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Another wiring diagram to review!

waphals

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Feb 22, 2021
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I am currently converting a Ford Transit 250 and have spent quite some time these last few weeks trying to figure out how the electrical will work with a lot of hours reading this forum as well as other places. I know a lot of diagrams get posted here so I tried to make mine as clean as possible and easy to read as I'm a very visual person and hopefully it can help someone out in the future.

The system we're currently going for:
- 400w solar but possibly increasing to 600w which is why I went for a 60a controller
- Alternator through the existing 12v battery
- Possibly adding shore in the future if we think we'd benefit after testing it out

As far as an energy audit, I have the items listed in the diagram and think the ideal amount of battery would be 300-400ah. Still working out what batteries to get...

Would love any feedback to make sure I don't kill us or to see if I'm upsizing any breakers or fusing too much to hopefully cut some costs. I had the inverter upsized just to play it safe since we may have some 1200-1500w draws at times, or find that we would like to. I have the induction cooktop in "??s" because we're currently on the fence on going with propane or not.

Please see below and looking forward to hearing any input.

<blockquote class="imgur-embed-pub" lang="en" data-id="a/CtHit8e" ><a href="//imgur.com/a/CtHit8e">Wire Diagram - 5/19/2021</a></blockquote><script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>

Thanks!
 

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  • Wiring Diagram.pdf
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Since you are planning on a 12V battery bank, then you probably need to replace a lot of the 4AWG wire with much thicker wire. A 3000W inverter at 12V can pull 250A. For 250A, using high quality 105ºC wire, you need 2/0AWG if you keep the lengths reasonable. This affects all of the wire between the inverter and battery.

The basic approach is to choose the correct size wire based on the max current, the number of wires in the bundle, the insulation rating, and the length of wire. Then pick a fuse that is between the max amps the wire can safely handle and the amps you will actually be sending through the wire. A 300A fuse is way too high for 4AWG wire. Even if 4AWG wire was safe (it's not) for the inverter, it can't handle anywhere near 300A. The wire would burn long before the fuse did its job. At most, 4AWG should have a 150A fuse.

The wire for the lights can be 16AWG or even 18AWG given the very low wattage of the LEDs. 12AWG works of course but it is overkill.

The 4AWG from the charge controller can be lowered to 6AWG if you want. 6AWG can safely handle the 60A.

Maybe others can add to this but that's what I see at first glance.
 
Awesome, thank you for that - it makes sense. I'll increase all of the wire from the inverter to the battery to 2/0. Would I be correct in assuming that the negative wires from the battery would need to be increased as well from the battery to the chassis?

I'm modifying the 12AWG on the LED's to 14AWG because that's the smallest gauge I've purchased

I'll switch the 4AWG to 6AWG if it works out when buying the wire but I've been trying to stick to same sizes where I'll have excess when I purchase. I currently only have wire planted for the appliances or sleeves ready and still need to purchase all of the main components.

Thank you!
 
I'll increase all of the wire from the inverter to the battery to 2/0. Would I be correct in assuming that the negative wires from the battery would need to be increased as well from the battery to the chassis?
Yes, all positive and negative wires between the batteries and the inverter (and shunt, switch, and fuses on those paths) need to be larger. BTW - my suggestion of using 2/0 for the inverter assumes it will never go over 3000W/250A. Many inverters can handle much higher surges for some brief period of time (30 seconds maybe). If that's a possibility you may actually need 4/0 wire.

I'll switch the 4AWG to 6AWG if it works out when buying the wire but I've been trying to stick to same sizes where I'll have excess when I purchase.
Using larger wire in places is normally fine (other than being more expensive and heavier) but keep in mind the max wire size that each component can handle. For example, the charge controller may only accept wire up to 6AWG. You need to look at the manual and see if can handle your proposed 4AWG. For ring terminal connections it generally doesn't matter since you can get the proper sized ring terminal.

One other observation. The 100A breaker just before the 12V fuse panel may be oversized. Of the 12V loads you have listed, their respective fuses only total 73A. So even if all of your 12V loads were on full, you will be pulling less than 70A through the 12V fuse panel. So you probably only need a 70A (or 80A) breaker there. To be sure, add up how much current all of your 12V loads could possible use, then multiply by 1.25 to get the proper breaker size.
 
