What is the normal amount of car battery drain?
2 Answers
The normal range of car battery drain current is around 45 milliamperes. Some cars have dark current, which falls within the normal range of battery drain. The specific measurement steps for checking car battery drain with a multimeter are as follows: 1. Turn off the ignition switch, all possible electrical devices, and all doors. 2. Lock the car with the remote (for smart cars, keep the smart key more than 3 meters away from the car) and wait for 5-10 minutes to allow the vehicle to enter sleep mode. 3. Loosen the screw on the negative battery terminal. 4. Switch the digital multimeter to the current measurement mode (Note: Move the test leads to the corresponding jacks). 5. Connect the red test lead (to the negative terminal clamp) and the black test lead (to the negative terminal post). 6. Slowly move the negative terminal clamp and the red test lead upward together, completely separating them from the terminal post (at this point, the black test lead should be inside the clamp). 7. Observe the current value on the series ammeter. Generally, non-smart cars should show around 0.03A (30mA), and smart cars should show around 0.05A (50mA). If the value exceeds this significantly or even doubles, it indicates an abnormality.
I've been driving for over a decade and have considerable experience with battery drain. Normally, after the car is turned off, a battery drain within 50 milliamperes is acceptable. Higher readings may indicate issues like improperly turned-off electronics or circuit short circuits. I personally bought a multimeter to occasionally check: set the meter to the current measurement mode, disconnect the battery negative terminal and connect the meter, then wait a few minutes for the reading. For regular maintenance, I recommend periodically checking the battery status. If the drain is high, first inspect common trouble spots like the anti-theft system or radio to avoid breakdowns that could affect safety. Especially for car owners who have modified their audio systems, be extra cautious about loose wiring causing excessive drain. Maintaining battery health saves money and ensures peace of mind—don’t wait until it’s dead to panic.
