Compute the voltage difference between your Li-ion cells and the balancing current required — whether you're designing a BMS, diagnosing a pack, or choosing between active and passive balancing.
Fill in your cell specifications to compute balance metrics.
Based on the parameters above.
For most lithium-ion packs, ΔV should stay below 20–50 mV. Above 100 mV indicates imbalance requiring BMS intervention. EV and drone applications often target under 10 mV.
Use I_balance = (C × ΔV) / (t × V_nom). A 3000 mAh cell with 100 mV difference balanced over 4 hours requires ~75 mA. Passive BMS usually offers 20–100 mA; active balancers deliver 500 mA to several amps.
Passive balancing is cheaper and simpler — great for 2S–4S packs with mild imbalance. Active balancing transfers energy between cells with 90%+ efficiency, ideal for EVs and large energy storage where speed and energy loss matter.