EV Charging Time Calculator

EV charging time: how to estimate it

The math is time_h = capacity_kWh × target_SOC / (power_kW × efficiency). Plug into a residential outlet at 220 V / 16 A and you get roughly 3.5 kW, so a 60 kWh battery starting from empty needs about 20 hours. A 7.4 kW wallbox brings that down to around 10 hours. Go to an 11 kW three-phase unit and you are looking at roughly 6 hours. DC fast chargers sit in the 50-150 kW range and cover 10-80% in 30-60 minutes, while a Tesla Supercharger V3 (250 kW) manages that same 10-80% in about 20 minutes. Past 80% things slow to a crawl because of the CC-CV curve, which is exactly why fast-charge specs are always quoted as "10-80%". Preconditioning the battery (via Tesla nav, for instance) warms the pack before you arrive and cuts DC charging time quite a bit. To give a concrete case: 40 kWh at 11 kW with 90% efficiency works out to 4.0 hours.

Applications

Think trip planning for longer routes, weighing public stations against each other (Tupi, ZL Energy, Voltbras in Brazil), deciding whether an AC or DC stop makes sense, working out cost per km, and figuring whether a home wallbox is enough or you need a three-phase upgrade.

FAQ

Why is going from 80% to 100% so slow? Past 80% the CC-CV curve cuts current sharply to protect the cells. On a DC fast charger that last 20% can eat up as much time as the previous 60% did.

AC or DC for daily use? Charging on AC at home overnight costs less and is kinder to the battery. Save DC fast charging for road trips, since leaning on it every day can speed up degradation.

Does the rated charger power always apply? No. Your car's onboard charger sets the ceiling on AC speed, often 7.4 or 11 kW, and on DC the BMS throttles things according to temperature and SOC.