This Is How You Can Diagnose A Dead Car Battery


Everyone who has a car is very careful with its services but accidentally leaving an interior light or parking light on overnight can kill the battery and create a big problem in the morning. However, knowing what to do next, like jumping or replacing a battery doesn’t seem to be a big challenge. Usually jumping works but older batteries can cause all kind of issues in the end as well. Therefore, it is better to know if your car battery still has life in it or not.

New Battery

If your car has a new battery, a jumpstart is needed to get you going. For this solution, you will need a jumper cable or a standalone jump kept in the truck. Since the battery is healthy, it will receive power easily from the other battery to charge up properly. You can do this by parking and turning off the car while keeping the charged battery next to the dead one. Open the hood of both the cars, and take the jumper cables out. Make sure to protect your hands and eyes in case an accident occurs.

Connect one end of the red jumper cable to the red post of the dead battery and then connect the other end of the red cable to the red post of the charged battery. Similarly, connect the black post of the charged battery and the other end to an unpainted metal part in the dead battery. This will ground the circuit to avoid any sparking. Now you can start the car with the charged battery and let it run for 5 to 10 minutes. After that, start the car with the dead battery. If it starts, let it run for at least 20 minutes before starting driving. To completely charge the battery you can drive for at least 5 miles. While taking off the battery cables, remove them in the reverse order in which they were attached.

Old Battery

In the case of an old and dead battery, you will need a new one. But before that, it is necessary to determine if it is your battery which is dead and there is no other issue. A dead battery can be identified easily if there are no lights or cranking when the car is turned on. Another sign is that the engine cranks but not starts. There can be other issues, but mostly it’s the battery. You can use the jumpstart method here, but sometimes the battery is too damaged to charge on a jumpstart. In this case, you can take the car for a free battery testing and buy a new one if needed.

What Can Drain Your Car’s Battery

Mostly the vehicles draw battery current when the key is off because of the clock, internal memory of engine computers, body-control modules, and radio presets. These devices draw a minimal amount of current, and fifty milliamps are considered a safe upper limit for this. You can measure the car’s off current using a multimeter with 10 or 20 amp capacity. Unplug any power-draining cables from the lighter socket like a cell phone charger or GPS. Once you determine the current drain, you can reduce the meter’s scale to an appropriate low scale. Some devices like alarms and automatic-dimming lights draw a substantial amount up to 20 minutes after they are deactivated so if the reading is high, wait for sometime to see if it changes.

How To Control The Excessive Current Drawn From The Battery

Once you have determined that there is excessive current being drawn from the battery, you need to find from where. With the help of the schematic diagram, disconnect each device on the circuit one by one and check the meter. When the milliamp reading starts dropping you know that you have found the problem. The devices which mostly consume a considerable amount of current are car alarms, stereos, and proximity keys.

The issue of draining of battery through devices can arrive if you leave the car parked for several weeks without starting it. Therefore if you are going away on vacation, make sure you unplug all the devices which can be the reason to kill your battery.