BMS hardware must handle small sensing signals while preserving a high-voltage safety boundary. Contact-resistance drift, SMT hardware opens and Cu-Al corrosion can otherwise be mistaken for a cell or software issue.
Manage sensing and power paths as separate functions
Define the sensing reference, harness direction and shielding separately from continuous, surge and short-circuit power paths. High-voltage boxes also need explicit creepage, fuse service space and insulation-part tolerances.
Inspect SMT terminals and threaded hardware
Check coplanarity, paste openings, pick-up surfaces and the reflow profile at the land-pattern stage. Threaded hardware needs torque, pad-peel and anti-wicking validation. Link incoming material, placement, reflow and resistance data by lot.
- Sensing terminals: four-wire resistance before and after cycling
- Power terminals: current, temperature rise, voltage drop and torque retention
- Environment: select thermal, humidity, vibration and salt tests for the pack
Define the Cu-Al transition boundary
When aluminum cells or housings meet copper PCB terminals, drawings should state copper/aluminum orientation, end sealing and plating keep-outs. Bond strength alone does not establish system life; the full hardware and environment still require validation.