Must battery cables be equal length?

[New-B]

In keeping the wires the same length in paralleled battery banks, do you have to include in the measurement the additional length added by the BMS wires and shunt on the negative wire?

 

[TampaSteve]

The general consensus is that for Lithium this is less critical than lead acid where its a deal killer. I know of one case where Battleborn approved a second set of batteries 10 FEET away! But their logic was, as long as you try to charge the whole bank full once a week so everybody gets balanced, its usable if not ideal.

For my own wiring I used the common bus bar with point to point wiring instead. I've seen engineering studies that its significantly better than the common diagonals method.

Lots of other good reasons - I have separate fuses for each battery and an easy way to disconnect one if it fails. Also for this method you can use smaller cables on the individual batteries. And lastly if I want to put one battery further I could use 4/0 instead of 2/0 to send up with the same resistance.

But I wouldn't fret over a few inches.

 

[New-B]

The general consensus is that for Lithium this is less critical than lead acid where its a deal killer. I know of one case where Battleborn approved a second set of batteries 10 FEET away! But their logic was, as long as you try to charge the whole bank full once a week so everybody gets balanced, its usable if not ideal.

For my own wiring I used the common bus bar with point to point wiring instead. I've seen engineering studies that its significantly better than the common diagonals method.

Lots of other good reasons - I have separate fuses for each battery and an easy way to disconnect one if it fails. Also for this method you can use smaller cables on the individual batteries. And lastly if I want to put one battery further I could use 4/0 instead of 2/0 to send up with the same resistance.

But I wouldn't fret over a few inches.

Oh ok. That puts my mind at ease. Thanks for the info

 

[time2roll]

I would far prefer to avoid the intra-battery cables and connect each with separate wires to a bus.
Expansion is easy, service or replacement of one battery is easy.

https://shop.pkys.com/Blue-Sea-2127-Maxibus-BusBar-250-Amps_p_2775.html

 

[off.the.grid]

Just stumbled across this thread and thought I would ask here instead of starting a new one.
Is this layout ive done withbthe busbars ok?
It's the tidest way I could come up with arranging.
Also, is there much benefit in cutting down the old battery leads to the inverter?
They don't need to be quite as long, so could almost remove about a metre from them if it's going to have any noticeable benefit.

 

[FilterGuy]

Just stumbled across this thread and thought I would ask here instead of starting a new one.
Is this layout ive done withbthe busbars ok?
It's the tidest way I could come up with arranging.
Also, is there much benefit in cutting down the old battery leads to the inverter?
They don't need to be quite as long, so could almost remove about a metre from them if it's going to have any noticeable benefit.
View attachment 99687
View attachment 99686

I see nothing wrong with the set up.... but it is rather unique. Comming off the batteries the length of the negative and positive do not need to be the same length. If you can shorten them by a meter... do it.

 

[curiouscarbon]

looks good to me.

the resistance reduction is nice with shorter distance

both nearby conductors are both insulated with something that looks like probably rated at least 120V (some insulation rated 600V+)

even if insulation melts, the voltage across the two should be less than 30V

no problem

Just stumbled across this thread and thought I would ask here instead of starting a new one.
Is this layout ive done withbthe busbars ok?
It's the tidest way I could come up with arranging.
Also, is there much benefit in cutting down the old battery leads to the inverter?
They don't need to be quite as long, so could almost remove about a metre from them if it's going to have any noticeable benefit.
View attachment 99687
View attachment 99686

 

[chess-equality]

Just stumbled across this thread and thought I would ask here instead of starting a new one.
Is this layout ive done withbthe busbars ok?
It's the tidest way I could come up with arranging.
Also, is there much benefit in cutting down the old battery leads to the inverter?
They don't need to be quite as long, so could almost remove about a metre from them if it's going to have any noticeable benefit.
View attachment 99687
View attachment 99686

Where did you buy these busbars?

 

[off.the.grid]

Where did you buy these busbars?

I bought the busbar strip from an electrical wholesaler. They also build switchboards.
It's pure copper and tin plated.

I see nothing wrong with the set up.... but it is rather unique. Comming off the batteries the length of the negative and positive do not need to be the same length. If you can shorten them by a meter... do it.

Yeah its a bit unusual. If I had a 48V system it would have been much easier to wire all 4 batteries in series. Not too sure how common it is to see these kind of batteries in this layout. If they had terminals at each end, that would have made it easier.

looks good to me.

the resistance reduction is nice with shorter distance

both nearby conductors are both insulated with something that looks like probably rated at least 120V (some insulation rated 600V+)

even if insulation melts, the voltage across the two should be less than 30V

no problem

I thought it would be a good idea to insulate the bars in the center, so I used heatshrink.
I think its rated at 600V, so should be safe.
The main risk would have been if something metal ever crossed over and shorted them.

 

[Supervstech]

Just stumbled across this thread and thought I would ask here instead of starting a new one.
Is this layout ive done withbthe busbars ok?
It's the tidest way I could come up with arranging.
Also, is there much benefit in cutting down the old battery leads to the inverter?
They don't need to be quite as long, so could almost remove about a metre from them if it's going to have any noticeable benefit.
View attachment 99687
View attachment 99686

Is the FLA bank connected to the SLA bank?

 

[off.the.grid]

Is the FLA bank connected to the SLA bank?

Nope, that's the old bank you see.
I'm about to switch everything over once I know it's all charging OK.