The Battery C-Rate Safety Calculator estimates how much current your eBike battery can safely deliver based on capacity, cell chemistry, controller draw and BMS rating. The C-rate defines how quickly a battery can be discharged relative to its capacity. Higher C-rate means higher current output, but also more heat stress and faster degradation.
C-rate describes the rate of discharge relative to battery capacity. A 1C discharge drains the full battery in one hour. For example, a 20Ah battery at 1C can deliver 20A continuously, while a 2C rating would allow 40A. Lithium-ion eBike batteries typically operate safely between 1C and 2.5C depending on cell quality and cooling.
C-rate limits depend on BMS rating, controller demand and internal cell resistance. Exceeding safe discharge levels causes heat buildup and long-term cell stress. Continuous C-rate matters more than short peak bursts. Most eBike packs should maintain controller draw lower than BMS continuous current, ideally with 20–40% safety margin.
Exceeding BMS limits may cause thermal runaway, automatic shutdown or permanent damage to cells. Always match controller current to BMS capability and cell specification.
LFP cells often allow higher safe discharge with less temperature rise, while NCM/NCA cells may achieve better energy density but run warmer under heavy load.