “011” which written down on top of each other on these black wires, not written across like you normally see. Does any one know what these numbers are?

TomC_AZ · 10-17-2022, 07:54 PM

Are you able to take a picture and post that, might help identify what's going on there.

Also how close to the fridge is the converter/power center? I would still try and use the converter power source, but if you cant run new wire easily then do what is easiest. i.e. if running to the battery is easier than just do that. Just make sure to fuse or auto breaker it, and put that in a easily accessible location. :-)

Also as already mentioned, totally close up your old vents. They are not needed with the 12v and will actually let cold/hot air in, so just seal those puppy's up.

Johnynorthland · 10-17-2022, 08:04 PM

Quote:

Originally Posted by TomC_AZ

Are you able to take a picture and post that, might help identify what's going on there.

Also how close to the fridge is the converter/power center? I would still try and use the converter power source, but if you cant run new wire easily then do what is easiest. i.e. if running to the battery is easier than just do that. Just make sure to fuse or auto breaker it, and put that in a easily accessible location. :-)

Also as already mentioned, totally close up your old vents. They are not needed with the 12v and will actually let cold/hot air in, so just seal those puppy's up.

It’s already wired to my battery under my step, with a breaker, and a separate switch at my entrance. It was a lot easier then running the wire to my panel. Fridge is running great, and it’s huge compared to the old one!

For some reason I can no longer upload photos to this forum or IRV2? For the past year every time I attached a photo, I get to the last step to “close the window” and I can not.

Thanks for your recommendations

Johnynorthland · 10-17-2022, 08:40 PM

I’m also going to upgrade my battery from flooded to an AGM deep cycle. Now before everyone jumps all over me for going with AGM and not Lithium, please understand I only have and need one battery for my camping situation and usage and do not want the expense of upgrading my converter/charger, added with the extra cost of the lithium battery etc...

Having said all of the above I’m looking at the Vmax tank Group 31 and the Duracell Platinum Group 31, (available at Sam’s for $214). Does anyone have experience with any of these or can recommend any others. I can not fit 2 6V golf cart batteries because they are too tall to fit in my step.

Also, can anyone recommend a low voltage cutoff device, that I can just install at my battery location, that works as a standalone device?

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