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Used electric car: battery warranty, SoH and what to ask

Part of the Guide Electro-mobile batteriesAre you choosing a car? The battery chemistry of specific models can be found in catalogue of electric cars.

The battery is the only thing you can't judge with your eye when you buy a used electric car, and it's half the value of a car.

What covers the guarantee

The market standard is 8 years or 160 000 km (what happens first) with a guarantee that capacity will not fall below 70 % (somewhere 65-75 %). Watch out for details: the guarantee refers to a fall below the border and to defects, not to a "normal" degradation above it; it passes with the car to another owner; and it can limit the failure of the service conditions.

SoH: Let it measure, not say

State of Health the seller likes to "estimate." They want to measure: independent test (e.g. Aviloo - premium driving test, flash test from OBD), extract from the manufacturer's service, or at least an OBD reader with an app for a given platform. Indicative reading: 3 years: 90-95 % = healthy, below 88% want an explanation (taxi? DC-only? permanent 100 %?). 6 years: 85-92 % is a normal zone.

Questions about the seller

How was the car charged (home AC vs. DC-only fleet)? What was the daily charging limit? Service history and BMS updates? U LFP: calibrated to 100 %? And always: SoH test as purchase condition - they don't scare a serious salesman.

Which chemistry and battery has a specific model, find in Catalogue - for the used ones, be aware that the same model could have different batteries in different years.