Trailer camper charging setup.

[Knowshowrosegrows]

I have a Toyota Highlander that I’ve rigged as a solo camper. It has a 206 lithium battery, 20 amp dc to dc charger and an inverter. I just bought a light tiny enclosed trailer to tow. It will have a 12v fridge in it, so it will need a battery onboard. I want to park the camper and then drive around during the day and sight see. The trouble I have is that the dc to dc charger and battery will be moved to the camper, so when I drive all those miles during the day, I won’t be recharging my battery!

Should I leave my charger and battery in the car and then put a second battery in the camper. When I come back to camp is there a way to connect my car lithium to that camper lithium and use that power I just created?

 

[Supervstech]

Maybe.
Keep in mind, connecting a fully charged lithium battery to a nearly dead lithium battery can cause melted wires and arcs on the connections.

 

[MisterSandals]

is there a way to connect my car lithium to that camper lithium and use that power I just created?

How about using the DC to DC charger to charge from car lithium to camper lithium?

 

[Knowshowrosegrows]

How about using the DC to DC charger to charge from car lithium to camper lithium?

I think a dc to dc requires >14v to start charging.

 

[wme]

Trailer gets Lifepo4 battery and a solar panel

 

[Knowshowrosegrows]

I’ve got it! I keep the inverter, battery and dc to dc charger in the car. I put a second battery, an ac to dc charger and a shore power plug on the outside of the trailer. After driving around producing all that free juice, I run an extension cord from my car inverter to the shore power plug and run that through the ac to dc charger thereby charging my camper battery for free!

I lose juice in all the inversion/conversion but it’s juice that would be lost anyway.

 

[HRTKD]

Deploy one or two solar panels on the ground, outside of the trailer. When I need more charging power, that's what I do.

 

[0truck0]

Well, #1, you came to a solar forum, so the obvious is to just put solar on the trailer and be done with it. 200 watts might be enough. WIth this you may never need the vehicle to charge.
#2, electricity is not free when driving. You will be using the alternator to charge which means taxing it more-so to charge another battery, so you pay in gasoline. The alternator only puts out what is needed, and that means if none is needed then the car is not encountering resistance from spinning the alternator - and if little is needed then the resistance is little - and if a lot of juice is needed then there is a lot of resistance. I think it is typically about 6 hp at full output, but different on all.
You probably have enough room on the roof for at least 400 watts of solar, so I would suggest going big on solar panels from the start.

 

[justinm001]

Why have batteries in the trailer at all? Leave it all in the car and disconnect the trailer when you leave. Then it'll charge up.

If you're gone a few hours the fridge will be fine. If gone all day it'll still be OK. Toss a $30 temp sensor with logging and you'll be sure.

Another option is to use some 12v ups battery backup. Or some auto transfer switch that'll use trailer battery when disconnected from car otherwise it'll use the car. You'll need to manually charge that battery separately but shouldn't be using much power. Perfect for a little 12v solar panel with built in controller.

 

[HarryN]

The easiest way is to have an aux battery in the trailer and an aux battery in the vehicle.

As you noted, have solar in the trailer to help supplement that load. 400 watts is a good target to support a fridge.

For moving power from the vehicle to the trailer, use an inverter in the vehicle to convert to 120 vac and a small charger in the trailer.

 

[DrObbins]

Put a Jackery 500 in the trailer and plug the fridge into it. It can run 24hours on it easily. Then you can recharge the Jackery by solar or your car battery when needed.

 

[Aussieguy]

while you are out driving ... trailer will be using minimal power
a couple of good solar panels will charge it
if you have a lot of shade you could deploy a ground panel as well

Have enough battery capacity to last around 2 or 3 days just-in-case weatherperson does not like you
Would be nice to capture all them pesky alternator electrons... but the time , effort and expense would be better utilized in other areas.
The last thing you want to be doing after a hard day's sightseeing is playing around with batteries

 

[justinm001]

The last thing you want to be doing after a hard day's sightseeing is playing around with batteries

This!! You want a system that works for you not one you have to constantly work for

 

[Vigo]

Unless it is in the shade, any trailer big enough to put a fridge in is big enough to install enough solar to cover the fridge use. I would actually put a little effort into keeping the trailer interior cool with a small fan to help convection flow.. your fridge may become a lot more of an electrical consumer if it is inside a 120f space. It may be cheaper to encourage enough flow to cool the trailer interior vs making enough electricity to compensare for all the additional compressor runtime.

 

[Tomthumb62]

Unless it is in the shade, any trailer big enough to put a fridge in is big enough to install enough solar to cover the fridge use. I would actually put a little effort into keeping the trailer interior cool with a small fan to help convection flow.. your fridge may become a lot more of an electrical consumer if it is inside a 120f space. It may be cheaper to encourage enough flow to cool the trailer interior vs making enough electricity to compensare for all the additional compressor runtime.

We just went through the effort to install insulation in our trailer. Previously had almost zero insulation. Still none in the roof (can’t due to aesthetics), but hoping this summer it will stay a bit cooler in there and help the fridge run less.