Power for a Popup Camper

Hi,
My wife and I have a 1991 popup trailer that we occasionally use where there is no shore power available. Instead of using a lead acid battery, I was interested in building a reclaimed power cell to power our home away from home. Before tackling this project, I wanted to find out if anyone had done it, or if it was even worth the effort.

We would be running LED lights, 12v fans, and maybe a small dorm fridge using an inverter. We will be adding solar panels at a later date to top off the batteries, or charge them with an A/C charger when home.

Thanks and best regards
Shaun Walker

For ease of use, go with LifeP04 cells and not Li-ion. The Voltages match better for 12V applications. I am running my 5th Wheel on a 7s Li-ion setup and then buck converting that 23-29V down to 12V.

Now for inverting theis DC power it is better to run a higher voltage bank for the lower current draw. so there is also something to think about.

Personally If i was going to start over and I had nothing there are 2 things I would consider.

1) if 12V only and no Inverter in the system - totally go LifeP04
2) for Inverter usage Primarily and Some lights and minimal devices on 12V I would go 14s Li-ion or 16s LifeP04 (48V) and a buck converter for the 12V

Cheers

Yep, go for48V...
Li-ion and 12V just d'ont match

Hiya Shaun,

As the others have mentioned, there's a bunch of different ways to do what you're looking for. From your post, everything you'd be running would be 12v. The biggest challenge you have is the difference in voltage from what reclaimed 18650 Li-ion cells work best with and what 12v equipment works with.

3S (3x4.2v) is easy, but you lose a bunch of capacity when the voltage drops past 10.5v (about 50ish % of capacity), 4S or more is better and if you use a buck converter (about $20-50 for one that can run the fridge and everything else at the same time ~20A), you can get pretty much full capacity from the cells and run them a little lower voltage to keep them healthier.

If you don't plan to run AC power, don't need massive capacity and don't already have the equipment to test cells, I'd agree you may well be better going with something ready made (LifeP04 , AGM, etc). Money likely to be similar all done and it does take a hell of a long time..

It's fun though

There is no need for a 48V system as the currents will be very small anyway. LED lights, some fans and a fridge, I guess we're talking about 200W at most. 4s LiFePO would be beneficial as you could run the fans directly from the battery and the LEDs and fridge from an inverter. If you've built the LED lights yourself and can run them from a DC-DC converter you can run them straight from the battery as well. There are DC fridges as well and if you are willing to swap it out you could get away without an inverter and run everything from 12Vdc. With other lithium ion cells the same could be done with 7s 24V and a main buck converter for 24V to 12V conversion.

I live in a rig doing exactly what you are looking to do.

I run 3s in a 38' rig that I travel in full time with my wife and kids. I'm switching to 4s so I can use a higher percentage of the power in my setup. 3s works better for the 12 volt system, but 4s works better for the 110 volt system because it matches the inverter's voltage requirements better. Since we full time and like to boondock I'm more concerned about the 110 volt system running my refrigerator. Thus the change to a 4s system.

If I were starting over and didn't already have an expensive 12 volt pure sine wave inverter I would go 7s and get a 24 volt inverter. I've had better luck finding an affordable high amp 24 to 12 volt buck converter than an affordable high amp 12 volt boost/buck that would be needed to keep the 12 volt system running at around 13 volts.

It's definitely doable. I only run my AC off of shore power. I haven't been plugged in other than that in...a long time.