Many of us are using our cars less these days but are relying on the battery to power sevices which keep running even when the car is switched off, such as alarms, trackers and dash cams with parking modes. Even a clock could drain enough power over time to mean you hear the dreaded click when you try to start the engine.

In an ideal world we’d all keep our cars topped up using a mains-powered battery charger, but in reality not all of us have access to a plug.