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Adding a second serial pair of batteries to my Serial/Parallel battery array. Wire gauge increase?

jellystanchina

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Dec 3, 2020
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Current battery configuration
2 - 12 volt, 100 amp, 1200 watt, LiFePO4 Deep Cycle
- 1 pair of batteries wired serial together (volt x 2)
- Pair Array Output: 24 volts, 100 amp, 2400 watt
- Wire gauge (Up to 6 Feet): 4 AWG

1607019713125.png


If I add a second serial pair, in parallel...
Do I need to increase my wire gauge based on total amperage?
Or do I stay with the wire gauge based on a a single series pair?

1607019676561.png

Thanks in advance,
Jelly
 
Dear Jelly,

What kind of continuous watts loads on inverter?

My reaction is that increasing wire gauge might be justifiable depending on usage/discharge.
 
Dear Jelly,

What kind of continuous watts loads on inverter?

My reaction is that increasing wire gauge might be justifiable depending on usage/discharge.
No loads yet.
Building the prototype setup in the garage first.
Then plan on a transplant into my 26" travel trailer.

Following the Will Prowse 24 volt setup
 
Wire gauge would be based on continuous current draw by inverter. That doesn't change when you add batteries.
(Actually, fuse should be sized 125% of max continuous draw. Wire should be sized large enough for fuse, or larger.)

Is that a 2400W inverter? Due to inefficiency, will draw more than 100A from 24V. Due to voltage dipping below 24V, will draw more.
Compute using low voltage disconnect, and inverter efficiency at full load.

You might make wire even larger for reduced IR drop of longer runs.
4 awg is relatively thin, even if OK per calculations. I would bump it up to 2/0 or largest that fits in terminals.
 
Wire gauge would be based on continuous current draw by inverter. That doesn't change when you add batteries.
(Actually, fuse should be sized 125% of max continuous draw. Wire should be sized large enough for fuse, or larger.)

Is that a 2400W inverter? Due to inefficiency, will draw more than 100A from 24V. Due to voltage dipping below 24V, will draw more.
Compute using low voltage disconnect, and inverter efficiency at full load.

You might make wire even larger for reduced IR drop of longer runs.
4 awg is relatively thin, even if OK per calculations. I would bump it up to 2/0 or largest that fits in terminals.
Hedges,

You totally just mirrored the advise of my housemate :)
Makes sense and sounds great.
Now to make some measurements for a big fat 2|0 wire purchase
 
Current battery configuration
2 - 12 volt, 100 amp, 1200 watt, LiFePO4 Deep Cycle
- 1 pair of batteries wired serial together (volt x 2)
- Pair Array Output: 24 volts, 100 amp, 2400 watt
- Wire gauge (Up to 6 Feet): 4 AWG

View attachment 29225


If I add a second serial pair, in parallel...
Do I need to increase my wire gauge based on total amperage?
Or do I stay with the wire gauge based on a a single series pair?

View attachment 29224

Thanks in advance,
Jelly
I think the cable gauge will be ok, as you are only taking half the amps now from two branches now, instead of all from 1 branch.
As long as your inverter is not over 2000w, rest of wire at 4AWG should be ok. if going over 100A current upgrade to 2AWG.
cheers
Brian
 
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