How to find out battery current leaks with battery drain tests
The problem of overdrawn and worn out batteries is not limited to the battery charging system and lousy quality battery. Current leakage in the car's electrical circuit can also make the car battery run out quickly.
For example, the battery has been replaced with a new one but in the next day, it is no longer strong enough to start the engine. Your car wont start clicking noise. This condition means there is a leakage of an electric current inside the car's electrical circuit.
So the electric current stored in the battery is continuously wasted and comes out useless. This leaky current causes the car battery to come up short and wear out quickly.
There are two kinds of checking methods that we can do to find out the battery leakage current problems. This method is called Battery drain tests.
- I. Parasitic load battery test
- II. Surface discharge battery test
The article below will show you on how to do the battery drain test. But before testing the battery, you need to prepare several items such as:
- Digital Multimeter
- Hand tools (open-end wrench or ring)
- Gloves
I. Parasitic load battery test
A parasitic load is an unwanted load that draws current when the ignition switch is turned to OFF. This problem is typically reported as "car battery drains overnight while vehicle was parked".
Check for a parasitic load as follows:
- Get a digital multimeter and set it to the DC ampere position
- Turn off all electrical devices in the car such as air conditioners, lights, and close all doors tightly (for security, open the window to prevent the door from locking itself during inspection)
- Turn the ignition key to the LOCK or OFF position
- Disconnect the battery negative terminal cable
- Connect the multimeter positive lead to the negative terminal head of the battery
-
Connect the multimeter negative lead to the battery negative terminal cable
as shown in the image below
-
Read the value of the electric current that flows and pay attention to its
conditions in the table below
Measurement results Battery condition 0,02 - 0,07 Ampere Normal > 0,1 Ampere There was a leakage current
Wait 2-3 minutes after removing the battery's negative terminal to ensure that all electrical components are completely off before we do the parasitic load tests.
Some of electrical devices generally create parasitic loads that continue to flow electric current even though the ignition key is in the OFF position. Still, they don't drain the car battery excessively—for example, the alarm and security system.
Read more:
- How to test a car battery with multimeter
- My car battery low voltage, what this mean?
- How to test an alternator without multimeter?
II. Surface discharge battery test
Surface discharge occurs due to a small electric current flowing between the two battery terminal heads (positive and negative) through the battery case surface. Generally, surface discharge occurs when the battery head is slightly damp, wet, and dirty (lots of scale or dust).
Check for surface discharge as follows:
- Turn the ignition key switch to the OFF position, turn off the lights, the air conditioner, and close all car doors.
- Prepare a digital multimeter and set it to the DC volt position
- Connect the multimeter negative wire to the negative terminal head of the battery
-
Connect the positive multimeter cable to the top surface of the battery box
as shown in the image below
- Check the car battery leakage voltage
- Read the value of the voltage that flows. If the voltage that flows is more than 0.5 volts, clean the battery box's surface, especially around the battery terminal's head, and let it dry.