I recently bought a Peugot Ion electric vehicle, 3 years old but with very low mileage. I am generally delighted with the car but disappointed with the battery performance so did some checks to discover it was only charging to about 80% of its advertised capacity, and seems to have 2 cells (of 88) performing much worse than the others. I think this would indicate a defective battery which should be fixed under the 5 year battery warranty. The problem is, all batteries suffer degradation in normal use, and nowhere does the warranty say exactly what constitutes a defective battery.

Is there any 'case law' regarding what an EV battery warranty should cover? I have not spoken to Peugot yet - wanted to get my facts straight first.