How long does your battery last, without charging, while running a fridge?

Running the fridge of the truck battery and just charging the battery by running the truck is a bad idea.

Say the fridge draws 100 amps. Say the battery is 100 amp hour. Simple math, fridge runs for an hour.

Lets say the alternator is 100 amp. Magically start the engine and the alt puts out 100 amps. Simple math says the battery will be recharged in 1 hour.

But that's not how a lead-acid battery recharges. It may be able to charge at 100 amps at first, but then the amps start to drop. It will take 12 to 24 hours to recharge the battery. Unless you are constantly making road trips you can forget about ever totally charging the battery.

Granted, the fridge does not pull 100 amps. But you will be constantly replacing batteries, even good ones.

Either find another way to power the fridge or put the truck on a battery charger every night.

 

You are right. Sometimes I have to do this stuff from memory. Thought it was 9.7 but it’s 13 amps which I realize is a big difference.

 

How does a dual battery system get around this?

 

What about dc - dc chargers?

 

A Dual battery system does not get around the problem. It does have it some nice features though. With a dual battery system once the "house" or in your case "fridge" battery is dead, your starting battery is still charged. Starting the engine is no longer magic, it will start right up.

But the "house" battery or "fridge" battery will still take a long time to re-charge. There are some solutions that can help. Large stereo people and large boat people sometimes run 2 alternators. A higher power alternator can help. But lead acid batteries no matter what take a long time to "top-off" the charge. It will only take a few amps, but for hours on end.

There are also batteries with different chemistries other than lead-acid. I know a lot less about them. Most people choose lead acid because there fairly cheap and very available.

 

Do PWM solar controllers have the proper charge cycles for AGM batteries? I just have the Wanderer controller...

https://www.renogy.com/renogy-wanderer-li-30a-pwm-charge-controller/

 

In my previous setup i had the new dometic plb-40 battery has built in dc/dc charger, solar charger, wall charger and would run my 63 qt for a couple days. Anytime i drove it charged back up off the dc current from the truck. I liked the added insurance my truck would start if i was way out alone...

That said if you don’t want to add the cost of something like the plb-40 I’d replace your regular battery with a deep cycle (i have a 27F northstar) deep cycles don’t get damaged by draining down farther like traditional starting batteries.

Finally i saw it mentioned but the ARB, and most other fridges, have low voltage cut offs. Though I’d carry a jump pack just in case. Last thought you can probably just unplug your fridge at night when you aren’t moving and the sun is down. Mine never raised much more than a few degrees with this method either providing its full (mine has thermal cover also) lotta options.

I’ll echo a few others. DC fridge is my favorite truck upgrade!!

 

Yep, I have a 27M X2 Power AGM.

That plb40 looks nice, but I’d rather just throw in another battery. The less I have to load and unload the better.

I think what I’m ultimately taking away from this is that if I really want to ditch the propane, I’m going to need a more efficient fridge and/or a second battery.

 

OT a little but some motorcycles are starting to have 2 charginging systems. My Kawi Nomad is one with 2 alts and 2 rec regulators and 18 diodes in the system. 44 MAX amp output which is fairly large for bikes. It's still brushless.

 

Keep in mind the PLB is 14lbs.... with all the chargers built in. If you did a traditional dual battery you’d spend as much or prob quite a bit more, it’d weigh 60-70lbs and you couldn’t take it out and use it in a different car for a family vacation or road trip... just my thoughts. New battery tech is light years ahead of traditional AGM, or lead acids.

 

As an experienced RVer I can assure you that the 3 way absorption refers are designed to run on 12v only when the truck is running. The 3-way in my current RV automatically switches from 12v to propane as soon as I stop driving and turn the engine off.

Getting a compressor fridge that is designed to run on 12v is step one. Aux. battery, solar, solar generator, are separate secondary decisions.

 

That’s good to know. I don’t believe mine is automated, which is no big deal but it does mean I’d put a low voltage cut off on sooner rather than later.

Do have a recommended source for everyone parts? I see there’s a bunch out there...

 

I know it's off topic but the personal debate to add another 60lbs of battery to my truck or worry about killing it somewhere makes it really hard to want to drop $600 to replace two very nice coolers I already have. I get the purpose of a fridge but I have zero desire to buy one until I get a trailer with a proper battery setup.

 

I’d use the coolers. They make sense to me. The top selling point for the Toyota pickup on deep off road adventures is that it will get you out and get you home, or at least has the highest chance of getting you home. We have all seen the “truck won’t start after installing LED’s” threads. Now a person wants to rethink the entire charging system? For a fridge? Hard pass. When you’re deep in the woods with your refrigerators, Murphy’s law has posted up in a lawn chair with a nice cold one...waiting. Because a person wanted to skip the ice and be a tech nerd. If you’re out long enough to need a fridge, you should be harvesting your food. Otherwise, a cooler or coolers is the wise decision.

When I say things like this, people typically respond with “people have added so and so with good results”...and that’s fine. For me, the risk vs reward in a situation that has a small margin of error, like say a Death Valley trip, id rather re think what I should bring for food.

Speaking from personal experience not related to fridges. Like. I didn’t start cracking weldments or breaking components until after I went long travel on my 1st gen. It was more fun, scored me cool points, but I would never go out alone with that truck. I added too many risk factors that the parent vehicle wasn’t designed for.

 

Valid. And I have no quarrel with any of that.

But...I think that in these super sensitive electrical systems, changing out factory electrical components for others (like the mentioned LED tail lights) is quite different than adding an entirely new circuit. That is, no splicing into existing factory circuits/add-a-fuse bs. I mean, the battery isn’t smart enough (yet) to pass anything but voltage info along to the brain, whereas swapping out a tail lamp for another with radically different resistance properties is quite a different thing in that the computer probably thinks there’s a short somewhere and shuts down power to avoid a fire.

Honestly I have no idea what I’m talking about but maybe I’m right.

 

Sure. It’s one thing to have a thing bounce signals/voltage through and ecu and another thing when you’re adding bus bars and hardware. I agree. My perspective is probably in the minority, and that’s that I like to eliminate instead of add any complications, whatever they may be. I feel like thats why they don’t have PlayStations in the space shuttles. One less thing to catch fire in a high risk environment

 

That’s the primary reason why I was looking into older LCs before I went with my Tacoma: fewer features. I wanted decent safety tech ie ABS and some kind of airbags. But in the end the high mileage and in what ways those miles were clocked could alone be a “feature” awaiting to reveal it’s vulnerabilities once Murphy puts on his beer helmet.

All in all, I’d rather just have a palomino and ~1,000 + acres in Wyoming or Utah.

Until then...

 

What year palomino? Once you start adding aftermarket saddles it becomes a headache. Don’t even get me started on liver failure. Heart failure. Bad knees. SO Many weak links.

 

Yeah and the horse will likely have some issues too.

Fuck it. I’m going to Mongolia.