Rebuilding 48V Flat

Module layouts

The group 1 is the one furthest away from the BMS. With the 'old method' before the laser cut nickel sheets:

Nickel pieces

Sense harness lengths

Including the connector, including the end of the wire.

Other wire lengths

BMS P- cut short to 67 mm

BMS B- extended with AWG16. Cut to fit nicely to the other end. Soldering in B- is the very last step.

P+ 108 mm total, 37 mm on connector side, 44mm on battery side of fuse holder.

SOC board + and - are 72 mm each, use the scrap sense wires, and connect directly to the discharge connector.

Epoxy on the connector

One full Chinese A+B epoxy.

Arrangement on the BMS end

Final

Assembly learnings

• Between modules 3 and 4, the pins need to be longer, and some need to go to the side to avoid interference with the screws!!
• Welding with the scissor was very problematic - read the learnings and fix here.
• The turnaround 6p should have its sense pin on top, not on the side
• The battery shakes inside sideways in the end piece, further away from the BMS end. I needed to put in some foam.
• The 4 cell group interconnector wires need to be measured. Bit annoying to install them. I wish for a more efficient solution.
• Maybe the sense harness could be 1 mm shorter everywhere to give a little more space?
• The BMS-area is crowded and disorderly. No space for a holder.
• I wish for nicer sense harness. The original is much better.
  • They have low diameter wires, much more suitable
  • They have clips on the spacers 

In the process of the assembly;

• I uncovered the button-issue long plaguing us: 1k pulldown resistor is needed, not 10 or 100k.
• I fixed the scissor welding: now using the DC welder and a custom weld profile and holding the scissor loose, I get perfect welds right away every time.