Confused about Fuses

[rogeri]

I have a small system, a 3000w/24v inverter with 2 24v liFePo4 batteries.

I am planning on adding a Blue Sea Systems 5191 Fuse Block Terminal (100amp) on each positive terminal and a Blue Sea Systems 5112 Fuse A3T/Class T 110A right after the terminal block. I already have a 160 Amp 2-Pole DC Circuit Breaker installed just before the inverter. If it matters, the cables from the batteries to the terminal blocks are 2 awg, while the cable from the terminal blocks to the inverter are 0/1 awg.

i am planning to move to a 5000w/48 volt system soon. Would this setup still work when the two 24 volt batteries are in series for the the 48 volt system?

Is this okay, overkill, or what? Thanks.

 

[rogeri]

Sorry, a quick correction. The Class T fuse will be larger for the current 24 volt system, and the cable is 1/0 awg.

 

[Suijkerbuijk]

Sorry, a quick correction. The Class T fuse will be larger for the current 24 volt system, and the cable is 1/0 awg.

Watts are watts.
So that inverter pull is about

5000watts : 48 volts = 104ampere
Than that same inverter can do small max of 10.000 watts
A t-fuse can break by that pull.
So you have to calculate that with it .
104x2 = 208ampere +10% overhead = 230a.
Only for the inverter
Than the rest u use from the battery if you use more than only the inverter it self
The cable have to handel that ampère 2.
Dont forget that

 

[rogeri]

Wow, 230 amp for the class T. Seems a little large? (I said I was confused?). I want to keep it fairly tight.

How about the 100 amp fuses on the terminal blocks? Or should they be larger? The batteries are protected by an internal BMS at 100 amps. Would it be the same is the batteries are in serial or parallel?

 

[OffGridForGood]

I have a small system, a 3000w/24v inverter with 2 24v liFePo4 batteries.

3000W /24v = 125A - typically we would assume some over-current for start up loads and want 150A available.
Fuses are to protect WIRES - so the wiring gauge and length / temperature ratings need to support more than the peak current.
Two parallel 100A batteries 24v can supply the above load with suitable wire ga. etc.

i am planning to move to a 5000w/48 volt system soon. Would this setup still work when the two 24 volt batteries are in series for the the 48 volt system?

Is this okay, overkill, or what? Thanks.

"Move to 48 volt" - implies you will series connect these same batteries - ie 100A limit. (I don't recommend series connecting LFP)
100A x 48 volt = 4800 W max. allowing 15-25% over-current you may be limited to about 4kW output on your inverter, depending on what loads you apply, and if they are motors (inductive loads).

For a 5kW 48 volt inverter, I would suggest 200A available supply current, supplied by actual 48v packs rather than series connected 24v.
Check the inverter installation manual, and it will likely also recommend a minimum available supply current for this unit.

 

[Suijkerbuijk]

Wow, 230 amp for the class T. Seems a little large? (I said I was confused?). I want to keep it fairly tight.

How about the 100 amp fuses on the terminal blocks? Or should they be larger? The batteries are protected by an internal BMS at 100 amps. Would it be the same is the batteries are in serial or parallel?

That is the problem with 48volts systeem.

With a 12/24 volts systeem you can go for the mrbf fuse .

But here special for you wy t-fuse is in use..