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Help with first wiring diagram

Scycle

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I want to start with a small system in my 50A 5th wheel with the possibility of expansion. I don't know if up-sizing fuses and wire now is best or just wires because I can change a breaker or put larger fuse in the older if rated for it. Not sure if they are sized correct to begin with.
 

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Your fuse is waaay over sized for that system. The fuse is there to protect the wires, so with a 1Kw inverter you'll want to calculate your DC12v max loads + the inverter (1000w/12v=84a) and multiply that by 1.25 for your final fuse rating. You don't want your fuse so oversized that it just sits there happily humming along while your wires are on fire.

Also with LFP, make sure you use a Class-T fuse and holder.

Oversizing the wires now though is a good idea if you're planning on upgrading in the future. As you mentioned it's easy enough to put a larger fuse in the holder later.
 
Using 2/0 marine grade cable, the 250 ampere fuse is acceptable. I would maybe use a 300A. There needs be another fuse where the cable changes to a smaller gauge. Like the 6 awg to the RV PWR DIST. 120 ampere max fuse.
The 2/0 is maybe too large gauge for the inverter/mppt/etc. Larger doesn't hurt, but you can save some cost. Do a voltage drop calculation to select the proper gauge cables.
 
Your fuse is waaay over sized for that system. The fuse is there to protect the wires, so with a 1Kw inverter you'll want to calculate your DC12v max loads + the inverter (1000w/12v=84a) and multiply that by 1.25 for your final fuse rating. You don't want your fuse so oversized that it just sits there happily humming along while your wires are on fire.

Also with LFP, make sure you use a Class-T fuse and holder.

Oversizing the wires now though is a good idea if you're planning on upgrading in the future. As you mentioned it's easy enough to put a larger fuse in the holder later.
Are you saying I'm at 84a just for the inverter then I add 12v loads and multiply by 1.25?
Are you referring to the "T" fuse at the batteries?
I did change the battery disconnect to the negative line, I read several people do that. I also read something about adding a 50a breaker (recommended by MPP) to the AC input side of the unit.
Right now I'm only using 6,10 and 2/0 awg wire, but thought about changing the 2/0 to 4/0 for possible expansion, but I doubt if I would ever have more than 600w of solar, more like 400w.
 

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Are you saying I'm at 84a just for the inverter then I add 12v loads and multiply by 1.25?
Exactly. So, as an example, if you had your inverter (1000w/12v=84a) and a propane heater (60w/12v=5a) and 5 small lights (6w ea/12v = .5a * 6 lights = 3a) you would add the amps up all together (84+5+3=92a) and multiply by 25% extra surge/headroom (92a * 1.25 = 115a) and you'll likely get a number that doesn't exist in fuses. In this example you'd round that 115a up to a 125a fuse.

Are you referring to the "T" fuse at the batteries?
Yes, it's a style of fuse called Class-T and it's the safest option for protecting your system with LFP batteries.

I did change the battery disconnect to the negative line, I read several people do that. I also read something about adding a 50a breaker (recommended by MPP) to the AC input side of the unit.
Yup, that works fine.

Right now I'm only using 6,10 and 2/0 awg wire, but thought about changing the 2/0 to 4/0 for possible expansion, but I doubt if I would ever have more than 600w of solar, more like 400w.
Better to plan for 600w of solar than have 400w and have to re-run all your wire later. :) The biggest ones you need to worry about are the wires from the battery to the inverter and the SCC to the battery since those are the major load carrying ones and are where the expensive wire really starts to add up.

Looking really good!
 
Do ever expect to have more than 300 ampere draw or charge current?
2/0 marine grade cable, 300 amp Class-T fuse at positive battery terminal. Class-T fuse requires a holder. So, short cable to fuse holder then longer cable to BusBar. Take note, Class-T dc fuses come in two physical sizes.
I would fuse easc branch circuit at the BusBar. Especially required if the wire gauge is smaller.
 
Exactly. So, as an example, if you had your inverter (1000w/12v=84a) and a propane heater (60w/12v=5a) and 5 small lights (6w ea/12v = .5a * 6 lights = 3a) you would add the amps up all together (84+5+3=92a) and multiply by 25% extra surge/headroom (92a * 1.25 = 115a) and you'll likely get a number that doesn't exist in fuses. In this example you'd round that 115a up to a 125a fuse.
If I plan for future expansion looking at the multiplus II because it has two AC 120v lines out and that has a 3000w inverter (3000w/12v=250a) and estimate 150w camper use (150w/12v=13a) so 263a*1.25=329a so 350a. Current system would be 84a+13a=97a or 100a, big difference. I haven't seen a chart listing 350a for cable just 260a with 4/0.
Yes, it's a style of fuse called Class-T and it's the safest option for protecting your system with LFP batteries.


Yup, that works fine.


Better to plan for 600w of solar than have 400w and have to re-run all your wire later. :) The biggest ones you need to worry about are the wires from the battery to the inverter and the SCC to the battery since those are the major load carrying ones and are where the expensive wire really starts to add up.

Looking really good!
 
Do ever expect to have more than 300 ampere draw or charge current?
2/0 marine grade cable, 300 amp Class-T fuse at positive battery terminal. Class-T fuse requires a holder. So, short cable to fuse holder then longer cable to BusBar. Take note, Class-T dc fuses come in two physical sizes.
I would fuse easc branch circuit at the BusBar. Especially required if the wire gauge is smaller.
Possibly if I go with the future plan using the multiplus II as calculated in my post to rednecktek. I do plan on fusing at the lynx, just haven't determined the correct size yet.
 
Your fuse is waaay over sized for that system. The fuse is there to protect the wires
The OP shows 2/0 wire. A 250A fuse on 2/0 is just fine. The 2/0 is good for up to 200A of loads.

This system can have up to 100A for the 1000W 12V inverter and an unknown amount of loads for the DC fuse box. Since that is wired with 6AWG the DC loads could be up to 70A. So it's possible there could be 170A of loads being pulled from the battery. Given that, the 2/0AWG wire and 250A fuse is just fine.
 
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If I plan for future expansion looking at the multiplus II because it has two AC 120v lines out and that has a 3000w inverter (3000w/12v=250a) and estimate 150w camper use (150w/12v=13a) so 263a*1.25=329a so 350a. Current system would be 84a+13a=97a or 100a, big difference. I haven't seen a chart listing 350a for cable just 260a with 4/0.
This is a little off. A 3000W 12V inverter can result in up to 3000W / 12V / 85% efficiency = 300A draw from the battery. Add the 13A DC loads and you are up to 313A from the battery. That requires 4/0AWG wire. For the fuse you have 313A x 125% = 391A so you need a 400A fuse. 4/0AWG is safe to fuse at 400A.
 
If you go to 3000W inverter, I suggest you upgrade to 24 volts.
All the wire i use and design is marine grade tinned copper stranded wire. The leading manufacturers are Anchor and EPM Marine Master.
This 2/0 cable will safely carry 330 amperes. If 4/0, safely carry 445 amperes. Anything over 300 amperes is a lot of continuous dc current.
The proper consideration to select the cable gauge is a voltage drop table. That takes length, maximum expected amperes and voltage.
 
I updated the drawing wire gauge, fuses and a 50a breaker on the AC input line to the inverter as mfg recommended. Anyone know of a more compact design for a 50A single pole breaker box?
 

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