Battery Bank to AIO (Question)

[AtomicLowe]

From Will's (exceedingly helpful) video and related materials I'm observing:

4/0 Cu from Rack =>
300A Busbar =>
200A T-Class Fuse =>
2/0 Cu Inverter Supply (Noted as "required")

I'm totally new at this, but I can't lurk my way to understanding so...

1) Given the fuse amperage at 200A, is the 300A busbar overfit?
2) Given the 2/0 Cu Inverter Supply, is the 4/0 Cu from Rack to busbar overfit, or is this to accommodate drop due to the run length?
3) Is the 2/0 Cu Inverter Supply required because that's what fits, or required to accommodate current?

Despite my questions, I'm not disagreeing with anything. I'm not qualified to.

I'm just trying to gain a functional understanding.

 

[Dave in AZ]

Just looking at the picture, not rereading his system:
2 separate batteries, battery1 is obviously larger as requires 4/0. Battery2 smaller, needs 2/0 only. Batteries combine at busbars, so that needs to be bigger to handle both battery amps, so 300A bus. The amps then SPLIT to two inverters, so half goes to each. So say 150Amps each, thus protected by a 200map T fuse. Because the total amps split, which we know is less than 300 because that is max on busbars, you can go back to 2/0 wire that can do 200A each.

Nothing is EVER because that is what fits! Every wire and component must be correctly sized to carry the load it will see, and the fuses to protect the wires in case of overload. The T fuses are required on the positive power line, because they are super fast, and can keep the Eg4s from melting if overcurrent, wheareas ANL fuses sometimes seen elsewhere may not be fast enough.
Here, always reference a wire sizing chart per amps carried, while looking at these setups. Reread Will's writeup or video where he talks about sizing wires and fuses, usually 1.25 x the wire. So fuse blows quickly before wire melts.

Maybe think of each battery and wire as a hose, you can then imagine how 2 hoses combining at busbar needs a bigger 300A hose, then it splits the flow, so only half as big a hose is needed to the EG4s. I believe if you were thinking of it this way, you wouldn't ask about the sizes. Nothing wrong with asking, just better if YOU understand it enough to not have to ask keeps mistakes down.
Good luck!

 

[AtomicLowe]

Just looking at the picture, not rereading his system:
2 separate batteries, battery1 is obviously larger as requires 4/0. Battery2 smaller, needs 2/0 only. Batteries combine at busbars, so that needs to be bigger to handle both battery amps, so 300A bus. The amps then SPLIT to two inverters, so half goes to each. So say 150Amps each, thus protected by a 200map T fuse. Because the total amps split, which we know is less than 300 because that is max on busbars, you can go back to 2/0 wire that can do 200A each.

Nothing is EVER because that is what fits! Every wire and component must be correctly sized to carry the load it will see, and the fuses to protect the wires in case of overload. The T fuses are required on the positive power line, because they are super fast, and can keep the Eg4s from melting if overcurrent, wheareas ANL fuses sometimes seen elsewhere may not be fast enough.
Here, always reference a wire sizing chart per amps carried, while looking at these setups. Reread Will's writeup or video where he talks about sizing wires and fuses, usually 1.25 x the wire. So fuse blows quickly before wire melts.

Maybe think of each battery and wire as a hose, you can then imagine how 2 hoses combining at busbar needs a bigger 300A hose, then it splits the flow, so only half as big a hose is needed to the EG4s. I believe if you were thinking of it this way, you wouldn't ask about the sizes. Nothing wrong with asking, just better if YOU understand it enough to not have to ask keeps mistakes down.
Good luck!

View attachment 184418

Great chart, thanks!