Q: What Are the Top 5 Things That Will Change Your Car Battery?

There are many reasons why a car battery will drain, but it depends on the year of your vehicle. If you are driving an older vehicle, it could be something like an aftermarket alarm system, a poorly installed aftermarket stereo system or a clock in the car staying on. It could also be as simple as a light staying on in the glove box or the trunk. There are many ways to check for a battery drain.

To check if the trunk light is staying on, put your hand on the trunk lid in the area where the bulb is. If you feel the heat from the bulb being on, unplug it or remove the bulb. Sometimes it could also be that the alternator may not be charging the battery enough and it acts as if something is draining the battery.

If you have a vehicle manufactured since 2000, then you could be having computer issues. Vehicles today are getting more and more sophisticated with technology and have more onboard computers. In the late 1990s and early 2000s, vehicles had only one computer; now a vehicle could have over 30 different modules that stay on even after you shut off your vehicle. These modules often draw a few mA (milliamps) because of something called KAM (Keep Alive Memory). Whether it’s the clock in the radio or the last known position of the memory mirrors, these tiny amounts of KAM-induced current typically will only add up to 20 or 30 mA at most. That means the vehicle can sit parked for days, or even a few weeks, without any problems of excessive battery drain that might prevent starting. As long as the vehicle is driven periodically for the alternator to recharge the battery, there is no problem.

All of these computers are supposed to go to sleep or shut down completely after a certain amount of time. Sometimes they don’t and they need to be reprogrammed to do so. If you leave accessories plugged into your cigarette lighter such as a phone charger or a GPS, these could also drain down your battery. I recommend that you unplug them when you are not in the vehicle for many reasons other than battery issues; I have seen cell phones melt down in a vehicle and cause fires inside the interior.

The easiest way to check on what is draining your battery is to use an automotive meter, connect it in series with the positive side of the battery, and have the settings on amps. There should be a reading of less than 1 amp, depending on the year of the vehicle and what make it is. Now start removing fuses one by one till the amps drop to nothing. Once they drop to nothing, then you have found the circuit that is the issue. However, you should only be doing this if you have extensive knowledge about cars and trucks. Otherwise, you should have a certified technician look at the vehicle to remedy the situation for you and replace the battery if needed.