Charging an electric car takes roughly its battery size in kWh plus about 10% for charging losses. A car with a 45 kWh battery needs about 50 units (kWh) of electricity to charge fully from empty. How fast that happens depends on the charger’s power in kW and the maximum power the car accepts: a 7.2 kW home charger adds about 7 kWh per hour, while a 60 kW DC fast charger can add around 40–50 kWh in an hour. For home charging, a 7.2 kW charger typically needs a single-phase connection with enough spare load, which may mean asking your DISCOM for a load increase.
Last updated: September 2026.
kW vs kWh: The Two Numbers That Matter
- kWh (kilowatt-hour) is energy — the “size of the tank”. Your battery capacity and your electricity bill are both measured in kWh (units).
- kW (kilowatt) is power — “how fast the tap flows”. Chargers and your home’s sanctioned load are measured in kW.
Charging time ≈ energy needed (kWh) ÷ charging power (kW).
How Many kWh Does It Take to Charge an Electric Car?
| Battery size | Example cars | Approx. units for a full charge (0–100%) | Approx. units for 20–80% |
|---|---|---|---|
| 17–25 kWh | MG Comet EV, Tata Tiago EV | 19–28 kWh | 11–17 kWh |
| 30–45 kWh | Tata Punch EV, Nexon EV, MG Windsor EV | 33–50 kWh | 20–30 kWh |
| 50–60 kWh | Tata Curvv EV, Maruti e Vitara, Mahindra BE 6 | 55–66 kWh | 33–40 kWh |
| 75–80 kWh | Tata Harrier EV, Mahindra XEV 9e | 83–88 kWh | 50–53 kWh |
Figures include roughly 10% charging losses and are approximate. At a home tariff of about ₹8 per unit, a full charge of a 45 kWh car costs roughly ₹400.
How Long Does Charging Take at Different Power Levels?
| Charger | Energy added per hour (approx.) | Full charge of a 45 kWh battery |
|---|---|---|
| 3.3 kW portable / slow charger | 3 kWh | About 15–16 hours |
| 7.2 kW AC wallbox | 6.5–7 kWh | About 7 hours |
| 11 kW AC (three-phase, if the car supports it) | 10 kWh | About 4.5–5 hours |
| 30 kW DC | 25–30 kWh | 10–80% in about 1–1.25 hours |
| 60 kW DC | 40–50 kWh | 10–80% in about 45–60 minutes |
Two limits apply: on AC, the car’s on-board charger caps the speed (a 7.2 kW car will not charge faster on a 22 kW AC charger); on DC, the car’s maximum DC rate caps it. Fast charging also slows down above about 80% to protect the battery.
How Much Electricity Does an EV Use per Kilometre?
Most electric cars in India use roughly 12–18 kWh per 100 km in real-world driving — smaller hatchbacks at the lower end, larger SUVs and highway driving at the higher end. At ₹8 per unit, that is about ₹1–1.5 per km when charging at home.
Power Requirements for Charging at Home
- Sanctioned load: a 7.2 kW wallbox draws about 7 kW for hours at a time. Many homes have a sanctioned load of 3–5 kW, so you may need to apply to your DISCOM for a load increase, or install a separate EV connection where your state offers one.
- Single-phase vs three-phase: up to about 7.4 kW works on single-phase; 11 kW and 22 kW AC charging need a three-phase supply and a car that supports it.
- Wiring and protection: a dedicated circuit with correctly rated cable, an MCB and an RCD/RCCB, installed by a qualified electrician.
- Load management: a smart charger can reduce its power when other appliances run, avoiding trips and extra load charges.
In apartments, the society’s electrical capacity and approvals also matter — see EV charging for homes and apartments.
Power Requirements for Commercial Charging Stations
A public DC charger needs far more power: a single 60 kW charger needs about 60–70 kW of connected load, and multi-charger highway hubs often need a dedicated transformer. That is why the electricity connection is one of the biggest parts of setting up a station — see EV charging station setup requirements and dynamic load management. EarthtronEV handles the load assessment, EV connection and transformer work for its EV charging station franchise partners.
Related Reading
- What Is an On-Board Charger (OBC) in an Electric Vehicle?
- EV Charger and Connector Types in India: Type 2, CCS2, Bharat and More
- AC vs DC EV Chargers: Which One Is Best for Your EV Charging Station?
- Smart EV Charging and Dynamic Load Management in India: How Stations Can Reduce Peak Electricity Costs
Frequently Asked Questions
How many kWh does it take to charge an electric car?
About the battery capacity plus 10% for losses. A 45 kWh battery needs roughly 50 kWh (units) for a full charge, or about 30 kWh from 20% to 80%.
How much electricity does an EV charger use?
A charger uses power equal to its rating while charging: a 7.2 kW home charger uses about 7 kWh (units) every hour. Total use depends on how much energy the car needs.
How many kilowatts do I need to charge an electric car at home?
A 3.3 kW supply is enough for slow overnight top-ups, but a 7.2 kW wallbox is the common choice for full overnight charging. Make sure your sanctioned load can handle it; you may need a load increase from your DISCOM.
Why doesn’t my car charge faster on a 22 kW AC charger?
Because AC charging speed is limited by the car’s on-board charger. Most Indian EVs accept 7.2 kW or 11 kW on AC; for faster charging, use a DC fast charger.