I have designed the battery too. It has 10mm thick printed walls that bolt together, forming a frame. They were spray painted with clear coat to isolate from water intrusion between layers. Two Plexiglas sheets with countersunk holes are secured in the frame with M3 screws and heated inserts. This was sealed with SikaFlex 591 as it should be more modern and UV resistant than 291i. A foldable handle is included as well.
I have made two modular cell packs that simply slot in place along with the BMS. I changed the BMS’s cables for 14 AWG instead of 7 AWG, as it is charge-only.
A formal wiring diagram is not available, so the battery configuration is described below.
The complete battery pack consists of 32 cells configured as a 16S2P pack. The cells are physically arranged as two 16-cell packs positioned side by side (left and right). Two different wiring approaches were considered for connecting these packs.
The first approach was to wire the left and right 16-cell packs independently in series (16S) and then connect the two completed packs in parallel. While electrically equivalent, this arrangement would have complicated the BMS wiring, as each balance lead would have needed to be connected to the corresponding voltage node on both 16S packs.
Instead, the implemented configuration connects the corresponding cells of the left and right packs in parallel at each series position, forming sixteen 2P cell groups. These parallel groups are then connected in series to create the final 16S2P battery pack. This arrangement allows each BMS balance lead to connect to a single series node, resulting in a significantly simpler and cleaner wiring layout while maintaining the same electrical configuration.
The two temperature probes are inserted in the middle of the packs.
I really like JIKONG’s app. I use the one called “JK BMS”. I took some screenshots of the first charge test.
I stress tested 20A charging (1168W) successfully too, even though the 14 AWG cables warmed up slightly.
