Does running air-conditioning with my car’s ignition off affect the battery life?

Does running air-conditioning with my car’s ignition off affect the battery life?

The ability to install an air-conditioning system within a motor vehicle has been around since 1940. Before this, a fact that would have offered little comfort to a generation of South African children loaded into the rear seat of their parent’s hatchback ahead of an annual cross-Karoo summer family holiday. A hundredth game of I-spy completed, who could forget the moment that lowering the car’s window for relief from the heat within the vehicle was met with even warmer outside air, but also the wrath of the driver as the “ambience” of the cabin was disturbed?

An altogether more commonplace standard feature in most new vehicles, an air-conditioning system works by channelling refrigerated air towards any number of vents positioned around the car’s cabin. Including a compressor, a condenser and an evaporator, an air-conditioning unit is a particularly power-hungry component that relies on the workings of a belt-driven alternator that’s mated with the car’s running engine to operate effectively. Without the engine running, a hamstrung climate control system can only draw power from the next available source of energy, your car’s battery.

While it may initially feel as though your car’s air-conditioning system is still working after the ignition is switched off, without a steady supply of power from the running engine, this system can only offer already cooled air from within its pipework, after which there’s little benefit to keeping it operational. A climate control system can, in turn, deplete the energy reserves of a modern car battery within 30 minutes.

Included within the operating system of most modern vehicles is an audible warning to the driver once functions like the infotainment system (including radio) and air-conditioning are proving too much of a burden for the car’s battery. These warnings are usually followed by an automatic powering-down of these functions to preserve the battery, maintaining enough charge for this item to perform its primary task of firing the engine to life.


Best Camping Gear for Overlanding Bikers in South Africa