DC operation of fridge

[Saskhunter]

I am new to RVs and notice while driving my truck does not charge my Northern Lite truck camper battery. Is this normal? Within 4 hours the fridge kills my RV deep cycle Battery.
Is it ok to travel using the gas for the fridge?

[Kayteg1]

When you say "I live in a trailer" the following question usually is
"single, or double wide?"
When you say "I live in a camper" the following question often is
"do you have engine in the rear, or front?"

[burningman]

Saskhunter wrote:
Thanks to everyone, I have learned a lot about my trailer today.

Next lesson, you don’t have a trailer, you have a truck camper 🙂

[otrfun]

Saskhunter wrote:
I am new to RVs and notice while driving my truck does not charge my Northern Lite truck camper battery. Is this normal? Within 4 hours the fridge kills my RV deep cycle Battery . . .

I assume you were running your fridge on DC (including the boiler) with one battery? If that's the case, your fridge was probably drawing ~20 amps of 12 vdc plus any current being used to power anything else you may have had on in your camper while driving. The wiring on many trucks are only capable of supplying 8-10 amps of current to the 7-pin connector on the camper. That leaves you with a 10+ amp deficit. That's enough current drain to run one 12 vdc 24/27 battery down to 50% in approx. 3-5 hours. Bottom line, your truck was very likely supplying 8-10 amps of current to your camper. However, that wasn't enough current to keep up with the ~20 amps the fridge was using---thus a discharged battery in ~4 hours.

[ajriding]

Agree, never run it on DC (unless you have huge ample power from solar, then only in sun where there is more than enough power to run fridge and have power left over for charging).

I think fridges have 12 volt DC just as a sales gimmick.

Yes, solar. Get at least 200 watts, better to go 300 watts up there if you have at least two batteries. Don't start with 100 as you will end up wanting more, and it is just easier to do it all at once. Then you get a MPPT solar charge controller which will do a much better job charging and maintaining your coach batteries than the alternator ever could. I almost never charge from the truck ( I have a switch to control that).

I also ran a completely separate trailer 12v charge system, so bypassed the truck fusebox and small wiring. I used heavy gauge wire with the shortest possible run, so the trailer gets the most amps possible. But, I never use it since the solar is so effective.

I used to run propane while driving. Yes, some danger. If you make short drives, under 3 hours, maybe 4 (experiment with the time) then just turn fridge off and then back on when you park. Fridge will keep cold for a few hours depending on temps.

New fridges are compressor models using "Danfoss" compressor that will run on the DC power and use much less power than the power hog DC element in your 3-way fridge. It will probably use less amps than your inverter draws by just being on. Paired with 200-300 watts solar and a pair of true deep cycle batteries this is a good set-up.

[Paradox123]

Because I have solar panels, I run the fridge on DC while traveling in daylight with no problems. Saves having to turn the propane off and back on for fueling and saves propane.

[BradW]

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29896781.cfm

[Grit_dog]

Absolutely use LP mode whenever AC is not available unless you have a very robust battery and charging setup.
As you found, fridge draws enough juice to kill a normal single 12V battery pretty quick.
There is no issue running it on LP while driving (contrary to some who may reply to this thread). Be aware, certain conditions, speed, wind etc can extinguish the LP flame though and you may think the fridge is on LP and it switched to DC without you knowing.

Some campers are better than others about keeping the flame lit. Our old AF is good at highway speeds up to around 75mph if there's not much wind. If it gets very windy, it goes out.

[Saskhunter]

Thanks to everyone, I have learned a lot about my trailer today.

[DWeikert]

Not sure if your 2015 looks the same, but here's a quick video about hooking up the +12v wire and fuse to the trailer harness. This wire is not connected from the factory.

Youtube Silverado trailer power wiring.

Keep in mind that this will keep +12v on the trailer harness at all times, even with the key off, so you could end up discharging the truck battery while using the camper. The solution there is to isolate this 12v with a isolation solenoid that only activates with the switch on.

Even after hooking this up the wiring probably isn't large enough to charge the camper battery while also supplying power for the DC fridge. The more current flowing through the wire, the less voltage will be at the camper's battery. With no other (major) loads the wire is sufficient since as the battery gets closer to full charge the current through the wire will decrease and the voltage at the battery will increase. If there's another load drawing significant current you'll never get full voltage to the battery.

Solar will definitely help since it will be charging the battery all the time, not just when the truck is running. Assuming your solar is putting out enough to power whatever loads you have and still have enough left to charge the battery.

[enblethen]

Chevs in most cases need to have charge line terminated in the under hood fuse/relay box. Driver's side fender well. Check owner's manual. Chev also on some puts a dummy fuse in the location for charge line.
Note that if you have a three way refer, the 12 volt system for the element will discharge the battery fairly rapidly.

[Kayteg1]

The charge wire, even it usually is #10 size goes several loops before reaching camper battery, so the wire resistance plays the role.
We do have tens of topics how members who want better charging - run heavier wires either using Lance plug, or HD designated plugs.
Also beware that 12V fridge elements usually have much lower output, than 120V or propane outputs, so even when you solve the charging issue, the fridge will not perform the best with this option.

[Photomike]

Check the voltage at the camper battery when the truck is off, then start the truck and check. If the voltage goes up you are charging. If not then you are not. (Don't plug in 110 for this test).

On my truck it needed a fuse so that the circuit became live. $2 and I had a pack of them.

Never run the fridge on 12V for any length of time. I would use 110 to cool it off at home, switch to propane when I pulled out of the driveway and off propane when I got back in the driveway from the trip. Most campgrounds I stayed at did not have power. Yes off when refueling as well.

[Saskhunter]

My Truck is a 2015 Chev duramax Diesel 2500.
I have a 7 pin cord I believe.
I will check my fuse box on the truck for sure.
Will adding a solar panel really help with the on board battery charge?
We just returned for a first trip with the camper and put on over 7,000 kms. Included Saskatchewan,Alberta,British Columbia,Yukon and Alaska. We loved the camper and am excited to go on another trip.
Thanks to all for you help

[work2much]

Your truck may be charging the camper but the discharge rate from the fridge will be higher than the alternator charging so it may seem as though your truck is not charging when it is.

Try running the fridge on gas next trip and see if you get a charge. The charge through the 7 pin harness is a small trickle charge so don't expect a short drive to result in a big difference.