Charging losses: why your meter shows more kWh than your battery took
Home AC charging typically loses 10–15%of the energy you pay for before it reaches the battery — heat in the cable, the onboard charger, and the car’s electronics staying awake. We assume 12% in every figure on this site, so our costs reflect what your meter records, not the optimistic battery-only number.
Prices based on the Ofgem price cap of 26.11 p/kWh, effective 1 July 2026.Source: Ofgem
Where the energy goes
The grid supplies alternating current; the battery stores direct current. The car’s onboard charger does the conversion, and no converter is perfect — the difference leaves as heat. Slower charging generally loses proportionally more, because the car’s electronics draw a fixed overhead for the whole session: a 12% loss on a 7 kW wallbox can become 15%+ on a three-pin plug’s much longer sessions.
None of this is a fault, and no brand escapes it. It just means a “60 kWh” charge is never 60 kWh at the meter — and any cost calculation that ignores it flatters the result. That is why every number on this site includes losses, and says so.
What losses cost per full charge, every model we track
| Model | Battery (usable) | Energy at the meter | The loss | Loss cost per full charge |
|---|---|---|---|---|
| Fiat 500e | 37.3 kWh | 42.4 kWh | 5.1 kWh | £1.33 |
| Nissan Leaf | 39 kWh | 44.3 kWh | 5.3 kWh | £1.39 |
| Vauxhall Corsa Electric | 46.3 kWh | 52.6 kWh | 6.3 kWh | £1.65 |
| Peugeot e-208 | 46.3 kWh | 52.6 kWh | 6.3 kWh | £1.65 |
| MG MG4 EV | 50.8 kWh | 57.7 kWh | 6.9 kWh | £1.81 |
| Tesla Model 3 | 57.5 kWh | 65.3 kWh | 7.8 kWh | £2.05 |
| Volkswagen ID.3 | 58 kWh | 65.9 kWh | 7.9 kWh | £2.07 |
| Cupra Born | 58 kWh | 65.9 kWh | 7.9 kWh | £2.07 |
| Renault Megane E-Tech | 60 kWh | 68.2 kWh | 8.2 kWh | £2.14 |
| BYD Atto 3 | 60.5 kWh | 68.8 kWh | 8.3 kWh | £2.15 |
| Smart #1 | 62 kWh | 70.5 kWh | 8.5 kWh | £2.21 |
| Volvo EX30 | 64 kWh | 72.7 kWh | 8.7 kWh | £2.28 |
| Kia Niro EV | 64.8 kWh | 73.6 kWh | 8.8 kWh | £2.31 |
| Hyundai Kona Electric | 65.4 kWh | 74.3 kWh | 8.9 kWh | £2.33 |
| Polestar 2 | 67 kWh | 76.1 kWh | 9.1 kWh | £2.39 |
| MG ZS EV | 68.3 kWh | 77.6 kWh | 9.3 kWh | £2.43 |
| Kia EV6 | 74 kWh | 84.1 kWh | 10.1 kWh | £2.63 |
| Hyundai IONIQ 5 | 74 kWh | 84.1 kWh | 10.1 kWh | £2.63 |
| Tesla Model Y | 75 kWh | 85.2 kWh | 10.2 kWh | £2.67 |
| Volkswagen ID.4 | 77 kWh | 87.5 kWh | 10.5 kWh | £2.74 |
| Volkswagen ID.7 | 77 kWh | 87.5 kWh | 10.5 kWh | £2.74 |
| Skoda Enyaq | 77 kWh | 87.5 kWh | 10.5 kWh | £2.74 |
| Kia EV3 | 78 kWh | 88.6 kWh | 10.6 kWh | £2.78 |
At the July 2026 Ofgem price cap (26.11p/kWh) and our standard 12% loss assumption. On a cheap overnight tariff the loss costs proportionally less — another argument for off-peak charging.
Keeping losses down
Prefer the wallbox to the three-pin
Shorter sessions mean less fixed overhead. A 7 kW charge wastes measurably less than the same energy through a 2.3 kW socket — see our three-pin guide for the time difference too.
Avoid trickle-topping to 100% daily
The last few percent charge slowly, which stretches session length and overhead. Charging to 80% for daily use is both battery-friendly and slightly more efficient per mile added.