Camper Batteries with fridge on DC while towing

Just got a spiffy new Casita camper this week! The taco snatched it 3 hours from Rice like it was nothing! You know its there but its not struggling. I was concerned with the power output but it did perfectly fine in Sport 4 and 5 with ECT getting 16MPG on relatively flat and slight rolling hill mix going 60-65. The camper is just under 2500 lbs dry.

Anyhow, my question is does anyone have any experience running a camper fridge on DC with their 3rd gen taco (with towing package of course). Im just wondering if the factory setup will provide enough amps to keep the camper deep cycle battery full while running my 4 cu ft Dometic on DC?

Im going to do some tests this weekend with a 1 hour trip and see. Just wondered if anyone else here had any real world 3rd gen experience.

 

Bump, I'm curious about this as well.

I have a dual battery setup in my taco and it charges both just fine but I also want to add another battery to my teardrop I'm building and think three would be too much.

You will be fine, I probably won't have enough juice.

 

@LeftCoastNerd has a Casita and was asking about this very issue awhile back

 

How long is a piece of string?

Can't tell you anything without knowing the average hourly current draw of your fridge, all your other electrical accessories, and the output of your alternator (stock?).

If your camper's battery is hooked up to your alternator, and you start with a charged battery, I highly doubt you will ever see a dead battery while driving. Parked is another story. That said, the stock alternators are what, 130amp or so? There's definitely room for upgrades.

Keeping your fridge full (or close to full) will improve its efficiency. Pre-chilling (or freezing) foods at home prior to putting them into the fridge will help, too.

 

Battery capacity is rarely the limiting factor. Anywhere from 70-100ah is plenty. Can your capacity get all your electronics through ~48 hours without being charged? If yes, you've got enough. The trick is keeping them charged.

I'd rather have a 70ah house battery with a 100W solar setup than 140ah house battery array without solar.

 

my conclusions were that the DC mode is basically useless. I run the fridge on propane when traveling, and AC when I have access to it. to get DC fridge to work, you'd need to upgrade the Tacoma power wiring to the 7-blade connector, AND upgrade the Casita wiring from the trailer plug through the rats nest of scotchlocks thats under the cloest to the main power panel. I measured voltage drops, and about 50% of the drop was on the Tacoma side, the other 50% was between the trailer plug and the main power/fuse panel on the Casita, the net aggregate is, your DC fridge will draw down the Casita battery while driving.

 

I'm thinking solar on the teardrop will be the way to go. The alternator will take care of my truck dual battery system and the solar will run the teardrop.

As for the OP question, the truck will charge his house battery while he is driving but will obviously do nothing to maintain the charge while in camp if he doesn't run the truck engine.

 

Oh, if it's not a direct hookup to the truck's electrical and there are a bunch of wiring limitations, then +1, forget that noise.

 

Interesting. Good to know.

 

if your Taco has the factory tow option, its got a rather beefy alternator, it should be able to charge the trailer battery just fine, as your dual tacoma batteries will likely already be fully charged. even when I was trying to run my fridge on DC, my tacoma battery was still 14.1V, even tho the trailer power system was dropping to 12.5V and sinking... my issue was purely the 12 or 15 amps that the DC fridge draws

 

Thanks for the replies!

Battery was at 12.36v when I left my house yesterday. When i got to my destination 1 hour later it was 12.84v. This was with the fridge on propane. So I know that the truck will at least charge the battery.

My battery was not topped off when I left bc needed to run the furnace to burn the shipping oil out of it a couple days ago. I purposely wanted to let the battery not full to see if the truck would at least charge the camper battery.

I'm not sure if a 1 hour trip home will be a good test with the battery on D.C. But I'm going to try tomorrow. I'll measure the voltage when I leave and when I get home just to see what happens.

 

go solar.
You can get panels pretty cheap now days.

 

I thought about going solar and decided against it. If your bondocking solar is hard to beat for quiet power but if you have to carry a generator to run high power appliances i wouldn't bother. You can run the fridge on propane and the trailer battery will be charged while you drive. The generator gets pulled out if the AC is required. I have an inverter that will run my 120V "stuff" from the charged trailer battery.

 

The limiting factor in this situation is almost always the wire size between your alternator and your 7-pin trailer connector. I don't what gauge it is in the 3rd gens, but I'm sure it's not enough to keep up with the draw if the fridge. The 3-way dometics draw a lot of juice on DC mode. You'll end up draining the trailer battery over time.

 

the power from the truck while driving is to keep the battery charged.it won't run the fridge.i run the propane while driving to have the fridge going.truck power supply won't do it.

 

I'm just going to roll with a generator.. Cabelas had 3500 watt champion inverter generator with remote start for $200 off so I snatched it up.. had great reviews and good videos on YouTube.. I wanted the 3500 so I could run even a microwave with my small roof ac.. its extra quiet also.

 

The fridge in my camper doesn't even offer the DC option (built in 2012). I think newer campers don't have the DC because it's kind of pointless. The fridge works better on propane or AC.

 

in THEORY, the 130A alternator in my Tacoma (factory tow option) should EASILY handle the fridge. but in practice, as I said, there's too much voltage drop in the wiring and harness connectors. even with my fridge on DC, and headlights and stuff on in the truck, I still see 14.1V at the trucks battery, but 12.x at the Casita's camper battery. switch off that DC fridge, and boom, 13.8V or so at the trailer battery, charges it right up. With the fridge on, I measured about 13.5V at the tacoma side of the trailer socket, suggesting about half the drop was in the trucks wiring, but that the other half was in the Casita.

lets assume its a 1.5V drop at 15A or so for the fridge, that implies there's 0.1 ohms resistance in the combined wiring.

Casita specific: the trailer plug is connected under the closet using a pile of scotch-locks. some casita owners have redone that using a terminal strip and ring connectors, and gotten more tow vehicle voltage to the Casita's system, quite possibly enough to keep the fridge happy on DC.

 

Why woild you go to all that trouble rewiring when you could just turn on the propane?

 

I would prefer not to have the propane on while driving, its a safety thing.... you're supposed to shut it off at the tanks before entering a gas station, for instance, and a typical road trip with my camper involves 1-3 gas stops in a day.