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
Your cars engine recharges the battery when the engine is running.
A battery can store only so much power. Many batteries (like in your phone) use relatively little power at one time, because your phone doesn’t have moving parts (except maybe a vibration function).
A car battery needs to deliver a huge burst of power all at once- enough to turn your car engine over until the engine fires up and then uses fuel to continue running.
The battery can power your engine itself if you wanted … for about 30 seconds. Then it would be flat.
Once the motor starts, the energy comes from the petrol burning. That energy then partly flows back into the battery to recharge it, ready for next time.
This uses something called an alternator
If your alternator fails, the battery will eventually go flat and you won’t be able to start your car.
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.
Latest Answers