OWNER ANSWER
Why charging kWh does not match your BYD’s battery percentage
A charging receipt measures supplied energy, not simply the battery percentage gained. Understand charging losses, cabin use and a careful worked example before assuming a fault.
The electricity shown on a charger receipt and the rise in your battery percentage describe different things. Osprey explains that supplied energy can also cover conversion losses and vehicle systems such as battery temperature management and pre-conditioning. A mismatch alone therefore does not establish a damaged battery or an incorrect bill. Equally, it should not be used to dismiss a repeated unexplained discrepancy without checking the records.
- Start with the units. kW is a rate of power; kWh is an amount of energy. Do not compare a charger’s advertised maximum kW with the session’s billed kWh as though they were the same measurement.
- Record starting and finishing battery percentages before driving away, together with the session kWh. Use readings from the same session and note whether you had heating, cooling or pre-conditioning running.
- If you want a rough calculation, first obtain the correct usable battery capacity for the exact version. Do not silently substitute a gross/nominal number, another trim or a different model year. If the capacity basis is unknown, leave the calculation as an estimate rather than a precise efficiency result.
- Worked example, not a BYD specification: suppose a hypothetical usable 60 kWh battery rises from 20% to 70%. The change is 50 percentage points, so a simple estimate is 60 × 0.50 = 30 kWh stored. A 34 kWh receipt would leave a 4 kWh difference to investigate, not prove 4 kWh of faulty billing.
- In that example, 30 ÷ 34 × 100 is about 88%. This is only a rough session comparison, not a battery-health percentage or a certified charging-efficiency test. Rounded dashboard readings and uncertain capacity assumptions affect the answer.
- Keep the measurement boundary consistent. A whole-house meter can include household electricity; a charger session and the car’s battery display refer to different points in the process. Compare matched records rather than yesterday’s household total with today’s car reading.
- If a pattern worries you, collect several comparable sessions with temperatures, AC/DC type, times and cabin-use notes. Query a questionable receipt with the operator, or a repeatable vehicle concern with BYD. Warnings, overheating or damage need the appropriate immediate safety response, not more experimental charging.
Is 10–15% extra always normal for my BYD?
This guide does not set a universal percentage. Conditions and measurement points differ. A generic network example is not an acceptance limit for every BYD battery, charger or session.
Does DC rapid charging remove every loss?
No. AC charging converts power to DC in the vehicle; a DC charge does not use that same onboard conversion route, but vehicle energy use and other losses do not disappear.
Can I calculate battery health from one charging receipt?
No. Dividing billed energy by a percentage change is not a verified state-of-health test. Use the appropriate BYD assessment route for a battery-health concern.
Should I change my charging target because of this?
Not on the basis of this arithmetic alone. Follow the battery-care guidance for your exact vehicle and handbook edition, including any required full-charge instructions.
Osprey Charging — supplied kWh, conversion and vehicle-system energy; checked 14 October 2026
Open sourceOctopus Electroverse — kW versus kWh; checked 14 October 2026
Open source