Fuse question

[Subdood]

I'm thinking of getting a couple 5kwh lifepo4 server rack batts for my 6500EX. Considering the most current the inverter will draw is about 148ADC (7.1kW/48VDC), would a 200A fuse between the battery bank and inverter be sufficient? I'd also use a 200A DC Nader breaker, so maybe a fuse is unnecessary?

Also, what about the wire size for that amount of current. Would 1/0 be good enough or should it be 2/0?

 

[MisterSandals]

inverter will draw is about 148ADC (7.1kW/48VDC),

7100W / 40V inverter cutoff / .85 efficiency = 208A (250A fuse)

Also, what about the wire size for that amount of current. Would 1/0 be good enough or should it be 2/0?

Depends in the wire length.

 

[Subdood]

7100W / 40V inverter cutoff / .85 efficiency = 208A (250A fuse)

Depends in the wire length.

I made my 7100W calc on about 90-92% efficiency of the inverter. Wouldn't the BMS shut off be above 40V, more like 45V?

The wire probably won't be more than 6-8ft.

Would I still need a fuse if there's a 200A DC breaker in there?

 

[MisterSandals]

Would I still need a fuse if there's a 200A DC breaker in there?

A class T is considered the safest. Folks use all kinds of different fuses and breakers. The fuse/breaker protects the wire so as long as your breaker trips before the wire catches fire its good.
The ease at which LiFePO4 can release a lot of amps so quickly, in a dead short for example, its thought that DC breakers are susceptible to welding themselves closed (bad, very bad).

 

[Subdood]

The ease at which LiFePO4 can release a lot of amps so quickly, in a dead short for example, its thought that DC breakers are susceptible to welding themselves closed (bad, very bad).

Good point, a fuse certainly wouldn't hurt. I had considered ANL fuses since they're cheaper, but not necessarily better than Class T.

 

[MisterSandals]

Good point, a fuse certainly wouldn't hurt. I had considered ANL fuses since they're cheaper, but not necessarily better than Class T.

I don't know the difference to be honest. I use breakers on my small batteries. I have 2 very big batteries in the making and will spend the $80 for class T and holder for each for safety.