Fuse for Victron 150/35 Output for 48V LFP System

[flammafeuer]

A vendor recommended a 58V 40A fuse for the Victron SmartSolar 150/35 output, but I was reading the manual/specification today, which stated that the equalization voltage can get to 64.8V. I haven't gotten an answer out of Victron or my local vendor, yet. What fuse should I be using on the output of this controller?

 

[Rocketman]

Really the voltage doesn’t matter much with fuses - it’s the amps to protect the wires.

With a mppt 150/35 - what wire are you using between the mppt and the bus bar/batteries?

If it is a 8awg wire - fuse it at 40amps and you will be fine. (Even if you put a 6awg wire 40a fuse would be fine or you could go 50a if you couldn’t find a 40a - with#6 wire).

A fuse is to protect the wire. If the 8awg wire rubbed through and shorted - the PV array can only ever put 35 amps into that short. BUT, the lithium batteries can put tens of thousands of amps into the short - (probably not with the bms’s & fuses - but the cells could). So you are protecting the wire with the fuse.

 

[flammafeuer]

Really the voltage doesn’t matter much with fuses - it’s the amps to protect the wires.

With a mppt 150/35 - what wire are you using between the mppt and the bus bar/batteries?

If it is a 8awg wire - fuse it at 40amps and you will be fine. (Even if you put a 6awg wire 40a fuse would be fine or you could go 50a if you couldn’t find a 40a - with#6 wire).

A fuse is to protect the wire. If the 8awg wire rubbed through and shorted - the PV array can only ever put 35 amps into that short. BUT, the lithium batteries can put tens of thousands of amps into the short - (probably not with the bms’s & fuses - but the cells could). So you are protecting the wire with the fuse.

Thanks. I'm using a 6AWG for the controller to bus bar (used a Blue Seas diagram to select). So, if I have 64V regularly hitting a fuse apparently rated for 58V, what happens? Does its performance degrade over time?