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diy solar

Our Truck Camper solar

TCgreg

Solar Enthusiast
Joined
Sep 21, 2019
Messages
116
We have been truck camper owners for almost 25 years. Recently I took an interest in developing a generator free truck camper that would power all our AC circuits on our new unit. After doing a fair amount of research this is what we built a couple years ago.

This is a 2018 Host Mammoth slide in truck camper that we picked up in Oct 2017.

On the roof are (6) 180 watt mono solar panels wired in parallel.

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The panels feed a Victron 150/85 solar controller mounted into the campers basement.

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For a battery bank I went with (24) CALB 3.2v@100Ah cells arranged into two 300Ah banks

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Rather than a top balancing BMS I opted for a bottom balance solution. I used a cell pro8 to accurately discharge the cells.

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I utilized what would have been the generator compartment to house the batteries as well as the distribution busbars/circuit breakers, battery disconnect and Victron low voltage disconnect.

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The batteries are connected to a Magnum 2800 watt inverter that intercepts the 30 amp feeder from the exterior power plug. This allows full function of all the AC circuits on the camper. It is mounted in what would be the campers battery compartment. Very convenient install as the AC power passes through this compartment.

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There is a pass through from the roof to the basement right through the campers information center. Adding the inverter remote, battery monitor, solar panels circuit breaker and SCC remote controller were easy.



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We have been very happy with our results. Within reason the camper is essentially always "plugged in" We regularly use a variety of AC appliances such as the roof air, Keurig, instant pot, a 1600 watt large electric toaster oven, the 6 gallon water heater, ice maker, electric blankets etc. I definitely do not miss having a generator. The propane gensets that these campers typically come with are noisy, smelly and hungry for gas.

Cheers!
 
Beautiful!! Bravo! I love it. You really maxed out the roof with panels too. Smart move with cell pro8 to bottom balance manually. Looks good
 
Nice work! Tell me more about your BMS and contactor setup please. Any wiring diagram to show as I'm curious about your breaker placements in the picture. Do you do any alternator charging?
 
Nice work! Tell me more about your BMS and contactor setup please. Any wiring diagram to show as I'm curious about your breaker placements in the picture. Do you do any alternator charging?

Thanks. No alternator charging. The solar has been enough. The diagram doesn't show an 80 amp circuit breaker between the dc distribution panel and the pos busbar. Also a 250 amp T fuse for the inverter rather than the 400amp shown.

No top balancing BMS

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Thank you sir. I would like to pick your brain if you don't mind. So what you did was bottom balance the cells and no BMS after that? No concern on how the system will deal with a dead cell? No cell balancing devices at all? I see you are using a Victron MPPT but no temperature protection? Are you concerned about cold weather in your generator compartment that is not heated? It appears you are charging through the Victron battery protect and I thought that was not allowed?
Thanks for sharing your time and experience.
 
Thank you sir. I would like to pick your brain if you don't mind. (1) So what you did was bottom balance the cells and no BMS after that? (2) No concern on how the system will deal with a dead cell? (3) No cell balancing devices at all? (4) I see you are using a Victron MPPT but no temperature protection? (5) Are you concerned about cold weather in your generator compartment that is not heated? (6) It appears you are charging through the Victron battery protect and I thought that was not allowed?
Thanks for sharing your time and experience.

Your welcome. :)

1. Yes
2. No
3. Just bottom balanced. Max charging voltage within safe limit for all cells. All cells balanced within the voltages they are allowed.
4. Correct
5. Compartment is heated by basement heat supply. If we aren't freezing neither is the battery plus we are fair weather travelers.
6. Never heard of that and not mentioned in the instructions. Been working fine for 2 years. Can you link me to a source for that?
 
What are the width and length dimensions of those 180w panels? Link?

They are 180 watt Grape solar. Their website has all the stats.

I got your PM. My total cost for everything including specialty tools like the cell pro 8, cable crimpers, cable cutters for large cable etc. was a bit under 9k. A build like this could be done for less with lower cost components. My inverter charger was pricey as was the Victron solar charger.The panels are very expensive per watt but they fit the roof space available. On the other hand I saved about $2500 bucks on battery vs. drop-ins available at the time. The system was built back in 2017.
 
6. Never heard of that and not mentioned in the instructions. Been working fine for 2 years. Can you link me to a source for that?


See answer, although the setup is different the fundamentals are the same. Also, due to the nature of the circuit Victron uses you should see about double the voltage drop across it when current flows in reverse.

Look at the bold writing above the green button.

I would just have your positive wire from the mppt bypass the battery protect, it's not buying you anything AND if it ever does open the way it's currently wired your not able to charge (unless I'm missing something).
Keith
 

See answer, although the setup is different the fundamentals are the same. Also, due to the nature of the circuit Victron uses you should see about double the voltage drop across it when current flows in reverse.

Look at the bold writing above the green button.

I would just have your positive wire from the mppt bypass the battery protect, it's not buying you anything AND if it ever does open the way it's currently wired your not able to charge (unless I'm missing something).
Keith
Thanks for the info Keith.

This conversation wasn't around when I built my system nor was Victrons warning. I will probably move the BP to handle only the DC house circuit loads and look into a different LVCO solution to replace the whole house disconnect. The inverter already has a LVCO. My Battery monitor has a relay that can be used (I believe) for a powered disconnect.

The inverter also has a charger so rerouting just the solar charger to bypass the BP wouldn't be a complete solution.

Thanks again.
 
Thanks for the info Keith.

This conversation wasn't around when I built my system nor was Victrons warning. I will probably move the BP to handle only the DC house circuit loads and look into a different LVCO solution to replace the whole house disconnect. The inverter already has a LVCO. My Battery monitor has a relay that can be used (I believe) for a powered disconnect.

The inverter also has a charger so rerouting just the solar charger to bypass the BP wouldn't be a complete solution.

Thanks again.

Greg, I am in the same predicament, much smaller system. I've been using the a BP-100 to isolate the battery charger from the battery based on a charger high voltage set point and a camper battery low voltage set point. Running battery charger current thru the BP-100 backwards or OUT to IN studs. I will be interested in your solution.

I hope to add an inverter/charger pass thru device, more battery, more solar as time goes by. Charging currents will go up whether from solar or B/C.
 
Greg, I am in the same predicament, much smaller system. I've been using the a BP-100 to isolate the battery charger from the battery based on a charger high voltage set point and a camper battery low voltage set point. Running battery charger current thru the BP-100 backwards or OUT to IN studs. I will be interested in your solution.

I hope to add an inverter/charger pass thru device, more battery, more solar as time goes by. Charging currents will go up whether from solar or B/C.

There are a few ways you could trigger a solenoid disconnect by voltage. I am leaning toward buying one of these. Not very creative and pretty expensive for what it is but looks like it would do the trick. They make 80 and 200 amp kits as well.

https://thorpowerproducts.com/product/thi-lvd-500-kit/
 
There are a few ways you could trigger a solenoid disconnect by voltage. I am leaning toward buying one of these. Not very creative and pretty expensive for what it is but looks like it would do the trick. They make 80 and 200 amp kits as well.

https://thorpowerproducts.com/product/thi-lvd-500-kit/
Looks like it has a 12v Max low voltage disconnect, 9% SOC for battleborn LIFePO4 battery recovery is 12.2 Vdc. High voltage disconnect is 16.5 v recovery at 15.0 volts, I think its too high.
 
Looks good. What will you trigger it with?
Coil power bistable < 60 W (50 ms), scheme has three wire switch setup, battery -, Momentary switch off and momentary switch on.
I don't think the BMV712 can meet that power level thru its contacts. So I do not know.
 
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