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Discussion Starter · #1 ·
Hi Folks,
Would certainly appreciate any feedback on my electrical design before I start wiring my PM. I've done a fair bit of research (which can sometimes leave your head spinning) and I think this should do but certainly appreciate the input of those who have more experience. My DC load will be pretty light, around 130ah, and if need be, down the road, I might add another 100w solar panel and 100ah battery to the build.
Thanks
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
Nice diagram -- a few thoughts...

The #16 wires to some of the 12 volt appliances may be too low for voltage drop.
Use the BlueSea Circuit Wizard to check them. For example, if the fridge draws 5 amps, and the wire run is 10 ft (20 ft total), then for a 2% voltage drop, the Circuit Wizard wants #12 wire.

On mine, I did not use any wire less than #14 -- some of the runs could be served with lsmaller gauges, but just from the standpoint of mechanical strength and standardizing on fewer wire sizes, I only used #14 and #12 for all the fan, fridge, lights, ... loads. But, nothing wrong with #16.

All of your fuses should be located as close as possible to the current source (battery), so the fuse that protects the wire from the van battery to the B2B should be mounted as close as possible to the van battery as possible (no 10 ft away). This is to protect against a short of the wire to ground between the battery terminal and the fuse.

If you have not yet bought your 120VAC breaker panel, I'd have a look around for one. I was not able to find one that was not quite large and clunky and ended up going with a combined DC and AC panel made for RV's
Honestly, for the very little we end up using AC applicances in our van, I'd have skipped the AC panel and just gone with a plug strip.

Check the max current drain that your 100 AH battery will support. Some of them are 100 amps max current draw, and that will be pretty close to what the 1000 watt inverter at 85% efic will pull.

Not sure what the gadgets between the house battery terminal and the busbars are?
If they are switches, do you really want one in the negative wire?
The 3 ft wire from the house battery + terminal to the busbar should really be protected from a short to ground with a fuse right at or very near the battery terminal. On the other hand, if you can locate the busbar within 6 inches of the battery terminal, then no fuse is required.

I would run all of your wire gauges through the BlueSea Circuit Wizard. It will check for both max current and voltage drop. Some of those #4's may not need to be that big?

Gary
 

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100A fuse for inverter: Can you just put that right on the battery terminal, since you're battery is probably limited to 100A anyway?
As for fuses on battery terminal, I ended up just getting a terminal mounted fuse block with 2 fuses and ran one to the inverter and connected DC, solar, and B2B charger directly to the other. Eliminated the positive bus bar (I put the kill switch on negative).
AC: You can't get 15A from the inverter anyway, so why not just run 2 outlets on one circuit?

For DC loads, I used a breaker instead of a fuse. This has come in handy many times over the course of the build to easily shut off DC loads while working on wiring various components. I also have a breaker coming in from the solar so I can disconnect solar from charge controller before switching off my main batteries. Last, I added a breaker between house batteries and B2B charger, just out of caution to make sure it isn't powering anything when my house battery switch is off. Although it shouldn't be anyway if the engine isn't running. That may have been overkill.
 

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Discussion Starter · #7 ·
Hi,
Nice diagram -- a few thoughts...

The #16 wires to some of the 12 volt appliances may be too low for voltage drop.
Use the BlueSea Circuit Wizard to check them. For example, if the fridge draws 5 amps, and the wire run is 10 ft (20 ft total), then for a 2% voltage drop, the Circuit Wizard wants #12 wire.

On mine, I did not use any wire less than #14 -- some of the runs could be served with lsmaller gauges, but just from the standpoint of mechanical strength and standardizing on fewer wire sizes, I only used #14 and #12 for all the fan, fridge, lights, ... loads. But, nothing wrong with #16.

All of your fuses should be located as close as possible to the current source (battery), so the fuse that protects the wire from the van battery to the B2B should be mounted as close as possible to the van battery as possible (no 10 ft away). This is to protect against a short of the wire to ground between the battery terminal and the fuse.

If you have not yet bought your 120VAC breaker panel, I'd have a look around for one. I was not able to find one that was not quite large and clunky and ended up going with a combined DC and AC panel made for RV's
Honestly, for the very little we end up using AC applicances in our van, I'd have skipped the AC panel and just gone with a plug strip.

Check the max current drain that your 100 AH battery will support. Some of them are 100 amps max current draw, and that will be pretty close to what the 1000 watt inverter at 85% efic will pull.

Not sure what the gadgets between the house battery terminal and the busbars are?
If they are switches, do you really want one in the negative wire?
The 3 ft wire from the house battery + terminal to the busbar should really be protected from a short to ground with a fuse right at or very near the battery terminal. On the other hand, if you can locate the busbar within 6 inches of the battery terminal, then no fuse is required.

I would run all of your wire gauges through the BlueSea Circuit Wizard. It will check for both max current and voltage drop. Some of those #4's may not need to be that big?

