Japan Proposes Battery-Life Gauge for EVs

Regulators in Japan plan to require that future electric cars be fitted with a gauge that indicates how much charge they can hold after extended use, The Nikkei reports.

The storage capacity of a lithium-ion battery slowly diminishes with repeated charging, as cellphone owners can attest. The proposal from Japan’s Ministry of Economy, Trade and Industry would dictate that EV instrument panel include a display that shows battery capacity relative to the date of purchase.

Nissan Motor Co. already offers such a gauge in its Leaf electric sedan, but many other EVs don’t, The Nikkei notes.

The ministry points out that creating a benchmark for measuring battery capacity will help determine the value of used batteries and support a market for refurbished units.