Fuse size: 30ah lifepo4 <-> 600w 12v inverter

[solarstuff]

Hi all, my eco-worthy lifepo4 30ah has a BMS with a max charge of 20A, discharge of 25.
Does that mean I don't need to fuse to my Giandel 12v inverter?
It's rated to 600w & Will says it's a 60A input.

 

[rodrick]

Don’t rely on the bms for primary protection fuse your wiring to protect it

 

[MisterSandals]

my Giandel 12v inverter?
It's rated to 600w & Will says it's a 60A input.

600W / 10V inverter cutoff / .85 efficiency = 70.6A potential draw

25A discharge limit x 10V cutoff / .85 efficiency = 294W max load plugged into inverter before BMS "should" trip (bad)

 

[solarstuff]

600W / 10V inverter cutoff / .85 efficiency = 70.6A potential draw

25A discharge limit x 10V cutoff / .85 efficiency = 294W max load plugged into inverter before BMS "should" trip (bad)

Should I adda 30a breaker to gatekeep, if I don't expect large loads?

 

[MisterSandals]

Should I adda 30a breaker to gatekeep, if I don't expect large loads?

If it were me, i'd gatekeep to protect the BMS. Is a 20A breaker/fuse to limiting on your power needs? 25A max but not sure if breaker or BMS would be first line of defense. BMSs are a lot more fragile and expensive than breakers.

 

[solarstuff]

If it were me, i'd gatekeep to protect the BMS. Is a 20A breaker/fuse to limiting on your power needs? 25A max but not sure if breaker or BMS would be first line of defense. BMSs are a lot more fragile and expensive than breakers.

Good plan. I agree. I may have tonchabge my charger though.l Will a 20a breaker trip with a 20a charger?

 

[MisterSandals]

l Will a 20a breaker trip with a 20a charger?

Not sure if BMS or breaker would trip first. Its a small battery any you are dealing with the manufacturer amp limits.

 

[solarstuff]

Not sure if BMS or breaker would trip first. Its a small battery any you are dealing with the manufacturer amp limits.

Dumb question: will two batteries with 25a discharge bms's paired give me overhead to use a 35a or 40a breaker/fuse?

 

[MisterSandals]

Yes if connected in parallel in a balanced manner.

 

[solarstuff]

Yes if connected in parallel in a balanced manner.

OK thanks MisterS, I may consider paralleling a second matching battery BUT in the meantime, the official specs say max charge/discharge are both 30a so a 25a breaker gives me enough headroom for a 20a charger, right?

 

[MisterSandals]

specs say max charge/discharge are both 30a so a 25a breaker gives me enough headroom for a 20a charger, right?

Well a 20A charger will never charge more than 20A so yes.