Even with 600 watts of solar panels, your solar charge controller is oversized at 60 amps. 600 watts / 12 volts = 50 amps. That's the maximum, optimistic, full sun, no clouds, clean panels day. You could get away with a 50 amp controller. I have 640 watts on my roof and use a 50 amp controller. While I don't track historical output, I doubt mine had ever hit the full 50 amp limit except on very cold days. It's not wrong to use a 60 amp controller. If a 50 amp controller can save you some money, it might be worth it.

The 100 amp circuit breaker on the downstream side of your 60 amp B2B charger is too high. 75 amps is more appropriate.

I agree with rmaddy's suggestions, especially your undersided wires.

My MPPT has a spec of 6 awg on the terminals. I used 6 awg with ferrules. It was a tight fit. 4 awg would not have fit.
 
Thanks rmaddy, I'm going to adjust my diagram to the larger wire sizes and see what wire the inverter requires. I haven't actually purchased anything but I'm sure I can find the manual online. Also appreciate the input on the breakers, that's nice that I will be able to downsize them as the costs of them definitely surprised me!

Thanks HRTKD, that makes total sense with the solar charge controller. This stuff is overwhelmingly complicated but that is a pretty simply explanation! It'll definitely save me about a $100 which I will take.

Sounds like I need to beef up my wires and downsize my breakers!
 
Really appreciate the previous feedback - it's been a minute but I've finally made a few updates per yall's recommendations and some more research.
-Downgraded to a 2000W inverter
-Adjusted all wire from inverter to ground as 2/0 wire. I believe I would be fine with 1/0 but I'm not 100% confident so better safe than sorry
-Downsized fuse from inverter to 175A because 2000/12 is 167?
-Downsized MPPT to 50A. I'm still using a Renogy but am considering Victron? Though I don't think the Victron is necessary, as it's more expensive, unless I use a Victron BTB or Inverter, yeah?
-Adjusted breakers from solar and BTB to appropriately fit the components

If the max output of my batteries is 150A am I good with the terminal fuses being 300A?
I think I should have my diagram down now... but we'll see!

Also, I sleeved 10 AWG to one of my fans just in case we decide to upgrade to a DC AC eventually. Would this need any kind of breaker or something or is it okay to connect a 10 AWG to an either 16 or 18 AWG wire on the fan?

Thanks!

InDmnvE.jpg
 

Attachments

  • Wiring Diagram.pdf
    1.1 MB · Views: 4
It is probably better to use a 200A fuse for the 2000W inverter. 2000W / 12V = 167A * 1.25 = 208A. A 175A fuse could nuisance trip if you actually use the full 2000W.

How are your solar panels going to be connected? Series or parallel? And what size PV wire will run from the panels to the charge controller? Do the math based on the panel configuration. I think your 60A breaker between the panels and charge controller is likely too high. The 60A breaker between the charge controller and bus bar is fine.

I notice you are planning on four 12V outlets. You show a 15A fuse. Is that one 15A fuse for all 4 outlets or one 15A fuse per outlet? A single fuse for all four is a bit low. I would wire two outlets in parallel giving each pair their own 15A fuse.
 
Check the input requirements of the DC-DC charger. Verify the 80 amp feed breaker has some head room and the alternator is not going to be maxed out.

Have you verified the solar controller will provide the correct voltage and charging profile you expect? Some have limited adjustments and are profiled on mostly lead-acid.

2/0 should be good for 330 amps so I would reduce the battery fuse to 200 and skip the second 175 to the inverter.
 
2/0 should be good for 330 amps so I would reduce the battery fuse to 200 and skip the second 175 to the inverter.
Why skip the inverter fuse? It should be there to protect the inverter wiring. The battery fuse will protect the battery wiring.

Since the inverter can pull over 160A and the DC fuse panel can pull close to 100A I wouldn't suggest lowering the battery fuse to only 200A. If most of the DC loads are on and the inverter is running high, a 200A fuse may needlessly blow.
 
rmaddy,

I'll upgrade the fuse to 200A from the inverter, I neglected the 1.25

I was going to connect them in parallel with 8 awg to the MPPT and 6 awg from the MPPT . I guess if I have 600W of 12V solar panels I'll be good with a 30A breaker between them and the MPPT?

I was actually planning on 15A fuse per outlet but my math might be off with the total draws - but if 15A per outlet is overkill, I can definitely wire them together to share the fuse.

time2roll,

The DC-DC is 60A so that's where the 80A came from, alternator should not be maxed out with the ford transit. I haven't verified this with the solar controller, so I'll have read up on the Renogy since I think I'll be going with it.
Regarding the battery fuses, that sounds good if I can avoid the second fuse but I need to knowledge myself on terminal fuses as they still confuse me a good bit.

