MPP All-in-One Fuse

[mim]

Hi there! I bought the MPP 12v 1kva model with the 800watt inverter all-in-one kit and I'm ready to get it set up finally, however I'm having a hard time figuring out what fuse I need for the positive wire that goes directly into my 12v battery. There isn't a suggestion in the manual either. I'll have 4x100watt solar panels on the roof. Will mentioned needing a few to a sealed lead acid battery in his video here:

but I'm a little lost since I'm so new to this. Also would a 4 AWG wire be enough?

Thanks for the help.

 

[tfish86]

I have the same question. I see in the manual that the max amp this unit draws is 109 amps. So my guess would be 109x1.25 = 136.25 rounded up to a 150 amp fuse(?) But I also want to know for sure as I am a newb with solar.

Will does not put a fuse on in the video above due to 'over current protection' of his battleborn. I have a SOK 12 200ah battery which also seems to have this protection, but I still would like to fuse it just in case.

 

[tfish86]

*mine is the 1000watt instead of the 800 watt inverter

 

[kingsling]

I Have same or similar questions?
In Will's Video he states no fuse is needed because the battery has a BMS of its own?
Will also shows no circuit breaker with the AC connection and the MPP Manual states that the unit is protected (see #11 item in description of manual layout)?
But then the manual states that a breaker/fuse should be installed ahead of the DC Positive and the AC input, in the connection/installation sections??
Its Christmas Time and I'm asking Santa or Will or Anyone,
PLEASE HELP!

 

[rodrick]

Amps x volts = watts if it is a 1000 watt on a 12 volt unit 1000/12=84 amps x 1.25=105 amps that would be under normal running if unit has a higher surge rating use that rating then size wire according to the amps

 

[12VoltInstalls]

having a hard time figuring out what fuse I need for the positive wire that goes directly into my 12v battery.

4 gage will “work” and is adequate for a short run but I’d use at least 2ga.

I have that same AIO with 1000W inverter and used 2/0ga myself. Because I also have a 2000W inverter and that’s still oversized for that.

The AIO case indeed has a fuse but I would tend to want to see a fuse at the source of power: the battery.

I haven’t installed my lithium’s yet, I am running the lead acids still. Which is fine.

But my 12V lithium batteries are rated at 100A discharge each so each of them have a 125A Class T fuse before their cables to the busbar. They are set up in series so the max they would ever see in normal use is ~80A on each cable if 2S or ~55A in 3S

The 125A fuse is there in case of a bad event: the cables are rated 200A+ so a 125A fuse will keep them from seeing a 10,000 amp discharge if something happens, stopping a likely fire hazard, and 125A fuses won’t blow at a 100A potential.

My opinion would be to advise you to use similar precautions.