Why does a Car Battery Lose Charge When Not in Use?

Does your car battery keep on losing charge even when not in use? Below are some of the possible reasons that you should evaluate for you to get to the particular cause of car battery charge leakage.


Charging system problem

This is the most common cause for car batteries losing charge when not in use. A faulty charging system destroys the battery’s general performance after a while, causing it to charge faster than the initial speed but lose the charge faster as well. You can easily check if your battery is in a good condition by using a voltmeter and replace it if it is already destroyed.

If you want to avoid the dead battery trouble, get a battery charger and maintainer. The best battery tender for car storage ensures that you don’t over-charge your car battery and maintains the battery voltage when you have not used the vehicle for long.

Bad battery terminals connection and wiring

Even though it is difficult to examine the battery’s connection due to the fact that it is normally fitted into tight compartments in the engine bay, you can remove a few plastic covers to access the wiring. Check the vehicles’ handbook for guidance then check if the terminals are corroded or loose, clean them using a sand-paper/wire brush or tighten them accordingly.

Forgetting to turn off the headlights/interior lights

Depending on how long the lights stay on, leaving the headlights or the interior lights on will automatically drain your battery even when your car is off. Some advanced cars are designed to produce a certain sound which alerts you when you forget to switch the lights off but if yours doesn’t, then you should always double check.

If you are planning on investing in another car, enquire about the latest model of the car that automatically switches the lights off when the ignition is turned off.

Failing to fully close the door/trunk

Another possible cause is forgetting to fully close the doors and the trunk of your vehicle. Even though these two do not drain the battery, the interior lights will continue to light when you don’t lock the doors or the trunk.

Electronic devices remaining plugged in

Leaving any electronic accessory like cell phones plugged in can discharge your battery even when the engine is off. That’s why it is always advisable to unplug all the devices before exiting your vehicle to preserve your battery charge.

Parasitic drain

Another possible reason that can lead to your battery losing charge even when you have grounded the car is parasitic drain which includes; security alarms, clocks, and radio presets. Relay switches that remain on even when the vehicle engine is off can drain your battery hence you should ensure that you switch them off when you are not using the car.

Bad alternator diodes

A perfect diode only allows the current flow in one direction while a bad one leaks the current because it can flow in the opposite direction. This may keep the charging circuit on even after the car’s engine is off thus discharging the battery.

Old batteries

Batteries that have been drained continuously over a long time may not be able to hold full charge hence it goes dead even when the car is off. Taking care of your car’s battery will increase its longevity hence allowing it to stay in a perfect condition for long. Avoid exposing the car to extremely cold weather if you want to prevent the battery from freezing over.

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