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How to check a used BYD Seal battery: size, warranty, recalls and health (UK)

Published 2026-11-06 · Last updated 2026-11-07 · based on 19 sourced Seal data points and 29 sources

The BYD Seal is a large LFP "Blade" saloon sold in the UK from late 2023 with an 82.5 kWh usable pack on Design (RWD) and Excellence (AWD). On the 11 UK dealer AVILOO certificates we found, results ranged from 98.0%–99.9%. The bigger questions on a used Seal are BYD's warranty mileage conflict (250,000 km in the manual vs 200,000 km on the UK web page), how far to trust the car's own battery figure, and how an independent test compares with other Seals. This guide covers each check.

All figures with method and date: used BYD Seal battery data. Going to a viewing? Make a printable list of questions for the seller. Sister BYD guide: Atto 3 battery check. More Chinese-brand EVs: Chinese EVs battery guide.

1. Battery size: 82.5 kWh LFP Blade (UK Design & Excellence)

EV Database UK listings, checked 2026-11-06. Test certificates usually print 82.56 kWh. All 11 of our UK dealer certificates are for that 82.56 kWh pack.

• Design and Excellence share the same battery; the difference is one motor vs two (and performance).
• EV Database lists a smaller Comfort pack at 61.4 kWh usable / 63.0 kWh nominal as Not Available in the UK (EV Database).
• AVILOO also lists a 64 kWh Seal pack for FLASH-test coverage (AVILOO GmbH). For a privately imported car, check which pack it has and whether the UK warranty applies.

2. Check for recalls

When we checked DVSA's recall file (DVSA; Seal rows re-checked 2026-11-06 against the 2026-10-31 download), it listed no recall under the Seal passenger-car name and no high-voltage battery recall for the Seal. The BYD rows in that file are for buses and coaches (Enviro, K8/K9, D8/D9, B11/B12), not the Seal saloon. Some BYD entries list only model codes, and the file can lag behind new campaigns, so this isn't proof that a car is clear. Run the free GOV.UK recall check on the registration (GOV.UK) and ask a BYD dealer to check the VIN for open campaigns and software updates.

3. Check the battery warranty (and which mileage applies)

BYD's sources don't agree on the mileage, so here is what each says (same conflict as on the Atto 3):

• The manual and the newer press release both say 250,000 km. As the web page still says 200,000 km, ask a BYD dealer or BYD UK to confirm the cover for the car's VIN in writing, especially on a high-mileage car.
• Count the 8 years from the first registration date. EV Database lists UK Design/Excellence orders from September 2023, so even the oldest cars on that listing stay inside the 8 years until about 2031 – check the date on the V5C.
• The cover is for capacity falling below 70%. Gradual loss above that isn't covered. If the battery is repaired under warranty, BYD may use a new, reconditioned or remanufactured part, and says the replacement will have at least the capacity the original had before the failure, not "as new" (BYD).
• The manual excludes, among other things, damage from leaving the car with the battery at zero charge, physical damage, flood damage, and opening or servicing the battery anywhere other than a BYD-certified technician. BYD UK's page says the warranty may not be valid if the car wasn't serviced to BYD's schedule (BYD UK). Ask for the BYD service history and look underneath for damage to the battery casing.
• Our battery warranty checker works out the time and mileage left from the registration date.

4. Get a battery reading you can trust

• Don't trust the car's own figure alone. On the 11 UK AVILOO certificates that also print the car's own BMS figure, the car's own reading was higher on 10, lower on 1 and the same on 0, by up to about 2.1 points (several cars showed BMS readings above 100%).
• AVILOO lists FLASH-test support for the Seal (AVILOO GmbH). An independent test (AVILOO GmbH) gives a figure you can compare with the table below. UK options and prices: UK battery test comparison. To read the result: certificate guide.

5. Compare the result with other Seals

• No AVILOO median is published for the Seal itself. Every figure below is a single car (n=1).
• The 11 UK dealer AVILOO certificates (all 82.56 kWh; 2,049–40,098 km, ≈1,273–24,916 miles) read 98.0%–99.9%. The lowest, 98.0%, was at 24,916 miles; the highest-mileage UK car (24,916 miles) had 98.0%.
• 2 Australian dealer AVILOO certificates (hot climate – not UK conditions) read 97.6%–97.9% at 42,316–50,559 km.
• 6 other single-car results (owner forums, Reddit and an InsideEVs OBD reading) ranged 95.1%–99.9%. Owner-app and car-reported rows are not independent tests – treat them as examples only. One German owner reported an AVILOO result of 96.7% at 82,000 km after DC-only charging.
• A UK independent result clearly below about 98.0% at similar low-to-mid mileage is worth questioning. Get the car tested again or ask BYD to check it.
• As a rule of thumb for all EVs, ADAC expects at least 92% at 50,000 km, 88% at 100,000 km, 84% at 150,000 km, 80% at 200,000 km (ADAC).
• Compare the Seal with other Chinese-brand EVs on the battery degradation chart, or get a quick estimate with the battery health estimator.

Every Seal single-car result we have (n=1 each)

11 UK and 2 Australian dealer AVILOO certificates and 6 other single-car readings. Single cars show the spread, not an average. Owner-app and car-reported rows are not independent tests. Every row is also on the Seal data page.

6. Battery replacement cost (UK)

We have not found a verifiable, dated UK price for a new Seal battery from BYD, so we don't quote one. Inside 8 years and the warranty mileage, a battery below 70% capacity is covered by BYD (BYD). For a car near the end of its cover, get a written quote from a BYD dealer before you buy. General UK figures are in our EV battery replacement cost guide.

Also see: BYD Atto 3 battery check · BYD Dolphin battery check · Chinese EVs battery guide (MG, BYD, Polestar…) · MG4 LFP vs NMC battery · general used-EV battery checklist · battery problem after buying: your rights (UK) · all models compared.

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