How to Repair Battery Parasitic Drain

Let's see how to diagnose the parasitic drain on your vehicle's battery. First, ensure that the battery is healthy; set the multimeter to Volt-DC and connect the red lead to the positive terminal and the black lead to the negative terminal. A charged and healthy battery should have a voltage of 12V. Modern cars have computers that remain active even after the ignition is turned off, so you need to wait for all these systems to deactivate after turning off the vehicle: this can take up to 45 minutes on newer models. Set the multimeter for the test by turning the dial to DC Amps, disconnect the negative cable and connect the black lead of the multimeter to it, and the red lead to the disconnected negative cable. This way, all the current leaving the battery to power the car's circuits must pass through the multimeter. Below 50 mA is normal. Above 50 mA indicates a problem: a component is consuming too much power. Keep the multimeter connected and remove the fuses one by one (both in the engine compartment and in the cabin) and check the multimeter each time. If the current measured drops drastically below 50 mA when a fuse is removed, you have found the culprit! Now you need to find the faulty component. The number one suspects are aftermarket components, which are often installed poorly. Also, look for loose, oxidised, or damaged connectors, lights that may be left on, exposed wires; if possible, check using the wiring diagram.