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Chinese EVs: used battery health guide
Last updated: · 13 models · 51 sourced data points
MG, BYD, GWM Ora, Xpeng and NIO are Chinese brands; the Polestar 2, early Volvo EX30s and the first-generation Dacia Spring are built in China (Polestar, electrive.com, EV). This guide pulls together what is actually published about their batteries – chemistry, warranties, how to check a car – and is honest about how little independent SoH data exists so far.
Data reality check: only the Polestar 2 appears in a large independent dataset (AVILOO 2026: n=17,155 tests; AVILOO GmbH). For every other model here our figures are individual cars (n=1) – dealer AVILOO certificates (UK, France, Slovakia, Norway, Australia), owner-reported readings from owner forums (MG5, Ora 03, Xpeng G6, Smart #1) and Chinese used-car listings (NIO ET5). Treat them as examples, not averages.
Models covered
| Model | Chemistry | Data points | Individual results so far | Battery warranty |
|---|---|---|---|---|
| MG4 EV | Standard Range 51 kWh: LFP. Long Range 64 kWh, XPOWER 64 kWh and Extended Range 77 kWh: NMC. | 6 | 92.5%–97.6% at 20,582–42,725 km (6 single cars) | HV battery 8 yrs / 100,000 mi, below 70% capacity (MG UK statement 2025) (MG Motor UK) |
| MG ZS EV | 2019–2021 44.5 kWh and 2021–2025 72.6 kWh Long Range: NMC. 51.1 kWh Standard Range: chemistry not listed in our source. | 6 | 88.9%–100.0% at 24,000–383,024 km (6 single cars) | HV battery 8 yrs / 100,000 mi, below 70% capacity (MG UK statement 2025) (MG Motor UK) |
| MG5 EV | Facelift (2022–2025) Standard Range 50.3 kWh: LFP; Long Range 61.1 kWh: NMC. Chemistry of the 2020–2022 cars is not listed in our source. | 6 | 93.0%–99.2% at 37,000–101,400 km (6 single cars) | HV battery 8 yrs / 100,000 mi, below 70% capacity (MG UK statement 2025) (MG Motor UK) |
| BYD Atto 3 | LFP (lithium iron phosphate), BYD Blade prismatic cells. | 3 | 95.1%–96.9% at 23,332–49,050 km (3 single cars) | 8 yrs / 250,000 km (155,350 mi), SOH ≥ 70% (BYD) |
| BYD Dolphin | LFP, BYD Blade prismatic cells (44.9 and 60.5 kWh usable). | 1 | 96.6% at 7,902 km (n=1) | 8 yrs / 250,000 km (155,350 mi), SOH ≥ 70% (BYD) |
| BYD Seal | LFP, BYD Blade prismatic cells (82.5 kWh usable). | 1 | 97.9% at 50,559 km (n=1) | 8 yrs / 250,000 km (155,350 mi), SOH ≥ 70% (BYD) |
| GWM Ora 03 / Funky Cat | 47.8 kWh nominal (45.4 kWh usable): LFP. 63.1 kWh nominal (59.3 kWh usable, e.g. GT): NMC. | 5 | 88.9%–98.1% at 7,000–32,000 km (5 single cars) | 8 yrs / 100,000 mi, SoH not below 70% (GWM UK) |
| Polestar 2 | NMC for all versions (64/78 kWh 2020–2023; 70/82 kWh 2024–2025). | 10 incl. 6 multi-car | 91.7%–95.0% at 46,103–117,697 km (4 single cars) Datasets: AVILOO GmbH, Ny Teknik / Riddermarks Bil, Carla AB | 8 yrs / 100,000 mi, SoH below 70% (Polestar UK) |
| Xpeng G6 / P7 | G6 Standard Range 66 kWh: LFP. G6 Long Range (MY24, 92 kWh nominal): NMC. P7 86.2 kWh: NMC. | 2 | 99.0%–100.0% at 21,000–51,479 km (2 single cars) | 8 yrs / 100,000 mi (threshold not stated in UK leaflet) (XPENG UK) |
| NIO ET5 | 75 kWh: "LFP & NMC" (mixed). 100 kWh: NMC. | 2 | 84.0%–91.0% at 26,000–29,200 km (2 single cars) | 8 yrs / 160,000 km (Germany) (NIO Germany) |
| Volvo EX30 | 51 kWh: LFP. 69 kWh: NMC. | 2 | 97.4%–98.6% at 9,086–34,637 km (2 single cars) | 8 yrs / 100,000 mi, below 70% (Volvo Cars UK) |
| Dacia Spring | Electric 45 (2024–2025): NMC, 26.8 kWh nominal. Electric 70 (2026): LFP, 24.3 kWh nominal. | 5 | 91.0%–95.3% at 19,614–59,040 km (5 single cars) | 8 yrs / 100,000 mi, at least 75% capacity (Dacia UK) |
| Smart #1 | 66 kWh: NMC. 49 kWh: LFP. | 2 | 99.5%–100.0% at 1,800–27,500 km (2 single cars) | 8 yrs / 125,000 mi, below 70% of SoH at delivery (smart UK Automotive Ltd) |
LFP vs NMC: why chemistry matters when buying used