Gary
Thanks for the input. I'm going to leave my LED's on 16 guage but will switch to 12 guage for everything else and yes I'll put my fuses as close as possible to the battery. I had planned on 2 fuses for the B2B, one 70a located on the van battery positive post as I've seen a number of other folks do in this forum and a 2nd 40amp ANL fuse near the house battery. I hope that's not overkill but thought it was best to be safe. And yes those 2 gadgets on either side of the house battery are battery disconnects. I've seen similar suggestions on other diagrams that folks have posted, but if you are saying the one leading from the negative post is not required then I'll eliminate it. My busbar might be a little further away then 6" so what size of fuse are you suggesting for the + terminal? Thanks for your suggestions Gary.
Ron
 

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I had planned on 2 fuses for the B2B, one 70a located on the van battery positive post as I've seen a number of other folks do in this forum and a 2nd 40amp ANL fuse near the house battery. I hope that's not overkill but thought it was best to be safe. And yes those 2 gadgets on either side of the house battery are battery disconnects. I've seen similar suggestions on other diagrams that folks have posted, but if you are saying the one leading from the negative post is not required then I'll eliminate it.
Your B2B needs one fuse on the B2B input cable at the van battery, and one at the B2B on the output cable. Size those cables and fuses to B2B input/output specs. Fuses go on positive wires/cables at the power-source end. And you only need a battery disconnect switch on the positive cable, too. Negative wires don't need fuses or switches.
 

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2014, 138WB, High Roof, Gas, SW MT
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Thanks for the input. I'm going to leave my LED's on 16 guage but will switch to 12 guage for everything else and yes I'll put my fuses as close as possible to the battery. I had planned on 2 fuses for the B2B, one 70a located on the van battery positive post as I've seen a number of other folks do in this forum and a 2nd 40amp ANL fuse near the house battery. I hope that's not overkill but thought it was best to be safe. And yes those 2 gadgets on either side of the house battery are battery disconnects. I've seen similar suggestions on other diagrams that folks have posted, but if you are saying the one leading from the negative post is not required then I'll eliminate it. My busbar might be a little further away then 6" so what size of fuse are you suggesting for the + terminal? Thanks for your suggestions Gary.
Ron
hi,
Yes, you do need both of the fuses (or breakers) in the line from the van battery to the B2B and then on to the house battery. The reason is that you have heavy duty current sources at both ends - the van battery at one end, and the house battery at the other end. If you don't have a fuse at both ends of this line, then a short to ground will get unlimited current from one of the two batteries. In most van layouts, this is the only line that requires fuses at both ends. Its not over protection.

One thing to remember is that fuses are there to protect the wiring, so be sure that your fuse value limits the current on any wire to a value less than the ampacity (max current) rating of the wire. I'm not clear why the two fuses here should be so different in value as the current on either side of the B2B should be about the same? Maybe I'm missing something?

Either one of your two switches will disconnect all of your loads, so only one is needed. The extra one probably does no harm, but it serves no purpose and its likely to lead to confusion at some point.

If the busbar is just a little more than 6 inches from the battery terminal, then I'd not worry about a fuse in this line. The 6 inches comes from the NMEA marine electrical code -- its not cast in concrete. Its just that this wire from the battery terminal to the busbar is not protected from a short to ground - so, just make sure that this is very unlikely.

edit: did not see Steve's post before I did the above - good advice.

Gary
 

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Discussion Starter · #14 ·
hi,
Yes, you do need both of the fuses (or breakers) in the line from the van battery to the B2B and then on to the house battery. The reason is that you have heavy duty current sources at both ends - the van battery at one end, and the house battery at the other end. If you don't have a fuse at both ends of this line, then a short to ground will get unlimited current from one of the two batteries. In most van layouts, this is the only line that requires fuses at both ends. Its not over protection.

One thing to remember is that fuses are there to protect the wiring, so be sure that your fuse value limits the current on any wire to a value less than the ampacity (max current) rating of the wire. I'm not clear why the two fuses here should be so different in value as the current on either side of the B2B should be about the same? Maybe I'm missing something?

Either one of your two switches will disconnect all of your loads, so only one is needed. The extra one probably does no harm, but it serves no purpose and its likely to lead to confusion at some point.

If the busbar is just a little more than 6 inches from the battery terminal, then I'd not worry about a fuse in this line. The 6 inches comes from the NMEA marine electrical code -- its not cast in concrete. Its just that this wire from the battery terminal to the busbar is not protected from a short to ground - so, just make sure that this is very unlikely.

edit: did not see Steve's post before I did the above - good advice.

Gary
Excellent, I appreciate the advice. Thanks again.
 

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Discussion Starter · #15 ·
Your B2B needs one fuse on the B2B input cable at the van battery, and one at the B2B on the output cable. Size those cables and fuses to B2B input/output specs. Fuses go on positive wires/cables at the power-source end. And you only need a battery disconnect switch on the positive cable, too. Negative wires don't need fuses or switches.
Excellent, thanks Steve.
 
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