Does Running A Car Charge The Battery. To be sure your car will always start. When driving the engine delivers more power which means it may charge the battery quicker than simply letting the engine idle.
Since the battery sometimes gets hot during recharging so you need to stop charging it for some time until it gets to a normal temperature to start charging again. Yes the car will charge at idle and as molgrips says its not good to run the car at idle especially in from cold start in cold weather. The time taken to fully discharge the car battery depends on the batterys condition and the type of audio components you are using with your car.
You wont fully recharge your battery by going for a drive idling the engine or going for a short stop-start trip.
Generally a few minutes - 5 or 10 of driving time where the RPMs get high enough to raise the alternator output to charge the battery effectively to replace the energy used for starting. If your car does start let it run for a few minutes to help charge the battery further. In the same way the radio will drain your battery. It is quite safe to charge the battery while the terminals are still connected.
