What is the normal leakage current in milliamperes for a car?
3 Answers
The normal value for car leakage current is generally around 40 milliamperes. Causes of car leakage: battery drain due to unswitched electrical appliances when parking, self-discharge and power loss caused by short circuit or oxidation shedding of battery plates. Leakage caused by grounding of automotive electrical appliances, wiring harnesses, sensors, controllers, actuators and other electronic components and circuits. Methods to find car leakage: check whether the battery voltage and power generation are normal and whether the battery terminals are severely rusted. If the static current is too large, it can be checked by pulling out fuses and relays one by one and observing the change in static current.
As someone with years of driving experience, I've encountered similar issues. Normally, a safe leakage current for cars is below 20 to 50 milliamperes; anything higher could indicate a problem. My car typically tested around 30 milliamperes, which is common. If it's higher, you should check for leaks in the wiring, battery, or installed equipment, like improperly installed audio systems. After parking and turning off the engine, if the current is too high, the battery can drain within a few days, making it troublesome to start the car. I recommend using a multimeter to test every six months—turn off all electrical devices, wait half an hour, then measure. Keeping the current at a low level can extend the battery's lifespan.
I always pay attention to these small details when driving, afraid that the car might not start. The normal leakage current should be controlled within 50 milliamperes, neither too low nor too high. Previously, the leakage was high, and the battery was drained in less than a week, so I had to get it fixed. It turned out to be a short circuit caused by aging wiring. Normally, don’t tamper with the circuit randomly; if you’ve added things like GPS, check the insulation. The battery itself can also leak, and there’s a big difference between new and old batteries—new batteries are more reliable when kept at a low level. If there’s still significant leakage after the engine is off and no equipment is working, there might be a major issue affecting driving safety.
