Should I put a circuit breaker between inverter and BMS?

st4rgut
st4rgut Registered Users Posts: 36 ✭✭
edited May 2021 in Off Grid Solar & Battery Systems #1
Hi all, I have a common port Daly BMS I bought cheap off ebay, and am wondering if I should have a circuit breaker between the BMS and inverter. On several occasions the 150A rated circuit breaker has tripped, knocking my inverter offline. I usually have to replug the balance ledes of the BMS to start the inverter again. I'm wondering whether this is a case of nuisance tripping since my BMS supposedly has some temperature protection. I know 150A sounds excessive, but I'm almost certain it's less current than that (the BMS is rated for 60A so if it were over 60A wouldn't the BMS shut down before the circuit breaker opens?) Furthermore, my load is 50A at the highest. Another thing I've noticed is the BMS is very warm when the breaker opens, though not too hot to touch. Anyway, I'm just wondering if it would be worth risking the BMS / batteries to ditch the circuit breaker between the inverter and BMS. Any input is much appreciated.

=====EDIT======
I just realized my circuit breaker is rated 12V and my pack is 48V, which could be the reason for the nuisance tripping. Confirmation is appreciated.
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  • KenMorgan
    KenMorgan Registered Users Posts: 92 ✭✭
    #2
    yes the issue is a 12 vote rated circuit breaker on a 48 volt circuit.  I would advise getting a T class fuse in the 100 amp range and then install a separate disconnect.  the breaker probably cannot handle much more than 40 amps continuously but even then the chance of it arcing over internally and burning the contacts is high. 
    70kw LiFePo4 battery bank, 18 JA solar 200 watt panels, 20 sharp 200 watt panels,  morningstar controller(s) and a magnum 4448 inverter with all the usual junk that goes with it. 
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