Wiring diagram check

[dsaint1884]

I appreciate all the help this forum has given me thus far. I think I have an understanding of what I'd like to do. Could you please look over this wiring diagram and see if anything looks off to you? I'm using 2awg cables for a lot of the heavier load connections which I realize may depend on the cable length. Is it overkill? Is it enough? Everything (MPPT, batteries, bus bars, inverter, fuse box, etc) will be close together near the wheel-well of the van it's going in.

I also have only one "ground" connection in the system for chassis ground coming out of my bus bar.

Thank you in advance!

 

[HRTKD]

The breaker between PV and MPPT is too large. 25 amp is about right. Be sure you're using a dual pole breaker rated for DC.

The OCP between the MPPT and bus bar is too small. It should be 40 amp x 1.25 = 50 amp. I recommend using a breaker in this position instead of a fuse. You will need to shutdown the circuit for maintenance and a breaker is easier to turn off.

200 amp fuse to the inverter is high. 1000 watts x .85 inverter efficiency / 12.8 volts = 66 amps.

Make sure your common bus bars and your switch are rated for enough amps.

 

[John Frum]

The largest wire that you can comfortably land on a fuse box branch position is 10 awg and the max fuse size is 30 amps.
Do you really need 8 awg for the fridge?

 

[dsaint1884]

The breaker between PV and MPPT is too large. 25 amp is about right. Be sure you're using a dual pole breaker rated for DC.

Do I need a fuse here? I was under the impression that my 2s2p setup can't exceed the wire capacity or what the MPPT should be able to handle. I'll be switching to a dual pole breaker, but the amps are so high it wouldn't provide any current protection, just disconnect.

https://www.amazon.com/dp/B096315TSJ?psc=1&ref=ppx_yo2ov_dt_b_product_details

The OCP between the MPPT and bus bar is too small. It should be 40 amp x 1.25 = 50 amp. I recommend using a breaker in this position instead of a fuse. You will need to shutdown the circuit for maintenance and a breaker is easier to turn off.

Dang, ok thank you. That's the one that Renogy (who I bought the full kit from) supplied to me, so I was going to use it. I'll up it to a 50a breaker. Thank you.

200 amp fuse to the inverter is high. 1000 watts x .85 inverter efficiency / 12.8 volts = 66 amps.

Gotch ya, I was putting a fuse on for the peak surge capacity of the inverter which is 2000w. I went with 1.25x, you scaled down for inverter efficiency. Should I be using the 66amps or 2000 surge watts x .85 / 12.8v getting to 130amps? Either way, the 200 is too large, ty.

https://amazon.com/gp/product/B07JMQ27WJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Make sure your common bus bars and your switch are rated for enough amps.

I'm using these for bus bar and switch, both 250a or higher, and I have a 250a fuse coming off the battery so that's the max the system should be able to see:

Bus Bar - 250a

https://smile.amazon.com/gp/product/B07THLYYH3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Switch - 350a

https://smile.amazon.com/gp/product/B000MMC914/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[dsaint1884]

The largest wire that you can comfortably land on a fuse box branch position is 10 awg and the max fuse size is 30 amps.

Thank you for catching that. This is what the specs say: Max Amps: 100A per block, 30A per circuit.

https://smile.amazon.com/gp/product/B001P6FTHC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I was thinking that if I had say, three of the circuits each pulling 30a then I might get 90a or more into the block itself and needed the bigger wire. Realistically I'm not going to be close to 100a through the block so I can probably downside but I was attempting to allow room to scale up if I did need the extra power. Am I thinking about that right when I read the specs at 100a per block?

Do you really need 8 awg for the fridge?

Not sure? I'm trying to account for voltage drop and making sure there's as little as possible between the battery and the fridge. It's about 25ft of wire one way unfortunately. I ran it through a wire size calculator online and that's what it kicked out. Maybe I'm missing something?

Last question since you were so knowledgeable about wire size. I'm using two of these batteries...12v 100ah

https://smile.amazon.com/gp/product/B08FMTRYPT/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The website says the can be wired together using 4awg. But nothing I read showed that as enough so I was going to step up to 2 or even 2/0awg as some wire size calculators have said. any sources of information I should look to to help determine the largest size wire I would need for a system with two of those in parallel? I'd use that for the batteries, run to the switches and bus bars, shunt, as well as the chassis ground.

 

[John Frum]

Thank you for catching that. This is what the specs say: Max Amps: 100A per block, 30A per circuit.

https://smile.amazon.com/gp/product/B001P6FTHC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I was thinking that if I had say, three of the circuits each pulling 30a then I might get 90a or more into the block itself and needed the bigger wire. Realistically I'm not going to be close to 100a through the block so I can probably downside but I was attempting to allow room to scale up if I did need the extra power. Am I thinking about that right when I read the specs at 100a per block?

Yes the max aggregate fault current for the fuse block is 100 amps.
The max fault current for each branch circuit is 30 amps.
Beefing up one of the branch circuits won't do much to help the fuse block as a whole.
Fun fact... since the max fuse size for a branch circuit is 30 amps that means the max continous current on that circuit should be no higher than 24 amps.

I'm trying to account for voltage drop and making sure there's as little as possible between the battery and the fridge. It's about 25ft of wire one way unfortunately.

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

The input data points are system voltage, round trip circuit length and amps.
The only thing I don't know is amps.
If you want to keep the voltage drop to a minimum you can terminate this circuit on the core busbars instead of the fuse block.
8 awg is no problem in that case.

Last question since you were so knowledgeable about wire size. I'm using two of these batteries...12v 100ah

https://smile.amazon.com/gp/product/B08FMTRYPT/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The website says the can be wired together using 4awg.

