Title, why can we drive for hours and hours on end, with headlights, radio, a/c, etc. (besides stopping for gas, bathroom breaks) But when we leave a light on for as much as an hour, the car battery will pretty much die instantly.
In: Engineering
To start a car requires a big burst of energy, but it only needs it for a very short time, as once an engine is running it is also being used to run a component called an alternator, which recharges the battery.
So while the engine is running, all of the electrics are being powered by the alternator, and the battery is not really needed.
Leave the lights on without the engine running however and the battery gets drained, without having the alternator running to recharge it. Run them for too long and you won’t leave enough stored electricity to provide the burst of energy needed to start the engine.
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