Car Battery Draining Quickly? How to Check for and Find the Causes of a Current Leak in Your Car!
Are you experiencing a rapid battery drain? It's possible the problem is a current leak in your car. In this video, I'll show you how to check for a current leak and find the cause!
Link to the UNI-T UT213C current clamp meter from Aliexpress - https://s.click.aliexpress.com/e/_DEf...
Link to the multimeter from Aliexpress - https://s.click.aliexpress.com/e/_DDY...
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The car I'll be using to demonstrate the current leak detection is a BMW e38 740. The customer experienced a problem with the car starting poorly. He realized the battery was draining quickly, so he replaced it with a new one. However, the replacement didn't solve the problem.
How do I find a current leak in a car? First, I always do a cursory inspection of the car to identify any additional faulty devices. Most often, the problem is an improper connection.
Next, we need a tool to measure the current leak. This can be either a multimeter, which measures current, or a current clamp meter. I used to always use a multimeter, but it's not very convenient, so I bought a current clamp meter from AliExpress - http://got.by/51tktt . The only drawback of a current clamp meter is that if there's a bundle of wires, you have to fluff them up to take a measurement.
On this car model, after turning off the car and closing all the doors, the electronics still run for about 16 minutes. Therefore, we need to wait this time to ensure the current leak measurement is accurate. I also opened all the doors, the trunk, and locked the trunk to prevent the lights from tripping. We need access to the battery, which in my case is in the trunk. I also unscrewed the fuse box to access all the wires. First, I'll show you how to check for current leakage in a car using a multimeter. Set the multimeter to measure current. Place one of the probes under the ground terminal to ensure contact with the car body. Unscrew the negative battery terminal, but don't remove it. Next, touch the negative terminal with the second probe, while simultaneously trying to lift the terminal to maintain continuity and maintain electrical contact between the ground wire and the battery terminal. The terminal shouldn't touch the probe. We see that the leakage current is 290 mA.
With a current clamp meter, finding the current leakage is much easier. We don't need to remove the terminal. Simply set the current clamp to DC current measurement mode, reset the reading, and attach it to the wire. The current clamp shows that the leakage current matches the multimeter reading.
Now we move on to finding the source of the current drain. Using the current clamp meter, we go through all the wires and look for the leak. Next, we trace the wire to the fuse box and determine what exactly it controls. If you don't have a diagram, you can find one online. In my case, it's a 10 mA fuse that controls the phone.
If you only have a multimeter, the current leak detection pattern is slightly different. Remove the fuses from the fuse box one by one and measure the battery terminal. If the leak disappears, the problem is related to that fuse.
After identifying the fuse, we move on to solving the problem. The car's factory phone was plugged in, which was causing the current leak. At first, I thought I'd solve the problem by removing the fuse from the fuse box, but upon checking, I noticed that the amplifier was also connected to that fuse. I finally started digging further and discovered that the phone itself can be turned off, either system-wide or by disconnecting the phone cable from the jack. After doing this, the increased current leakage disappeared. Ultimately, the cause was quite simple: the customer wasn't using their car's features correctly.
Current leakage is considered normal at readings up to 70 mA. Since cars are now equipped with a fair amount of electronics, such a discharge current can occur. A leakage current of 20-30 mA is considered ideal.
As you can see, a current leak in a car can be caused by trivial things, which can drain the battery and prevent the car from starting. Maintain your car, install additional equipment correctly, and you won't have any problems. If you have any questions, ask them in the comments to this video!
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