Flipping the negative bus bar in EG4 battery cabinet

[SunFarmer]

Hello Forum,

I’m at the verge of a exciting milestone on my off-grid solar electric project; ordering an inverter and batteries. Seeking expertise from forum members with the following question:

I’m planning to purchase three of the EG4-LifePower4 batteries and a 6-slot EG4 battery rack. I’ve read and seen videos of folks flipping the negative bus bar upside down so that the positive cable connects the bus bar at the top and negative cable connects to the bus bar at the bottom. Is this really necessary? I’m planning to install my inverter very close to the battery rack and want to keep the big 48V DC cables as short as possible and equal length. Flipping the negative bus bar upside-down would require extending the negative cable (and hence the positive cable as well) an extra couple of feet.

Thanks in advance for your sage advice.

 

[John Frum]

Why you need to extend the positive cable?

 

[OffgridMatty]

I have done it with my two Lifepower4 batteries and bus bar. I've read it allows for better balance between the batteries output and figured it's worth the cost of additional wire length. I didn't test it any other way so don't have data to prove it made a difference.

 

[Darren67-72]

Or, you can save yourself the work and just drill a, like sized, hole at the bottom of the buss bar and bolt the connector there.
And, I agree.... the wires from the buss bars to the inverter do not have to be the same length. I'd keep them as short as possible.

 

[Darren67-72]

As for the need to even bother... There are many arguments about this theory. The old "right" theory was that electricity takes the path of least resistance (and everybody KNEW they were right) now it has been proven, that electricity takes ALL paths back to source.
With that being said, some now extrapolate, that with buss bars, you can just attach both leads to the top. Same vs. Same.
I still attached the negative wire to the bottom.?????

 

[John Frum]

If the positive inverter lead is connected to the top of the busbar then the negative lead should be attached to the bottom.
Attaching the inverter leads at opposite ends cancels out the incremental resistance along the busbars.
The battery leads should be the same length to keep the path resistance as equitable as possible.
The inverter leads do not need to be the same length.

 

[OffgridMatty]

If the positive inverter lead is connected to the top of the busbar then the negative lead should be attached to the bottom.
Attaching the inverter leads at opposite ends cancels out the incremental resistance along the busbars.
The battery leads should be the same length to keep the path resistance as equitable as possible.
The inverter leads do not need to be the same length.

This is how mine is set up. My batteries discharge equally and have maintained good balance when tested using the BMS software from Signature Solar.