Question to the Department for Transport:

To ask the Secretary of State for Transport, what estimate his Department has made of the average decline in battery efficiency in each year of a passenger vehicle's life.

The Department has not made an estimate of the average decline in battery efficiency in each year of a passenger vehicle’s life. The Faraday Institute is the independent research vehicle for the Industrial Strategy Challenge Fund’s £246m Faraday Battery Challenge. Improving our understanding of the performance of lithium ion batteries over time in electrified vehicles is an important part of the Faraday Institute’s role. That is why of the Institute’s four ‘Fast Start’ projects, with up to £42 million in funding, two will look at improving our understanding of batteries: extending battery life and battery systems modelling.

In order for a car to be eligible to receive the Government’s Plug-in Car Grant of up to £4,500 off the cost of a new vehicle, the manufacturer must provide a minimum five year warranty on the battery and electric drive train, and extra evidence of battery performance to show reasonable performance after three years of use.