Those can be wired to the busbars individually with 4 awg.
If you want to parallel the batteries before they get to the busbar then you need wire for twice the current.
Each of those batteries can deliver 100 amps continuous.
100 amps * 2 batteries = 200 service amps.
200 service amps / .8 fuse headroom = 250 fault amps.
That means 1/0 awg wire with a 250 amp fuse for the pair.
Or 4 awg wires with 150 amp fuses per battery.

To figure the wire and fuse for your inverter....
1000 ac watts / .85 conversion factor / 10 volts low cutoff = 117.647058824 service amps
117.647058824 service amps / .8 fuse headroom = 147.058823529 fault amps
That means you could use 4 awg with a 150 amp fuse.
But that is really close to the edge so I would use 2 awg wire with a 200 amp fuse.

But nothing I read showed that as enough so I was going to step up to 2 or even 2/0awg as some wire size calculators have said. any sources of information I should look to to help determine the largest size wire I would need for a system with two of those in parallel? I'd use that for the batteries, run to the switches and bus bars, shunt, as well as the chassis ground.

See in-line response above ^

 

[dsaint1884]

Yes the max aggregate fault current for the fuse block is 100 amps.
The max fault current for each branch circuit is 30 amps.
Beefing up one of the branch circuits won't do much to help the fuse block as a whole.
Fun fact... since the max fuse size for a branch circuit is 30 amps that means the max continous current on that circuit should be no higher than 24 amps.

So if each branch will have it's own fuse at 30amps or less within the box, and if the max aggregate current is 100amps shouldn't I size the fuse for the block as a whole accordingly? I'm not trying to beef up a specific branch with a large fuse, but trying to protect the box from the aggregate current of all the branch's that may be running - max at 100a as the block limit. Each branch has it's own fuse as well.

The fridge is a 60w fridge running 13v dc. So around 5a. Which using the calculator you provided means I could get away with 10awg. I already have the 8awg so if I can get it on the fuse block I may stick with it.

Aside from that, thank you for all of the help and input. It's really great insight for me. I guess the wire gauge and fuse size on the inverter were closer to being right than I thought but I got there for the wrong reasons.

Thanks you!

 

[John Frum]

So if each branch will have it's own fuse at 30amps or less within the box, and if the max aggregate current is 100amps shouldn't I size the fuse for the block as a whole accordingly?

Are you talking about the fuse for the feeder?
If yes, then yes.
6 awg with a 100 amp fuse for the feeder.

I'm not trying to beef up a specific branch with a large fuse, but trying to protect the box from the aggregate current of all the branch's that may be running - max at 100a as the block limit. Each branch has it's own fuse as well.

See above.
The Fridge is on a branch circuit, not the feeder.

The fridge is a 60w fridge running 13v dc. So around 5a.

5 amps over 50 feet at 12 volts will give you ~2.16% voltage drop which is fine.

Aside from that, thank you for all of the help and input.

Aside from that you are welcome.

 

[HRTKD]

Do I need a fuse here? I was under the impression that my 2s2p setup can't exceed the wire capacity or what the MPPT should be able to handle. I'll be switching to a dual pole breaker, but the amps are so high it wouldn't provide any current protection, just disconnect.

https://www.amazon.com/dp/B096315TSJ?psc=1&ref=ppx_yo2ov_dt_b_product_details

No, a fuse between the strings isn't necessary. If you had 3P then fuses would be required.

The 63 amp breaker is too much, so select the smaller 25 amp breaker on that same page. We're mainly using it as a switch with over current protection as minor bonus.

Gotch ya, I was putting a fuse on for the peak surge capacity of the inverter which is 2000w. I went with 1.25x, you scaled down for inverter efficiency. Should I be using the 66amps or 2000 surge watts x .85 / 12.8v getting to 130amps? Either way, the 200 is too large, ty.

https://amazon.com/gp/product/B07JMQ27WJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Surge should be a momentary occurrence. For some inverters, that's less than a second. So we usually don't fuse for peak, rather continuous.

If you know you'll never draw more than 500 watts then you might size the fuse for that. On my system I have 560 Ah of batteries that can produce up to 240 amps continuous. I won't pull that much at any one time so I have a 225 amp Class T fuse immediately downstream of my batteries.

I'm using these for bus bar and switch, both 250a or higher, and I have a 250a fuse coming off the battery so that's the max the system should be able to see:

Bus Bar - 250a

https://smile.amazon.com/gp/product/B07THLYYH3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Switch - 350a

https://smile.amazon.com/gp/product/B000MMC914/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Those aren't great bus bars. They are brass which has a higher resistance than copper.

The switch is great! I have that same one. You can't go wrong with Blue Sea Systems components. They're expensive, but very high quality.

 

[dsaint1884]

No, a fuse between the strings isn't necessary. If you had 3P then fuses would be required.

The 63 amp breaker is too much, so select the smaller 25 amp breaker on that same page. We're mainly using it as a switch with over current protection as minor bonus.

Surge should be a momentary occurrence. For some inverters, that's less than a second. So we usually don't fuse for peak, rather continuous.

If you know you'll never draw more than 500 watts then you might size the fuse for that. On my system I have 560 Ah of batteries that can produce up to 240 amps continuous. I won't pull that much at any one time so I have a 225 amp Class T fuse immediately downstream of my batteries.

Those aren't great bus bars. They are brass which has a higher resistance than copper.

The switch is great! I have that same one. You can't go wrong with Blue Sea Systems components. They're expensive, but very high quality.

Thank you for all of that, super helpful. I'll make some changes to the line-up. Thanks!