cable size for between cells when paralleling 16s 280ah

[IrishG]

Im looking to top balance a 48v 16s 280k battery kit (200a seplos BMS) without disabling it and keeping the cells compressed in the case. So I would be disconnecting the busbars that are in series and replacing with cables in parallel. Planning to charge with 3.65 @ 85amp. What size cable will I need between cells?

thanks
G

 

[SeaGal]

Why 85A? Are you in a hurry?

Better to get the pack as fully charged as possible in series first, then charge up with a 10A bench power supply or similar, IMHO.

Here is @FilterGuy's excellent guide to top balancing...

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

 

[IrishG]

Not particualry in rush. I have 4 battery packs and the charger I have is up to 85amp. . However I will have the batteries before the inverters arrive so I wont be able to charge in series without buying a charger able to charge to ~56v. So I thought I could top balance them in advance in paralell first @3.6v and also capacity test a cell to make sure im not ripped off.

Would be usefull to know what mm2 or Awg cables to use between cells as busbars means having to reorientate them. Not sure calculations are done in this scenario

 

[Steve_S]

I use the busbars to put all cells in series then apply the charger to take them up to 3.600 V and allow the Amps to fall to 0.05 of their capacity.
For 280AH battery cells, that is 14A (280AH X 0.05) which is also the EndAmps/TailCurrent.

Cells need to be Top Balanced after production, or long-term storage to fully activate the cells. This is only required once, prior to assembly into a pack.

Note that even after a full Top Balance to 3.600, LFP "will settle" which is perfectly normal for LFP as it's working voltage range IS 3.000-3.400 with Nominal Voltage being 3.200 or 50% of SOC.

 

[SeaGal]

To handle 85A you'd be looking to use 25mm2 cable.

But to do it that way, you'd have to crimp lugs onto 16 sections of 25mm2 wire and connect it all up. Surely it would be quicker / easier just to use the busbars reconfigured to parallel the cells?