BMS

Most battery models fail not because the equations are wrong — but because the assumptions smuggled in with them are wrong. Fifteen years working with battery models across the stack: from ECM spreadsheets that needed to survive a BMS real-time loop, to full electrochemical models trying to capture what actually happens inside the cell during a fast charge. The gap between “runs on paper” and “works in a vehicle” is where most of the interesting problems live. ...

Most battery simulation work happens inside large OEM simulation frameworks — tools with hundreds of subsystems, long setup times, and infrastructure built for full-vehicle analysis. Useful when you need the full vehicle. Counterproductive when you need to iterate quickly on battery-specific questions. At Volvo Trucks, the problem was clear: the battery and BMS teams needed a simulation environment they could actually use — fast iteration, battery-focused, not dragging a full vehicle model along for every run. ...

The EV marketing spec says “0 to 80% in 22 minutes.” It rarely says how long 80 to 100% takes. The omission is deliberate — and it reveals something fundamental about how lithium-ion cells actually work. The CC-CV Profile and Why the Transition Matters Lithium-ion charging follows a two-phase profile, not because someone decided it was a good idea, but because cell physics demands it. Constant Current (CC) phase: You push current in at a fixed rate. The cell voltage rises as SoC increases. This phase is efficient — you’re putting energy into the cell at the maximum rate the chemistry allows without exceeding the voltage limit or driving electrochemical side reactions. ...