Many of these cars are sold with either an LFP (lithium iron phosphate) or an NMC (nickel manganese cobalt) battery depending on trim – so two cars of the same model can age differently. LFP is used in MG4 EV, MG5 EV, BYD Atto 3, BYD Dolphin, BYD Seal, GWM Ora 03 / Funky Cat, Xpeng G6 / P7, NIO ET5, Volvo EX30, Dacia Spring, Smart #1 (in at least one version; NIO's 75 kWh pack mixes LFP and NMC cells; specifications from EV Database – see each model page for the exact source).
There is no published multi-car LFP-vs-NMC comparison for Chinese brands yet. The clearest like-for-like evidence is from one model family in Sweden: in Carla's AVILOO-tested cars with more than 100,000 km, the Tesla Model 3 with CATL LFP cells averaged 93.3%, versus 91.5% for LG Chem and 89.8% / 88.2% for Panasonic NMC packs (Carla AB, 2026-07-08). Riddermarks found 94.7% for LFP Model Ys (avg 63,338 km) and 93.8% for LG-cell Model Ys (avg 68,403 km) (Ny Teknik / Riddermarks Bil). That is Tesla data, not proof for MG or BYD packs.
Before any SoH reading, fully charge the car. Battery management systems balance the cells during a full charge – MG says a full slow (AC) charge is the only way for its battery to reach its balanced "equalisation" state, and the MG4 shows "Please Slow-charge the Vehicle" if this has not been done for a while (MG Motor Europe). A reading taken after weeks of partial charging may be less meaningful.
Battery warranties (UK unless stated)
| Model | Battery warranty | Source (checked) |
|---|---|---|
| MG4 EV | MG UK (warranty statement for cars registered on/after 1 Sep 2019, online version dated 1 Jan 2025): vehicle 7 years / 80,000 miles; the lithium-ion high-voltage battery is listed at 96 months / 100,000 miles, and a capacity drop below 70% of the original value is treated as excessive loss (repaired, or the battery replaced with a new or remanufactured one). Private-hire/taxi EVs have a shorter vehicle warranty, but the statement says the HV battery "in all cases" has 8 years / 100,000 miles from 1 Jan 2025. Confirm the cover for the specific car (VIN, registration date) with MG. | MG Motor UK (2026-10-20) |
| MG ZS EV | MG UK (warranty statement for cars registered on/after 1 Sep 2019, online version dated 1 Jan 2025): vehicle 7 years / 80,000 miles; the lithium-ion high-voltage battery is listed at 96 months / 100,000 miles with capacity below 70% of original treated as excessive loss. Early ZS EVs (from 2019) may be close to or past the end of cover – confirm the start date and terms for the specific car with MG. | MG Motor UK (2026-10-20) |
| MG5 EV | MG UK (warranty statement, online version dated 1 Jan 2025): vehicle 7 years / 80,000 miles; HV battery listed at 96 months / 100,000 miles with capacity below 70% treated as excessive loss. Private-hire/taxi registered EVs: vehicle 3 years / 60,000 miles (80,000 miles if registered from 22 Mar 2024), HV battery 8 years / 100,000 miles from 1 Jan 2025 – check how the car was registered. | MG Motor UK (2026-10-20) |
| BYD Atto 3 | BYD (warranty manual for EEA, UK and Switzerland): power battery 8 years (96 months) or 250,000 km (155,350 miles), whichever comes first, with a minimum of 70% capacity retention (SOH ≥ 70%). Basic vehicle cover 6 years / 150,000 km. Gradual capacity loss above the 70% threshold is not covered. Confirm the terms for the specific car with BYD. | BYD (2026-10-20) |
| BYD Dolphin | BYD (warranty manual for EEA, UK and Switzerland): power battery 8 years (96 months) or 250,000 km (155,350 miles), whichever comes first, with a minimum of 70% capacity retention (SOH ≥ 70%). Basic vehicle cover 6 years / 150,000 km. Gradual capacity loss above the 70% threshold is not covered. Confirm the terms for the specific car with BYD. | BYD (2026-10-20) |
