Why Your Car's Battery May Be Draining Off While The Engine Is Off
A car's battery is supposed to maintain its power once the engine (and hence the electrical components of the car) is switched off. Sometimes, however, this doesn't happen, and current drain continues with the car switch off. This problem may be caused by different things such as:
Electrical Devices Running With the Engine Off
Just because the engine is off, it doesn't mean that its electrical systems are off too. Things like navigational systems, running radios and plugged in devices (such as smartphones) may continue draining off your battery even with the engine off.