How to Detect Car Battery Leakage?
2 Answers
Wait for 5 to 10 minutes in the locked state to allow the car to enter a dormant mode. Use a wrench to loosen it, then gently pry open the fastening block with a flat-head screwdriver, at which point you can directly pull out the negative terminal. Connect the red probe of the multimeter to the vehicle's grounding wire and the black probe to the negative terminal of the battery. If the reading falls within the normal range, it indicates that the car battery is functioning normally.
I often check for battery drain myself as someone who enjoys tinkering with cars, and the method is actually quite simple. First, ensure the car is completely off—all lights, AC, and audio are turned off, doors locked—then wait five minutes to let it settle. Next, disconnect the negative battery cable, set a digital multimeter to the milliampere range, and connect the probes in series between the positive battery terminal and the positive cable. Normal leakage current should be minimal, such as below 50mA; if the reading is high, say over 100mA, there's a drain issue needing repair. At this point, you can pull fuses one by one from the fuse box to see where the current drops, pinpointing the culprit—maybe a trunk light or aftermarket device is secretly draining power. Ignoring a drain will drastically shorten battery life, so regular checks on battery health and securing wiring can prevent many headaches.
