Wiring check

[Nicks RV]

wondering if i could get a second opinion on my wiring plan? As this is a trial run summer to see how much i will actually use it, i'm only planning on 12v power for boondocking, and possibly a small inverter later on.

my main concerns are breaker sizes and placements, as i have read conflicting ideas on the net.

All comments are welcome.

Thanks

[twinboat]

In red, 10 gauge wire is rated for 30 amps, solar output will be less. No need for a breaker, but if you use one it should be 30 amp.

In blue, the batteries have the potential to melt 4 gauge wires if shorted. Thats an important spot for a breaker. Find the amp rating of 4 gauge wire and use that size breaker, close to the battery.

A breaker between the distribution block and controller is handy as a switch. With 10 guage wire, 30 amp breaker.

I see your proposing using 8 guage wire to house panel. That breaker needs to be rated for that guage wire. 60 amps may be fine, you can look it up.

A 2000 watt inverter will need its own cables and fuse. 2/0 gauge and 250 amp fuse.

[Nicks RV]

twinboat,

thanks for the reply. if a fuse is not needed from the solar array, then ill leave it out.

For some reason I didn't think of fusing the batteries, but that's why i asked for a second look, and I will be adding one for sure. I am now wondering if i should go bigger on the battery cables tho??

The RV came factory wired from the battery tray to the 12v fuse panel with 8ga wire...I just planned on hooking those leads to the distribution block. Should I upgrade that wiring as well??

also I am seeing confusion as to what is the proper size fuse for 8ga wire.

FUSES
8 awg 50 amps

vs

https://forum.nachi.org/t/50-amp-breaker-8-awg-cu/24075

8 AWG may carry a maximum of 70 Amps in free air, or 50 Amps as part of a 3 conductor cable

[twinboat]

Run 2/0 cable from the batteries to a 250 amp fuse, disconnect, and then the distribution block ( bus bar ).

From that point you can run smaller guage wires, fused near the bus bar, to your controller and house loads.

When you install an inverter, just connect it up to the bus bar. Its already properly fused.

[twinboat]

Here is a bus bar that can handle the load.

[DavidEM]

As noted in the comments above, fuses or breakers are designed to protect the wire from faults and should be placed near to the source of current. For main battery circuit to the distribution block, place it near the battery. With 4 gauge wire you can use a 160 A fuse/breaker. BTW the sizes I am noting are based on the wire's ampacity. Home building codes specify less, probably as much for voltage drop reasons.

From the distribution point you need breaker fuses on each wire as those wires are smaller than the 4 gauge. Use a max of 60 A for 10 gauge and 80 A for 8 gauge. For your inverter, if you use 4 gauge wire, you don't need an additional fuse/breaker because the battery's breaker will protect it. But you may want to consider upping the main battery wire size as #4 gauge may by too small for voltage drop and maximum current to the inverter.

David

[RVingNow]

I would suggest you route the output of the Renology controller through a breaker to the AGMs directly. This gives you the option of leaving the coach with the disconnect switch off but solar on the AGMs.

[RVingNow]

Well, in for a penny..... nice choice on the Victron BMV-712. You should consider the Victron MPPT controller to mate with it. I think the the wireless features are awesome.

[Persistent]

Good advice above.

Locate the inverter, charger in the 12 volt panel, and the solar controller within 2 feet of the battery (not in the battery compartment for safety). Longer distances require larger wire size.

Use 4/0 gauge wire. See inverter installation instructions for wire size. Inverter will draw about 180 amps from the batteries at full power.

Get a big 180 amp Bussmann circuit breaker. It will double as a battery disconnect. Battery bank to breaker 4/0 awg. Breaker to buss 4/0 awg. Buss to inverter 4/0 awg. (The breaker needs to be sized to match the wire gauge.)

Converter/controller/fuse panel probably has appropriate size fuse for a couple of feet. Use 10 awg for 30 amps. For much longer wire add appropriate fuse for wire size near the new buss.

Solar controller probably has its own circuit protection. See installation instructions.

Inverter probably has its own circuit protection. See installation instructions.

Be sure to increase battery ground circuit to frame to 4/0 awg.

Reconsider inverter size. Check specification for maximum current from battery. You may need to double your battery bank size for 180 amps. Or, you could use a 1000 watt inverter and get buy with 2 awg wire instead of 4/0 and a smaller main breaker/disconnect. Again, see inverter installation instructions for wire size.

My pair of 100 amp hour group 31 AGM batteries barely support 85 amps needed for a 1000 amp inverter. My inverter requires 2 gauge wire.

I wish you good luck and happy trails ahead!

[SteveJ.]

Originally Posted by RVingNow

Well, in for a penny..... nice choice on the Victron BMV-712. You should consider the Victron MPPT controller to mate with it. I think the the wireless features are awesome.

And the Victron wireless temperature/voltage sensor, if applicable.

I just installed the Victron Smart solar MPPT 30 amp controller along with the sensor. Good stuff, easy to work with. This controller does have built in temp sensing but that is only accurate if the controller is mounted in the same climate as the batteries. I chose to mount my controller inside and am using lead acid batteries mounted outside, hence the need for a remote sensor. Indoor AGM or lithium batteries would negate the need for the remote sensor, assuming mounting in same area.

Unfortunately for me, I had already installed a fake BMV-712 from Amazon. It works fine but there is no smart communication with the Victron stuff.