Thanks guys!
 
The battery fuse is the same as terminal fuses, right? So if I have 2 batteries I'll have 4 total fuses? If so, would all blow at once?
 
Why skip the inverter fuse? It should be there to protect the inverter wiring. The battery fuse will protect the battery wiring.
The battery fuse and the inverter fuse are in series so the second fuse is redundant. OK unless the battery fuse is per battery but then 350 amps seems too high.
 
I was going to connect them in parallel with 8 awg to the MPPT and 6 awg from the MPPT . I guess if I have 600W of 12V solar panels I'll be good with a 30A breaker between them and the MPPT?
I'm not up on the details of wiring three panels in parallel but you might need a combiner box. It depends on the specs of the panels. I would do some more research on the best way to wire and fuse panels in parallel.

I was actually planning on 15A fuse per outlet but my math might be off with the total draws - but if 15A per outlet is overkill, I can definitely wire them together to share the fuse.
15A per outlet works too. You specs 10AWG wire so the fuse size is fine. Look at all of the things you might plug into the outlet and see what the max amps are.

Do keep in mind that given your other DC loads, you won't be able to actually use all four of those outlets at a full 15A at the same time. But using one or two at the full 15A will be fine.

Regarding the battery fuses, that sounds good if I can avoid the second fuse but I need to knowledge myself on terminal fuses as they still confuse me a good bit.
I just realized your diagram shows four 300A battery fuses. I'm not sure why you have four. I'm using just one but I have two batteries in series. Perhaps you need two with two batteries in parallel. I'm not in a position to clarify that specific need.
 
The battery fuse and the inverter fuse are in series so the second fuse is redundant.
That logic could then be applied to the DC fuse box breaker and the charge controller breaker, etc. Each branch should have its own fuse/breaker.

OK unless the battery fuse is per battery but then 350 amps seems too high.
I just realized the OP plans on multiple battery fuses for parallel batteries so I'm now not in a position to offer the best advice on the size of the battery fuses. I leave that to others with better knowledge in that area.
 
That logic could then be applied to the DC fuse box breaker and the charge controller breaker, etc. Each branch should have its own fuse/breaker.
Yes the breaker on the panels feeding the controller is not needed but provides a convenient switch to cut power if needed.

Much of this depends on distance. If the connection is well protected and within 18" the fuse is not really needed in some cases. Certainly if the wire is long and goes between compartments or blind areas it needs a fuse at each source of power.

Similar with the B2B. The feed breaker should be close to the vehicle power source connection and the charge wire should be close to the bus to protect from the power from the house batteries. And again if the B2B is mounted close to the bus maybe no fuse is needed on the charge wire.

Hard to get some of this placement from the drawing.
 
I'm not up on the details of wiring three panels in parallel but you might need a combiner box. It depends on the specs of the panels. I would do some more research on the best way to wire and fuse panels in parallel.


15A per outlet works too. You specs 10AWG wire so the fuse size is fine. Look at all of the things you might plug into the outlet and see what the max amps are.

Do keep in mind that given your other DC loads, you won't be able to actually use all four of those outlets at a full 15A at the same time. But using one or two at the full 15A will be fine.


I just realized your diagram shows four 300A battery fuses. I'm not sure why you have four. I'm using just one but I have two batteries in series. Perhaps you need two with two batteries in parallel. I'm not in a position to clarify that specific need.
I thought having a fuse on each separate terminal was extra safe from what I've seen.
Yes the breaker on the panels feeding the controller is not needed but provides a convenient switch to cut power if needed.

Much of this depends on distance. If the connection is well protected and within 18" the fuse is not really needed in some cases. Certainly if the wire is long and goes between compartments or blind areas it needs a fuse at each source of power.

Similar with the B2B. The feed breaker should be close to the vehicle power source connection and the charge wire should be close to the bus to protect from the power from the house batteries. And again if the B2B is mounted close to the bus maybe no fuse is needed on the charge wire.

Hard to get some of this placement from the drawing.
The wire from the vehicle's battery to the B2B will be about 13 feet, while B2B to battery pretty short. The panels to the MPPT will be around 9 feet. All of the electrical will be mounted to a panel in the back of the van
 
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