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doubling up on battery bank cables

4/0 awg to fuse & inverter.
1 awg all around bank.
IMG_20200926_211010.jpg
Don't think you have any need. Sketch out a wiring diagram that matches physical implementation (something equivalent to that battery wiring picture I plagiarized) and we can check it out. Label which awg where.
 
4/0 awg to fuse & inverter.
1 awg all around bank.

Inverter wired to corners. 4/0 takes 100%, 1 awg takes 75%, 1 awg takes 50%, 1 awg takes 25%
No need to make any wires larger.
You could add two more 1 awg cables and change wiring so all batteries get exactly same cable length in series. That will better match discharge across all four batteries, especially at higher current. It will also reduce highest current in 1 awg to 50%
 
Thanks.I like the idea of more evenly distributing energy and 'wear'.

Does this cable arrangement maintain the bank as 12v & 400ah?

Inverter wired to corners. 4/0 takes 100%, 1 awg takes 75%, 1 awg takes 50%, 1 awg takes 25%
No need to make any wires larger.
You could add two more 1 awg cables and change wiring so all batteries get exactly same cable length in series. That will better match discharge across all four batteries, especially at higher current. It will also reduce highest current in 1 awg to 50%
 
Doubling up on wiring and fusing confuse me. If the fuse for the wire size is 200 amps, do you half that for each wire, or do you go with a 200 amp fuse on each wire?

My gut tells me if both wires are the same its 100. If the wires are different its probably ratios and proportions.
 
Thanks.I like the idea of more evenly distributing energy and 'wear'.

Does this cable arrangement maintain the bank as 12v & 400ah?

Yes, if it was four, 12V 100ah in parallel before, this is still four in parallel. It just added extra wire length so every battery has exactly one short 1 awg carrying 25% and one long awg carrying 50% of total inverter current.
 
Doubling up on wiring and fusing confuse me. If the fuse for the wire size is 200 amps, do you half that for each wire, or do you go with a 200 amp fuse on each wire?

My gut tells me if both wires are the same its 100. If the wires are different its probably ratios and proportions.

This setup is less than perfect because if two batteries were open circuited, all current from the fuse would go through a single 1 awg wire. Multiple fuses could protect the branches.
If there is a dead short, 1 awg won't have any trouble blowing the fuse because it'll happen before the wire gets warm.
The inverter can't carry enough current to blow the fuse or to overheat the wire in normal operation.
If transistors melt and start smoking, might be able to introduce enough resistance to limit current so fuse doesn't blow but wire overheats.
 
Help!
I've done as advised in this thread, changed my cables to equalize the load on all 4 of my 100a AGM batteries.

But it's now shorting when I attempt to connect the circuit.

I need a fresh set of eyes.

Have removed the positive from inverter to the circuit breaker but otherwise this is exactly the config I had when I attempted to connect my negative directly to my battery bank in the new config.

IMG_20200929_140821.jpg
 
Shorting is bad!

The red, blue, and fat black look OK, at least not shorting (not sure about length balance with not all connected.)
But there is a skinny black I can't make out.

How about sketching a schematic?
 
All looks fine.

With 4/0 disconnected, the 1 awg just connect all positive in parallel, and all negative in parallel.
The 4/0 look correct, unless far end is now shorted.
You have other wires connected to battery in photo, not shown in drawing.

Sure that was a short, not just charging a capacitor?
Use a volt meter between wire and terminal you're going to connect, make sure no voltage present.
If charging a capacitor, it will show voltage initially but bleed off as cap charges through (10 Meg or whatever) meter impedance.

With 250A breaker off, shouldn't even have to charge a cap to get zero volts to confirm no short before connecting.
 
If your batteries are in parallel, the wires between them carry less so no need for larger wires.
But you should design the interconnect scheme so all get exactly matched IR drop, charge and discharge identically.

Something like this:

View attachment 23763
Very late entry on this but in the schematic, two of the battery wires are longer that the other four. Is that just a result of the drawing, and they're actually all matched in length? Or is there a length difference? (I suspect not.)
 
Very late entry on this but in the schematic, two of the battery wires are longer that the other four. Is that just a result of the drawing, and they're actually all matched in length? Or is there a length difference? (I suspect not.)

The two are allowed to be longer than the four. They just have to be matched to each other. They could be matched to the four, but that would make the four longer than necessary.

If you trace out the path from each battery to load, each has exactly the same total path. Each matched wire has exactly the same current as others of that length. So it should be perfectly balanced.
 
If your batteries are in parallel, the wires between them carry less so no need for larger wires.
But you should design the interconnect scheme so all get exactly matched IR drop, charge and discharge identically.

Something like this:

View attachment 23763
What is the configuration of one only has 3 batteries instead of four?

Thank you.
 
Maybe 3 cables to a busbar would be close enough.
Or stack 3 cables on a stud (e.g. fuse holder), and stack the negative cables in the other order.

I have a similar issue for 3 inverters (with AC connected for 3-phase). In that case, 1 battery 3 inverters, matching resistance isn't really important. I just want low resistance connections. My fuse holders have only two set-screw connectors. Maybe I'll use a tall set screw ("grub screw") and add a nut for the 3rd cable.
 
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