This simulator models a representative 16-series lithium battery pack — 200 Ah at 100% health, 30 mΩ nominal internal resistance and 30 kJ/K thermal mass — as it discharges, charges at constant current, and tapers through a constant-current/constant-voltage (CC/CV) charge cycle. Watch how terminal voltage, internal heating and BMS protection limits interact as current direction and pack health change.
• A real-time 3D bidirectional DC workbench — cell modules, copper busbars, a battery management system (BMS), a DC contactor, a charger/DC load and a thermal management block — with a toggleable enclosure, auto-rotate, expand, hideable labels and selectable components with callouts. • An operating-mode selector: discharge (constant current), charge (constant current), charge (CC/CV) and idle/open load, plus sliders for requested current magnitude (0–150 A), state of charge override (5–95%), ambient temperature (−10 to 55°C) and capacity/resistance health (50–100%), and a cooling-system-available checkbox. • Playback controls: pause/resume, advance 0.1 s, advance 1 s, and a speed selector from 10× slow motion through real time to 60× faster, plus a reset-protection button and full laboratory reset. • Live readouts for terminal voltage, current (signed, + is discharge), terminal power, state of charge, pack temperature and internal heat loss, an operating-sequence narrative, and a status badge. • A Waveforms & power analysis tab with two charts (energy and thermal response), the underlying model equations, an analysis-scope note and snapshot measurements. • An Experiments tab with six guided scenarios (reverse the energy flow, observe CV taper, aged pack, current limit, empty reserve, thermal trip), a Model verification bench running independent deterministic checks against a fresh model instance, and a timestamped event log with trial-report export. • A Learn & assess tab with guided lessons, a knowledge-check quiz and a scope/references section.
Open-circuit voltage rises with state of charge (Voc = 48 + 8·SOCfraction V in this model). During discharge, internal resistance subtracts an I·R drop from that open-circuit voltage; during charge, it adds to it — which is why charging voltage always exceeds resting open-circuit voltage. SOC integrates current against amp-hour capacity, while delivered energy integrates terminal voltage times current, so the two track differently once losses matter.
In CC/CV mode, the charger holds constant current until terminal voltage approaches a 55.2 V ceiling, then tapers current to hold that ceiling as the rising open-circuit voltage leaves less resistive headroom. Resistive heating grows with the square of current (Ploss = I²R), so doubling current quadruples heat generation. The BMS restricts current to a 100 A limit regardless of what's requested, blocks discharge below a modeled reserve SOC (while still permitting charging), and latches an overtemperature trip that opens the DC contactor at 60°C pack temperature — it only resets once the pack cools below 55°C.
This is a lumped equivalent-circuit and thermal teaching model, not a manufacturer cell datasheet or commissioning tool. Reducing the health slider halves capacity and doubles resistance, so an aged pack shows greater voltage sag and heating at the same current. Chemistry-specific voltage hysteresis, lithium diffusion dynamics, cell-to-cell imbalance, long-term degradation evolution and thermal runaway are not simulated — SOC is treated as a direct setup override whenever its slider changes, not something the model derives from history.
Internal resistance creates an I·R drop. During discharge this subtracts from the open-circuit voltage (Voc), so terminal voltage is lower. During charge, the same resistance adds to Voc, so terminal (charging) voltage is higher than the resting open-circuit value.
In charge (CC/CV) mode, the charger holds constant current until terminal voltage approaches a fixed 55.2 V ceiling. As SOC rises, open-circuit voltage climbs and leaves less resistive headroom, so the charger reduces current to avoid exceeding the voltage ceiling — that reduction is the taper.
The modeled battery management system limits requested current to 100 A, blocks discharge (but not charging) once state of charge reaches a low reserve limit, and latches an overtemperature trip that opens the DC contactor at 60°C pack temperature, requiring cooling below 55°C before it can be reset.
The Experiments tab includes a Model verification bench that runs independent deterministic checks — covering SOC direction versus charge/discharge, the terminal-power-plus-heat energy balance, the 100 A current limit, the CC/CV voltage ceiling, the thermal trip, and reserve-SOC blocking — against a freshly constructed model, leaving your live experiment state untouched.