Battery cable length

[liberumyu]

Hello all.

I’m at stage of my project where I’m routing cables from inverters to battery bank.

My system has 3 inverters in parallel and I’m routing positive and negative from battery bank to busbars.

Now question is, should I have all cables from busbars to inverters same length or it doesn’t matter?

 

[time2roll]

The inverters don't need to have balanced connections. Each will draw or push what is needed.

Parallel batteries are a different story.

 

[liberumyu]

The inverters don't need to have balanced connections. Each will draw or push what is needed.

Parallel batteries are a different story.

Thank you very much.

Battery bank is paralleled in equal resistance manner but then I was wondering should this other part be done the same.

Thanks a lot, off I go cutting and crimping

 

[Steve_S]

Thank you very much.

Battery bank is paralleled in equal resistance manner but then I was wondering should this other part be done the same.

Thanks a lot, off I go cutting and crimping

I have always matched the lengths while taking into account space for Shunts etc.... I am Old School in that regards and believe that all things should be equal so that when troubleshooting you are all even. Same Cable Type (Make/Model) as well. With regards to my own system, all battery cables are Royal Excelene Welding Cable which is Very Fine Strand 110 Pure Copper and using closed end Tinned SelTerm wire ends https://selterm.com/

 

[OffGridInTheCity]

My Powerwall is pretty balanced cable wise length and inverter take-off +/- are very similar (~5ft). However, the overall Powerwall is pretty large physically so the main (4/0 AWG) positive is ~10ft and the main negative (4/0 AWG) is ~15ft leading to the control box/main-buss - e.g. 5 foot difference. Batrium doesn't reveal any issues with the individual packs and I don't need regular balance. But, the load is on the low stress end relative to the battery bank size.

My current opinion is that the issues around this topic are significantly affected by buss vs daisy-chaining parallel batteries and the relative load on the system. Low load (low stress) powerwall wiring is more forgiving than high load (hi stress) loading.

In my case, low stress means 1) <190ma/18650-cell charge/discharge and 2) <150a on 4/0 AWG wire paralleling all the batteries. I imaging if I were running a hi stress load on the same system - e.g. 500ma/cell and 300a on 4/0 AWG it might be different.