Hi All, I am struggling to find info on the internet about this. I have 6 pylon US3000C all in parrallel with BMS cables connected. The question is , having no main busbar, only pylon cables, what would be the most sensible method to uplink the batteries to the inverter. I have 3 options basically that I can think of. Please disregard all cable lengths in my drawing, My uplink cables are the same length. The question is about where to connect the uplink cables to the battery to.

Not an Option. I can use 1 + and 1 - cable at the opposite end of the bank. I prefer to overengineer stuff, so I want to go with a double cable uplink to the inverter. So this is not an option.

Option 1. I can use 1 + and 1 - cable and another 1 + and 1 - at the opposite end of the bank. This doesnt feel quite right, although this is the only method I see people use. 

Option 2. I can split the banks in 2 (3+3) and have 1 + and 1 - cable at the opposite end of the bank for each bank.  This to me feels optimised and that is what I would like to do, but I suppose my convcern is whether I will confuse the BMS. So this is my question, if not then why not 🙂 

Thanks for the inputs. 

Option 2 is correct

Have mine also wired as per option 2. No problem for the BMS as long as you have the batteries linked together

We already had this topic some time ago. https://powerforum.co.za/topic/11684-does-battery-cable-length-matter/page/2/#comment-118460

"But the impact of different length of cables is not so important, provided they have at least 25mm² section (from welding supply shop). The difference only comes into effect with very high discharging currents. These are exceptional and short events. But the difference of internal resistance of the batteries may be more important and you cannot change that. That's my experience with my 4 identical battery packs purchased at different times. When it charges to full SOC I noticed that they will equalize themself. The one with lower internal (or external) R will reach 100% SOC first but with its higher internal voltage will then draw less current, allowing the others to catch up.

The difference in internal resistance (Ri) of different battery packs is likely to be much greater than the resistance of 50cm 25mm² cable. I.E. the last pack I installed is connected at the end of the line, thus has the longest leads. Yet its Ri is so much lover than the others that it recharges and discharges quit faster than the other 3. The reason might be the fact that it is new while the others have already endured 400 and over 500 cycles. It could also be due to manufacturing inaccuracy or improvement. Perhaps its Ri might increase with age."

Edited August 25, 20223 yr by Beat

Thank you for the replies, I am more confident now to connect as per option2, Hopes this helps others too 🙂