Off grid upgrade help

[ScottyP]

Hey everyone. I just bought a ‘87 slide in camber that is wired for shore power only and I am in the process of buying what I need to rewire it to for off grid power.

I’ve already bought:

RecPro 35 amp charger

Olteanp 2200 watt inverter


And I plan to buy:

Go power ts30 30 amp automatic transfer switch

And

(2) 100 ah lithium deep cycle batteries.

I’m a novice at electrical work and have been trying to make sense of all the wiring diagrams folks have posted but with my particular components I want to make sure I have the basic diagram correct.

First pic is my sketch and the second two were on the website for the automatic transfer switch.

Any input would be appreciated.

Thanks,
Scott

[JohnB]

Hi ScottyP,

Welcome!

A few comments on your wiring sketch and your off-grid approach to camping. I cannot read the transfer switch diagrams; the lettering is too small, so I can't comment on them.

I see you included fuses between the battery, the inverter, and the converter/charger. Good for you.

It's crucial to add a fuse to protect the camper's DC fuse board and wire. Without this, there's a risk of overpowering the wire and potential short circuits. Remember, that small wire is connected to 200 amps of power. If that wire shorts to the ground, it essentially becomes a fuse until it melts apart.

The same fusing comment applies to connecting the truck battery.

I have seen some of my friends' big solar setups on their campers, and they sell bolt-on lug fuses to deal with this high-power battery setup. Feeding small wires off a large supply is not new; you need to realize how to do it.

You need to check with your battery manufacturer to see if your truck's alternator system can charge that brand of battery directly. The truck system is set up for lead-acid batteries. Some lithium batteries are OK with it, and some are not. They may need a DC-to-DC battery charger or other Battery Isolation Manager.

Consider adding a 200 amp plus disconnect switch after the batteries to unhook that 200-amp supply when necessary or for safety to work on the system. If you have an LP alarm or other devices that are on all the time in your camper, radio display, etc., during storage, you need to disconnect the battery power, or those never-shut-off items will drain your batteries over time. You can unhook the negative battery cable like the older campers have to, but that can get old quickly.

Since you picked such a large inverter, what do you plan on powering with it?

And what are your thoughts on how to recharge the batteries when you are off-grid? With only a 35-amp converter, if you ever drain the two batteries down to, say, 20% state of charge, meaning there are only 40 amps left in the batteries, to recharge now 160 amps of battery can take at least 4.5 hours at a 35-amp rate. That was done without using DC in the camper to run other items simultaneously.

I am not the guru on off-grid camping, but we do boondock a fair amount. We just completed 30 days off the grid using our 2, group 27 lead acid batteries and a generator 4 hours a day to recharge them back to at least 80 to 90% state of charge. We can go about 4 days with no recharge if we have to, but we are also limited where we camp on generator run time. We do not have an inverter, and we like to camp under trees, making it hard to rely totally on solar. We have been doing this for the last 18 years. Granted, we cannot run the air conditioner, but we can deal without it where we camp.

We all camp differently, and that is OK. All you need to do is be happy with how you go camping.

I hope this helps,

John