Independent third-party charging curve testing for all four vehicles audited (Porsche Taycan, BYD Han EV, Xpeng G9, Hyundai IONIQ 6) across the full temperature range does not exist in the public domain as of March 2026.
The available data landscape: Porsche Taycan has partial European cold-weather data from multiple independent publications, showing approximately 120-140kW at 0C ambient — roughly 44-52% of the 270kW peak. This is the most documented vehicle in this audit. Hyundai IONIQ 6 cold-weather peak rate is estimated at approximately 140kW at 0C based on E-GMP platform characteristics — but this is an engineering inference, not a published measurement. Xpeng G9 has zero published cold-weather independent data. BYD Han EV cold-weather boost converter behaviour is completely undocumented.
The physics is clear: lithium-ion ion diffusion rates slow at lower temperatures following the Arrhenius equation, forcing the BMS to reduce charge current to prevent lithium plating. At 0C, diffusion is approximately 5-10x slower than at 25C depending on cell chemistry. Every vehicle in this audit will charge materially slower in winter than in summer. The question is how much slower — and no OEM has published the data that would allow a fleet operator to answer this for their specific deployment.
What would resolve it: A systematic independent test programme, ideally conducted by CATARC or a European equivalent, measuring 10-80% charge time at -20C, -10C, 0C, 10C, 25C, and 40C for each vehicle at representative charger power levels. This would require approximately 6 months and OEM cooperation to arrange appropriate test conditions. Without it, cold-climate fleet deployment of 800V vehicles carries material unquantified operational risk.
Last verified: March 2026. No comprehensive cold-weather charging data for Xpeng G9, Hyundai IONIQ 6, or BYD Han EV in public domain. Taycan partial data only. Status: OPEN.