Help with 6S4P Battery Build / Wiring Advice Needed

Mahti28E · May 10, 2025, 5:35pm

Hi everyone,

I’m building my first eFoil and have already managed to test it a few times using four 6S 4500mAh LiPo batteries in a 12S configuration. However, with this setup, I only get around 20 minutes of ride time. To increase the range, I’m planning to build two 6S4P batteries using 21700 Molicel P45A cells.

I’m planning to run the packs without a BMS, as my external charger handles cell balancing during charging. The charger only supports 6S, which is why I need the batteries to be 6S.

The main challenge I’m facing is the limited internal height of the board. If I can arrange the cells 8 side-by-side and 3 high (total of 24 cells) (horizontal orientation), the packs would fit inside. This Printables.com model 6S4P honeycomb 21700 3 row design 22.2V battery by DIY500AMP.COM | Download free STL model | Printables.com) for cell arrangement would work well for my board.

Since I’m a beginner in battery building, I want to make sure I get everything right the first time. Could someone help me figure out the best way to configure the nickel strips for this setup? I’d really appreciate any advice on proper current handling, layout, and overall build quality.

Here’s a picture of the layout:

Thanks in advance!

Foilguy · May 10, 2025, 5:57pm

Have you viewed this video and other guidance from @ludwig_bre ?

Mahti28E · May 10, 2025, 5:59pm

Thanks for the tip, I’ll look into it

Foilguy · May 10, 2025, 7:43pm

Sure lots of documented knowledge here.

rttn · May 10, 2025, 11:11pm

6s4p x 2 = 12s4p 48 cells - that’s a very heavy battery. I wouldn’t want to ride a board like that. Or do you mean a 12s2p battery split into two packs?

Mahti28E · May 11, 2025, 6:45am

Yes, the plan is to build two 6S4P battery packs, which would give a total of 12S4P with 48 cells, and the total weight would be around 3.4kg. The current 4x 4500mAh batteries weigh 2.7kg, so the increase in weight isn’t huge. Of course, I’d prefer the lightest possible setup, but I mostly use the board on a lake where there aren’t often big waves to ride, which is why I need to increase the battery capacity for longer range.

rttn · May 11, 2025, 11:53am

Oops, sorry. For some reason I thought it was a foil assist.

rttn · May 11, 2025, 12:32pm

I don’t claim to have the truth, but I would suggest the following scheme.

Mahti28E · May 11, 2025, 6:14pm

Thanks for your message and suggestion! I actually received the following layout from the DIY500AMP model creator. It’s slightly different but both approaches are solid - appreciate the help!