Top Reasons Why Your Car Battery Becomes Completely Drained

If your car battery does not get fully charged with engine running, but it can be charged with external charger, it is likely that the car has a fault in charging system. If the battery gets drained when the car is not in use, then there are multiple possibilities. This may even mean that when the car is not in use some battery power is draining out. This may cause the car not to start the next time it is used. The reasons can be one of the followings.

1. Any of the aftermarket fitments has a short circuit, which can be a stereo system, central locking system installed after the car was bought or any other electrical gadget. This will be fine as long as the engine is running since the alternator will supply power when engine is running. Once the engine is switched off the device will start to drain power from battery. Slowly over few hours it will fully drain the battery. The time taken will depend on the fault in the device, sometimes it drains battery very fast too.

2. The wiring in the car can have short circuit which can cause battery to drain. This can be due to original car writing or due to wiring done to fit an aftermarket accessory. In some cases it has been observed that the wiring has been improperly connected in an attempt to fit an accessory, and this has caused a short circuit. Sometimes after doing accident repair work grommets or bushes protecting the wiring from touching the sharp edges on car body are missing. However this cannot be entirely blamed on the repair work, some are dislodged due to the accident itself and the mechanic is unaware of it as it might be out of view. These edges slowly cut in to the wires and cause short circuit, thereby draining the battery. An example is the opening in car body where the wires from engine come in to the passenger cabin to the fuse box. This opening has sharp edges which can cut the wires over a period of time. It is important to note that a major short circuit in wiring will be blowing the fuse of the circuit in which the short circuit is happening. This will prevent any incidents of car catching fire, but in case of extra fitments of accessory it depends on how well the wiring has been done. If the wiring has been routed in an incorrect way then there are chances of car catching fire also. So always get these kind of work done at a reliable place.

3. In some cases small lights can be staying on inside the car due to faults in switches. The switches I am referring to are not the ones that are operated by us but the ones that are concealed near the door catches of cars. You might have observed the light inside a refrigerator which comes on when door is opened, and goes off when door is closed. Tip: to observe this you can watch it go of just before the door is fully shut. Same happens in the boot of a car, there is a light that comes on when the boot is open. If the switch that operates this light, which is fixed near the catch of the boot lid is defective, this light cam stay on. That means even if the lid of the boot is closed the light stays on inside but it is not visible from outside. When the car is parked this light will slowly drain the battery over many hours until the battery is fully dead. The same can happen with cars equipped with glove box light, which works similarly.

4. Everyone has a friend who has wires in his car bitten by rats. While this more often than not, causes malfunctions and breakdowns, this can also cause short circuits also and result in battery drain. This happens when the rat bits off wires partially and the insulation has been removed by the bite. In such case the wires might touch the car body and get shorted. They can also come in contact with other similarly bitten off wires that is nearby.