EV charging time and cost equations
The battery receives less energy than the supply delivers because charging is not perfectly efficient.
Ebatt = C × (SOCtarget − SOCstart)Ewall = Ebatt / ηt = Ewall / PchargerCost = Ewall × tariffwhere:
- C
- Usable battery capacity[kWh]
- SOC
- State of charge
- η
- Charging efficiency
- t
- Charging time[h]
Actual time can be longer when the vehicle tapers charging power.
How to use the EV Charging Time and Cost Calculator
Estimate EV charging time, delivered energy, wall energy, and cost from battery state of charge and charger power. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Constant average charging power Battery capacity is usable capacity Tapering and thermal limits are represented only by average power A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Constant average charging power
- Battery capacity is usable capacity
- Tapering and thermal limits are represented only by average power
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
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Assumptions
- Constant average charging power
- Battery capacity is usable capacity
- Tapering and thermal limits are represented only by average power
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.