Rizel EV Engineering: Battery, Motor and Vehicle Network

The engineering inside the Rizel program, in one deep page: the 320 V battery system and its BMS board revisions, the EMRAX and Bamocar powertrain bring-up, and the CAN network that carried diagnostics and telemetry between every system.

I led this engineering. This page goes deeper than the case study overview.

The battery came first. Cells were grouped into serviceable modules, nickel strips across cells in molded holders, copper busbars between modules, roughly 89S32P for about 2,850 Samsung 18650 25R cells and 25.6 kWh nominal. We drew 320 amps continuously at about 10 amps per cell, half the cell's rating, deliberate thermal margin. The BMS went through the revisions you can see on this page: the test series (1.2.1, then 1.2.2), then PROTOTYPE VER 2.1.1, each tightening the sensing. On the running prototype, an Orion BMS carried supervision while our boards matured. One revision taught the best lesson: a cell-group reading that looked fine at rest drifted under load, under-reporting a real imbalance, which is exactly the failure a BMS exists to catch.

The powertrain was an EMRAX axial-flux machine driven by a UniTek Bamocar D3. Bring-up meant matching controller to motor, current limits, thermal behaviour, and making the controller and BMS agree about what the pack could deliver at any moment. Under it all ran the CAN network: the BMS, controller and vehicle systems talking, with diagnostics and telemetry that turned mysterious faults into specific ones. On a prototype, that is the difference between guessing and knowing. The early packs also taught serviceability the hard way. One bad cell meant hours of unpacking and repacking, so later designs made modules swappable.

Technical scope

• ≈89S32P pack, ≈2,850 Samsung INR18650-25R cells, ≈25.6 kWh nominal, 320 V / 320 A
• BMS test-series boards 1.2.1 and 1.2.2, then prototype 2.1.1, alongside Orion BMS supervision
• EMRAX motor with UniTek Bamocar D3 control; CAN diagnostics and telemetry
• Precharge, contactor and HVIL safety chain; thermal paths

Status — The engineering chapters of the 2017–2020 program, in one place.