Seeking Clarity

[Victoryrider]

Looking for some clarity, I know there are people out there that understand this stuff much better than I do.
I am installing a solar system on my RV, I have the solar side figured out, but am confused with the Inverter/charger and battery side.

I am installing a 3000W inverter charger in a 12V system with 4x parallel 100Ah Lifepo4 lithium batteries. I have determined that the system will generate 250A (3000/12 = 250) calculating the fuse requirements 250 x 125% = 312.5A rounding up to 350A fuse requirement.

According to the specs the Lifepo4 BMS allowable maximum output current in 100A. My understanding is when batteries are connected in parallel the voltage remains the same and the current adds, so my 4x Lifepo4 batteries will create a 12V system at 400 Amps. I am using 4/0 wire (short as practical connections) for the batteries and inverter connections. I intend on fusing each battery and the overall feed to the Inverter/Charger (I know overkill, but a few bucks of extra safety).

My confusion: considering the BMS will limit output current to 100A:
Will the overall current in the parallel system be limited to 100A (due to the BMS output restriction of 100A from each battery)? Or will the BMS limit each battery to 100A output and the amperage still accumulates to 400A?
Do I fuse each battery at 100A and 400A overall?
Or
Do I fuse the batteries at 400A (cumulative 100A) and 400A overall?
Or
Since the max draw of the Inverter will be 250A considering the 125% safety factor do I fuse the system to 350A (rounding up)?

My understanding now is, I fuse the batteries at 100A (in case the BMS craps out) and fuse the overall system at 350A (to protect the inverter), or am I right out to lunch?

The more I research this aspect the more confused I am becoming.

Thanks in advance,

Dez

 

[rhino]

Will the overall current in the parallel system be limited to 100A (due to the BMS output restriction of 100A from each battery)? Or will the BMS limit each battery to 100A output and the amperage still accumulates to 400A?

400A, they are in parallel so each can contribute it's max.

Do I fuse each battery at 100A and 400A overall?
Or
Do I fuse the batteries at 400A (cumulative 100A) and 400A overall?
Or
Since the max draw of the Inverter will be 250A considering the 125% safety factor do I fuse the system to 350A (rounding up)?

Not clear what exactly you are asking but you would fuse for each battery at the rating for that battery alone and then you can have a larger fuse for the entire system. Assuming your max continuous output would be 320A then a 400A for the main cable would be fine (320 since that is what the maximum 400A fuse should run continuously at).