| BYD Seal | BYD (warranty manual for EEA, UK and Switzerland): power battery 8 years (96 months) or 250,000 km (155,350 miles), whichever comes first, with a minimum of 70% capacity retention (SOH ≥ 70%). Basic vehicle cover 6 years / 150,000 km. Gradual capacity loss above the 70% threshold is not covered. Confirm the terms for the specific car with BYD. | BYD (2026-10-20) |
| GWM Ora 03 / Funky Cat | GWM UK: traction battery 8 years or 100,000 miles against manufacturing defects; normal capacity degradation is not a defect, provided the measured SoH does not fall below 70% before the warranty expires. | GWM UK (2026-10-20) |
| Polestar 2 | Polestar UK: battery 8 years or 100,000 miles, whichever comes first; if SoH drops below 70% of original capacity within the first 8 years the battery is repaired or replaced at no cost. Vehicle warranty 3 years / 60,000 miles. | Polestar UK (2026-10-20) |
| Xpeng G6 / P7 | XPENG UK (G6 warranty leaflet): battery eight years or 100,000 miles, whichever comes first. The leaflet does not state the capacity threshold – ask XPENG what SoH level triggers a claim. | XPENG UK (2026-10-20) |
| NIO ET5 | NIO Germany: 8 years or 160,000 km on the NIO battery; ET5/ET5 Touring basic warranty 3 years or 90,000 km (extendable). Terms in other countries may differ. | NIO Germany (2026-10-20) |
| Volvo EX30 | Volvo UK: high-voltage battery 8 years or 100,000 miles from first delivery, whichever comes first; repairs to return capacity to at least 70% of original if SoH drops below 70% due to a manufacturing or material defect. Vehicle warranty 3 years / 60,000 miles. | Volvo Cars UK (2026-10-20) |
| Dacia Spring | Dacia UK: the Spring battery is guaranteed for 8 years or 100,000 miles and to retain at least 75% of its charge capacity at the end of that period. | Dacia UK (2026-10-20) |
| Smart #1 | smart UK (terms version 21 Mar 2025): high-voltage battery 8 years or 125,000 miles, whichever comes first; replacement if SoH falls below 70% of the SoH at delivery, measured by a smart Authorised Service Partner. HV core components 8 years / 100,000 miles; vehicle 3 years, unlimited mileage. | smart UK Automotive Ltd (2026-10-20) |
Two things stand out: BYD's distance limit (250,000 km) is much higher than the others, and Dacia guarantees 75% rather than 70%. Warranty terms change – always confirm with the manufacturer for the specific VIN.
How to check the battery on a Chinese EV
- Independent test: AVILOO lists FLASH-test support for MG4, MG5, ZS EV, BYD Atto 3/Dolphin/Seal, GWM Ora 03, Polestar 2, Xpeng G6/P7, Volvo EX30, Smart #1 and Dacia Spring. NIO was not listed when we checked (AVILOO GmbH).
- Manufacturer reports: Polestar workshops issue an official battery state-of-health certificate (Polestar / Brandt Personbilar AB Skövde); smart measures battery energy content for warranty claims (smart UK Automotive Ltd); MG service inspection reports can show an SoH figure, though owners report it moving by several points between services (MGEVs.com owner forum).
- Compare BMS and independent figures: AVILOO certificates show the car's own BMS value next to AVILOO's own calculation – on the published MG4, Atto 3 and Polestar 2 certificates they were within about 2 points (Car360, [2], AAA Auto).
- 12V battery (MG ZS EV): owners report repeated flat 12V batteries on some cars – ask whether software updates were done (MGEVs.com owner forum).
Data quality caveats
- Dealer certificates are for cars the dealer chose to sell – not a random sample.
- Several certificates are Australian cars (Carma); hot climates can age batteries differently from UK use.
- Some values are the car's own BMS reading rather than an independent calculation – each row says which.
- Owner reports (forums) are labelled n=1 and are the weakest evidence here.
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