Tow vehicle to camper solar setup?

[MTR_Bumble]

I may be thinking ridiculous here and feel free to say so.

I am currently converting a short bus and plan to put 400w of panels and 200 ah lithium in it. We will also be pulling a camper behind it which we have yet to purchase. My question is, can I use the solar system on the bus to charge the batteries in the camper while connected? Would this even be effective or would it loose to much power over the distance? Thanks!

 

[chrisski]

You sure can. Just need bigger wires to compensate for the distance, and charging would be lower amps, more like 20 amps versus 100 amps, but voltage loss calculators will help you decide.

For my truck and my fifth wheel RV, that would not be practical, but a short is could be. Once you use the short bus for a while, you’ll start to gauge your excess power production. Basically, the sooner you’re done for the day charging the short bus leaves more room for the trailer batteries.

You may decide a separate system for the trailer would be good, even if its powered with portable panels.

 

[MTR_Bumble]

You sure can. Just need bigger wires to compensate for the distance, and charging would be lower amps, more like 20 amps versus 100 amps, but voltage loss calculators will help you decide.

For my truck and my fifth wheel RV, that would not be practical, but a short is could be. Once you use the short bus for a while, you’ll start to gauge your excess power production. Basically, the sooner you’re done for the day charging the short bus leaves more room for the trailer batteries.

You may decide a separate system for the trailer would be good, even if its powered with portable panels.

So maybe use like a manual switch? Once the bus batteries are topped off switch the current to the RV? Would the cost of the wiring even make it worth it? We want to do as much boondocking as we can, and trying to find a camper already solar equipped but most have them have a pretty sad setup from factory

 

[Short_Shot]

So maybe use like a manual switch? Once the bus batteries are topped off switch the current to the RV? Would the cost of the wiring even make it worth it? We want to do as much boondocking as we can, and trying to find a camper already solar equipped but most have them have a pretty sad setup from factory

If you're planning on leaving them hooked up at all/most times then I don't see why you would even need to switch back and forth.

The solar on the bus can just charge both, and your loads will share power from both. The only catch is you'll need to ensure the wires are large enough for your power needs.

If you disconnect, then there's nothing to worry about. Just unplug and drive away.


If for some reason you want to ensure the bus batteries are charged first even when hooked up you'll need some type of isolation switch, and depending on the load of the stuff you use it may need to have a fairly high current rating.

 

[chrisski]

So maybe use like a manual switch? Once the bus batteries are topped off switch the current to the RV? Would the cost of the wiring even make it worth it?

I would use a Victron Orion Tr Charger. This would let send the charge current back to the trailer battery to charge it. If the battery in the trailer was full and the battery from the short bus was empty, then the charger would prevent this onrush of current. Victron makes them in up to 30 amp models.

A switch would probably not be as good of a choice. My description of the short bus being done charging early just meant there was enough sun left in the day to charge both. IMO a DC to DC charger would be betterthan a switch for solar.

As to the cost in time and effort, that’s something to look at.

trying to find a camper already solar equipped but most have them have a pretty sad setup from factory

You can design a better system for you than any factory delivered model. The factory delivered models I’ve seen for a fifth wheel seem to be built for someone who is Boondocking with two batteries, which comes out to about 200 ah with perhaps 300 watts of panels tops. THere is a single set of wiring from the roof at 10 gauge.

That will be fine for most people, but running a propane blower fan with a 9 amp draw on a cold below freezing night when the heater is on most of the night, along with other things you do like watch TV and have lights on can drain more than 50% of the battery.

That’s why I think it could be better to design your own for the trailer also. In my case I put 600 watts of panel on my roof to start, 3S2P with two sets of 10 gauge wire To prevent voltage loss. If I’d had a factory set up, I would have needed to drill a hole through the roof to get an extra set of wiring for the next panel anyway. When I built mine, put a oversized conduit that supported the two runs of 10 AWG wire for 3S2P and was able to easily fit another run of 6 AWG wire for panels when I expanded.

Used solar panels off craigslist and a charge controller with wiring from the roof, may be a little more expensive, but could be worth it depending on the power requirements of this trailer.