Why parked electric cars can gradually lose battery charge

An electric vehicle can lose charge while parked because locking it does not switch off every system. Battery checks, maintaining the smaller 12-volt battery, connected services and features such as cabin climate control or vehicle surveillance can all use electricity, so losses may build up over a long trip away.

The amount varies with the car, its settings, the weather and how often apps wake it. Tesla says a Model 3 may lose about 1 per cent daily, while Recurrent reports sleeping Teslas can lose 0.1 to 0.3 per cent a day and cars running power-hungry features may lose several per cent. Cold weather can also change the range estimate without an equivalent drop in stored energy; for longer storage, Tesla advises keeping the Model 3 plugged in and at around 50 per cent charge.