Breaker size

[Mason0810]

How do I determine what size breaker to put between the battery and inverter? There are 24V, 32.5A from the battery and a 3500W 24V inverter. The website says 30A fuse for the inverter but I am assuming that this is for the built-in fuse.

 

[Rednecktek]

Watts / Volts * 1.25 = Fuse Size as a rule. So for your 3500w inverter @ 24v you're looking at (3500/24)*1.25= 182.3a. BUT since nobody makes a 182a fuse, you can round up to the next size which would be 200a.

The inverter's 30a fuse is for the 120v side, 3500w/120v= 29.16a, so 30a max draw on the AC end.

You're looking at a 4AWG at least if your wires are short.

 

[Mason0810]

Watts / Volts * 1.25 = Fuse Size as a rule. So for your 3500w inverter @ 24v you're looking at (3500/24)*1.25= 182.3a. BUT since nobody makes a 182a fuse, you can round up to the next size which would be 200a.

The inverter's 30a fuse is for the 120v side, 3500w/120v= 29.16a, so 30a max draw on the AC end.

You're looking at a 4AWG at least if your wires are short.

Thanks!

Like approximately how short?

 

[Zil]

Fuses are sized to the wire ampacity. Using the distance between battery and inverter 2 1/2 feet, total 5 feet of cable. 4 awg marine grade cable would be good size. That cable is good to 160 amperes. Closest fuse is 150 amperes.
If the distance is 5 feet, 10 feet cable round trip. You need 2 awg. But you can use a larger fuse, up to 200 ampere.

Circuit Wizard - Blue Sea Systems

 

[rmaddy]

I don't agree with the previous results.

3500W / 24V / 85% efficiency = 172A of loads. 172A x 1.25 = 215A fuse size.

For 172A loads you need at least 1/0AWG wire and that assumes high quality marine grade stranded pure copper wire with 105ºC rated insulation. 4AWG and even 2AWG are too small for 172A loads. This is based on the wire and fuse chart from Blue Sea Systems.