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Sanity check on solar set-up for camper

compunaut01

New Member
Joined
Nov 28, 2024
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5
Location
Texas
Been following Will Prowse and this forum for a couple years but finally became a member because…

Bought a well-used 1996 Bigfoot 3000 10.11 truck camper this summer. Includes LP furnace, water heater, generator, and (3-way) fridge. Had an ‘aftermarket’ solar system installed but component age was an issue and execution was… mediocre at best. Panels, charge controller, inverter, battery bank. 2 of 3 panels seem good, CC appears designed for lead-acid (or optional ni-cad!), inverter dead, FLA batteries (not OEM size or location) dead/not holding charge.

So, replaced panel (matching voltage of other 2), bought Victron MPPT and two 12V Seikon 100Ah LiFePO4 batteries (sized to fit in original house battery box). Was gifted a refurb EcoFlow Delta Pro; plan to use that connected to camper’s shore power plug for the occasional AC needs so don’t need another inverter. Believe I have the wiring basics down: PV wired in parallel, cables to DC circuit breaker then MPPT, connection to batteries then to (DC) loads via existing OEM fuse box.

Some questions:
- Am I missing anything obvious?
- Are fuses still needed if there’s no inverter pulling large current? If so, where and what size?
- My understanding is that MPPT ‘Batt’ & ‘Load’ connections aren’t really adequate for monitoring power usage or battery SoC; need a shunt for that? If so, why do manufacturers go to trouble to include ’Load’ terminal on SCC but not shunt?
- I think original camper design has generator connected directly to house batteries: genset needs battery boost to start, and it recharges battery when running. Does this scenario still work adequately for Li batteries? What does wiring diagram look like for MPPT, (Li) battery, shunt, DC loads (only), AND generator?

Thanks in advance for everyone’s time.
 
I would highly consider a Victron SmartShunt or BMV712.
That was the first thing I bought for my MotorHome.
Knowing that you are 20ah down vs 150ah down vs a wild guess will cause you to make different decisions on your usage. (90% full vs 25% full). It also helps you to know how long you need to charge up.

Fuses are always necessary - fuses protect wires… what happens if chafing occurs and you rub a positive wire against the frame. A fuse pops. Without a fuse you hope that the BMS will keep working and stay shut off- and hope that if it does get fried - and if it fries it fries closed. Otherwise you have a red hot wire burning its insulation…

As for what size of fuse… what size of wires do you have. Ideally 10 awg wires will have a 30a fuse and a 14awg wire will have a 15a fuse. This is why fuse blocks are important - each wire gets the right size of fuse.
 
If you intend to plug the shore power into the Inverter you must disable the converter out of the system in your trailer otherwise the inverter which is powering the shore power is causing the converter to want to charge your batteries. Consequently the batteries that are being charged are the ones that is drawing power from and it eventually will just drain your batteries down to 0
 
I would highly consider a Victron SmartShunt or BMV712.
That was the first thing I bought for my MotorHome.
Knowing that you are 20ah down vs 150ah down vs a wild guess will cause you to make different decisions on your usage. (90% full vs 25% full). It also helps you to know how long you need to charge up.

Fuses are always necessary - fuses protect wires… what happens if chafing occurs and you rub a positive wire against the frame. A fuse pops. Without a fuse you hope that the BMS will keep working and stay shut off- and hope that if it does get fried - and if it fries it fries closed. Otherwise you have a red hot wire burning its insulation…

As for what size of fuse… what size of wires do you have. Ideally 10 awg wires will have a 30a fuse and a 14awg wire will have a 15a fuse. This is why fuse blocks are important - each wire gets the right size of fuse.
Thanks for your thoughts. Am leaning towards SmartShunt since not much more $ vs. other Bluetooth-capable monitors and I already have Victron MPPT.

Running 12awg from PV panels on camper roof, down inside to DC circuit breaker then SCC. Now thinking 10awg from there to terminal block (+) & shunt (-). Batteries connected to each other (parallel) and terminal block & shunt via 4awg in (OEM) vented fiberglass battery box; can maybe squeeze MPPT in there too.

Original wires from battery box to (OEM) camper fuse block look to be in good shape, as do wires for LP generator. Guess I should add (20a?) fuse between terminal block and MPPT…

Any concerns with genset charging Li batteries via converter? I imagine the voltage levels being too low?
 
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If you intend to plug the shore power into the Inverter you must disable the converter out of the system in your trailer otherwise the inverter which is powering the shore power is causing the converter to want to charge your batteries. Consequently the batteries that are being charged are the ones that is drawing power from and it eventually will just drain your batteries down to 0
Good point. Since my camper’s ‘shore power’ will usually be battery/inverter all-in-one, power would just be moving from one battery source to another (unless all were fully charged). I’ll shut off shore power battery source when AC power isn't needed.
 
concerns with genset charging Li batteries via converter? I imagine the voltage levels being too low?
Some seem to have issues but in theory the converter charge voltages should be OK.
Screenshot_20250104-212130_Chrome~2.jpg
Batteries connected to each other (parallel)
Idealy fit a 'master fuse' at each battery post, before the parallel connection, using a Bluesea MRBF fuse and fuse holder, 150 amp.

It's probable there is battery charging from the vehicle alternator controlled by relays that are enabled when engine is running and connect house batteries to starter battery. Ite usual to replace this charge path with a DC to DC battery charger.
 
Some seem to have issues but in theory the converter charge voltages should be OK.
View attachment 269171
Idealy fit a 'master fuse' at each battery post, before the parallel connection, using a Bluesea MRBF fuse and fuse holder, 150 amp.

It's probable there is battery charging from the vehicle alternator controlled by relays that are enabled when engine is running and connect house batteries to starter battery. Ite usual to replace this charge path with a DC to DC battery charger.
Appreciate your input. If I may: How is the 150a size for the fuse chosen? And what is the benefit of having a fuse at each battery ‘+’ terminal instead of just one at the post where they connect?
 
And what is the benefit of having a fuse at each battery
Worst case is failure in the battery leading to a SC condition. The battery will have a 100A BMS , the master 150 fuses are for last resort conditions, there will be other fuses or breakers protecting cables in the system. Connections something like this,
Screenshot_20250111-134505_Chrome~2.jpgScreenshot_20241109-195340_Chrome~2.jpg
 
Worst case is failure in the battery leading to a SC condition. The battery will have a 100A BMS , the master 150 fuses are for last resort conditions, there will be other fuses or breakers protecting cables in the system. Connections something like this,
View attachment 269343View attachment 269345
Makes sense. Pretty confident the positive load wires have OEM fuses; that part of the installation looks original.
 

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