diy solar

diy solar

Travel Trailer Power Setup

Helping a friend put solar on his new 16' travel trailer. His came with a single deep cycle lead acid battery on the trailer tongue used for the house power, and wired into the break away switch for the electric brakes. His didn't have a tiny frame battery like my flatbed car hauler has. We plan on replacing it with 2 100ah lithiums in parallel, and we will install a small battery on the frame for the break away electric brakes the trailer brake will trickle charge it. I find my car hauler the battery doesn't last long I just replace it before I use it since it sits most of the time.

We don't want the truck 7 wire charging the lithium batteries. We installed a Victron blue smart charger if he needs to use shore power to charge. We fabricated a nice box for a honda inverter generator in the back of his pickup to secure the generator. Mostly boondocking and camping in cool climates won't need the AC much likely it might only be used for the microwave. He have a small inverter for a small TV, or items needs. I think with 600 watts of solar and 200 AH of lithium power should be more than enough. We did some testing with a single 100 ah cheap $270 LifeP04 I got on eBay for experimenting with solar on a shed in my backyard it was way better than the interstate Deep cycle they gave him. I'm only concerned is about the lithiums being able to handle cold weather in a box on the trailer tongue. He is going with Battle Born they say go down to -4 up to 135F we could go with the heated versions. Maybe we put some insulation in a box up there.
I use my lithium house battery to run my breakaway switch. The breakaway system uses no power unless activated and I have the added comfort of knowing that if my house batteries are working my breakaway system will work as well. Keeping the batteries warm will greatly improve their performance. Keeping the batteries cool will extend their life. I put mine inside for better temperature control and it’s also much harder to steal.
 
Yea, I can see that for 9000BTU. Our trailer is only 100sq ft (7 x 14) with no windows and R5 and it seems pretty well matched.

We do an optional double-tarp (18mil thick) extension on the tailgate for an additional 36sq ft room. There's a door between the trailer core and the tailgate extension. Obviously the tailgate extension doesn't have any insulation but with a small USB fan to push air to it from the core - the Senville just barely worked down to 26F to keep 75F in the core and 60F in the extension. Just the core is no problem w/heat.

Of course - the heat rises to the upper half of the trailer so we use wool socks / slippers to avoid the cold floor as I'm not sure how to force heat down without fans or something that will take up room. You can literally put your hand near the floor and it's 65F? and raise it up to 75F at 4ft off the floor and feel the temp change. :)
When I rebuilt our travel trailer (old and heavy water damage) I wanted to make it viable to be comfortable and have a functional water system at -30 Fahrenheit. I installed 300’ of radiant pex tubing in the floor and connected an egr cooler to the exhaust of each of the 2 diesel heaters we use for heat. The amount of heat put into the floor is enough to keep the tanks from freezing and to keep the floor comfortable. I was able to maintain a 65 degree inside temperature at -31 and had a nice 80 degree or so floor
 
If we make it (road conditions), we're taking our 1st trip in the trailer to the central Oregon high dessert next week. The forecast is 11F - 22F lows.
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We have electric heaters (and a heat-buddy on a 30lb tank) as backups but it will be fun to see just how far we can push the mini-split. The specs say down to 5F... but there's no substitute for actual tests. :)
 
I am using a growatt 3000 24v, 280ah 24v lifepo battery, runs AC (I do have soft start) no issues.
I am adding solar assistant and a 7 inch screen so I can see status...
the growatt draws 13 amp (adjustable) during battery charger at 60 amps 24v.
 
I am using a growatt 3000 24v, 280ah 24v lifepo battery, runs AC (I do have soft start) no issues.
I am adding solar assistant and a 7 inch screen so I can see status...
the growatt draws 13 amp (adjustable) during battery charger at 60 amps 24v.
so is even possible to reach the advertised 2w draw level during solar charge only?
 
Hello again,
So I got the inverter and battery delivered. And now I am trying to figure out fuses and wire sizes.

I ended up with the Eg4-ll v2 battery. Since it has a the built in DC circuit breaker, do I still need a t class fuse on the main positive battery cable? I've read it both ways on this forum, it seems a lot of people suggest a t class is still necessary for a 48v system.

The other question is where else fuses should go.
1. If I put a 125a t class fuse before my main positive bus bar, and use the same size wire (1awg)to go from the bus bar to the inverter, then I don't need another fuse between the bus bar and inverter right?
2. I will also have another positive lead from the positive bus bar to a 48v to 12v 20amp converter using a much smaller wire, I assume this means I now need a smaller fuse for this wire as well. Problem is I can't find 48v fuses that small. If my math is right, the 48v converter will only draw <5.5amps at 48v, that means I would need a fuse and wire rated for about 7amps at 48v to supply the converter. Problem is I can only find fuses that go down to 30a and are rated for 48v systems. I did find a 10amp DC rated breaker, is it okay to use a breaker instead of a fuse in this application? Are the 12v automotive blade fuses okay to use with 48v systems?

Im really lost with all the different fuses to use and I want to make sure my setup is safe. I welcome any suggestions. I am also working on a wiring diagram for my intended setup that will hopefully make this more clear.

Edit:
Forgot to include the wire size portion. I plan to use 1AWG battery cables since that is what the victron manual recommends.
I will also use a smaller wire to feed the 12v converter that I'm still researching.
Lug size is the biggest thing I'm struggling with, I am planning to buy my battery cables from batterycablesusa.com. the terminals on the eg4 battery are small, I think I need to choose a 1/4inch(m6) lug for the battery connector lug. Any thoughts on this?
 
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the most important is protecting the wire... 10 guage wire, 30 amp is fine.

the use of breakers are fine
 
Since it has a the built in DC circuit breaker, do I still need a t class fuse on the main positive battery cable?
Maybe I’m out to lunch but *I* would use the fuse at 115-125% of the max load you will be applying to the battery. Which if I read right will be 100A so I think that 125A in that case would be appropriate. Need is a funny word; the fuse is an insurance policy.
 
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