Please verify my LiFePo4 system

Hi,
I am buidling 2x200ah batteries with Seplos BMS and will be connecting them to 5kW Hybrid inverter. The inverter can max charge/discharge at 62A. I already have Schneider DC breaker connected as it was used with Pylon batteries and intend to leave it there. The wires are 16mm2(6AWG). Since there will be 2 separate batteries I will use busbars and then 100A fuses. I am still not sure should I go wih ANL or NH00. I know recomended are class T fuses but the current is not going to be high.
Here are my questions:
Could I potentialy use DC breakers instead of fuses?
I am reading that the fuses should be close to battery. At the moment the fuse is before BMS. Should I move it between BMS and the battery?
Does attached diagram look ok?
Thanks

Does the seplos BMS include current accounting?
I ask because I don't see a shunt.
Since we don't know the wire guages we can't verify the fusing.
Why are you using a double pole breaker in front of the inverter/charger?

The positive lead probably doesn't go through the bms, confirm?

smoothJoey said:

Does the seplos BMS include current accounting?
I ask because I don't see a shunt.
Since we don't know the wire guages we can't verify the fusing.
Why are you using a double pole breaker in front of the inverter/charger?

The positive lead probably doesn't go through the bms, confirm?

Click to expand...

Double pole breaker was installed originally by PV installer
Seplos has shunt and both positive and negative go through seplos. Wires are 6AWG

reklamos said:

Double pole breaker was installed originally by PV installer
Seplos has shunt and both positive and negative go through seplos. Wires are 6AWG

Click to expand...

6 awg with 105C insulation is rated for 120 fault amps.

5kW / 48V / 0.85 = 123A. The inverter needs to be wired to handle 123A. That requires at least 35mm² wire (between 2AWG and 1AWG). You need a 150A - 175A fuse to the inverter.

reklamos said:

I know recomended are class T fuses but the current is not going to be high.

Click to expand...

It's not the normal current you need to worry about (other than sizing the wire and fuse correctly). It's the vastly higher amounts that LiFePO₄ can dump out in a failure condition. That is why Class T fuses are recommended with LiFePO₄, especially for 48V.

rmaddy said:

5kW / 48V / 0.85 = 123A. The inverter needs to be wired to handle 123A. That requires at least 35mm² wire (between 2AWG and 1AWG). You need a 150A - 175A fuse to the inverter.


It's not the normal current you need to worry about (other than sizing the wire and fuse correctly). It's the vastly higher amounts that LiFePO₄ can dump out in a failure condition. That is why Class T fuses are recommended with LiFePO₄, especially for 48V.

Click to expand...

Although inverter is 5kW the max charge/discharge of inverter 3kW do I still require 35mm² wire?

reklamos said:

Although inverter is 5kW the max charge/discharge of inverter 3kW do I still require 35mm² wire?

Click to expand...

I don't understand what you mean. Why is it called a 5kW inverter if it can only provide 3kW from the battery?

How about a link to ID the "inverter" you have.

This is nothing special, many hybrid inverters cannot charge at full power. See manual attached, page 54

I am surprised there is no instruction on connecting the dc battery. There is a mention in a table of maximum discharge of the battery. 62.5 ampere.
If the positive cable to the BMS is short enough you have the fuses in the right location. If there is danger of a short circuit before the BMS, I would fuse at the battery terminal. That seems a nice BMS. It is the first I have seen with positive dc circuit control. Just remember fuses protect wires. I would figure the maximum battery ampere at 70 or 75 amperes. Calculate the wire gauge by voltage drop at the length of the cable, your 48 volts and 75 amperes. Use the ampacity of that gauge wire to select the proper sized fuse. Use quality dc fuses such as Class-T from Blue Sea. Fuses don't control current, they protect wires.