Hi all,
I always wondered how a car battery is able to charge cell phones, radio, dashboard and all other things that requiere electricity, and not need to to be recharged for a couple years. Why does it not die out sooner? Can someone please on how it’s able to achieve this curious feat?
Thanks!
In: Engineering
Every car has an alternator. An alternator generates electricity. The alternator in your car is spun up by the engine and directly charges your car battery. Over time the battery will charge less and less because the more it is used the less total charge it can hold, referred to as degradation. If the alternator in our car dies, the battery will run out within a few days or even hours and the car will not be drivable.
A car battery will recharge itself while you’re driving around using the alternator in your car (basically an electric generator). It uses up a significant portion of its charge every time you turn over the starter motor but this is replenished within seconds/ minutes.
Your car battery is only used when the engine is not running, and principally it exists to deliver the amperage necessary to power the high-torque electric starter motor that cranks over the engine, which starts the self sustaining combustion cycle.
After the engine is started, the combustion cycle drives what is called an engine accessory; these are all the components driven by the belts off the front of the engine. Most of these components are pumps: the AC condenser pump, power steering pump, water pump – for the engine cooling system, sometimes a smog pump for emissions…
One such accessory is the alternator. This is a device that produces an alternating current, and it produces more than enough power to both recharge the battery, and run the entire electrical system of the car – most importantly the ignition system, but also the very energy hungry headlights. Alternators are self-regulating, in that they produce nominal power output once they spin at a minimum speed, and from there will lower or raise their output to compensate for changes in their rotational speed. This is why, when using jumper cables to start another car, it doesn’t help to rev the engine of the supplier car.
Some of this power produced by the alternator will be used to recharge the battery. The power in the battery is stored chemically, and those reactions are reversible to a point. The average life of a battery that sees regular use is around 7 years.
Cars that won’t start have an old battery that can’t deliver the amperage necessary to turn the starter motor adequately. If a running car dies due to an electrical failure, seemingly cured by a jump, the alternator itself has failed, and the vehicle is actually just running off the battery. You can get a few miles out of just a battery.
The car battery’s main job is to provide power to the starter to start the car. While it can charge things inside the car, or power things in the car such as the headlights or the dash console screens, this is not done for any length of time other than when the car engine is turned off. The battery is recharged every time you drive the car or run the engine by the alternator. The engine generates power and the alternator uses that power to recharge the battery. This happens repeatedly as you drive. The battery is being drained and recharged over and over again.
The battery inside a car is really only used to start the car, and the alternator is what runs the car after the initial start up and also charges the battery as the vehicle runs, so thats why they last so long without charging and are also able to charge all of your mobile devices.
Car batteries are constantly recharged by the engine via the alternator. All a car battery really needs to do is provide enough electricity for the car to start and the engine does the rest.
Your car battery holds several hundred amps of electricity to start your car and keep it running.
So the car battery is hooked up to your starter motor. When you turn the key to start the motor kicks on and spins the engine. The starter then disengages. Your alternator is hooked up to the engine with a belt, it charges the battery, ALL of your electrical systems on your car are hooked to the battery. The voltage off the alternator is very noisy and will damage the sensitive electronics in your car. When the voltage drops on the battery your alternator engages and starts charging, if your on a long road trip or there isn’t a high electric load on the batteries your alternator will actually disengage and free spin so it won’t overcharge the battery. If the voltage regulator fails your battery will actually overcharge and start to boil and can explode. Once the load increases or the voltage on the battery drops the alternator engages and starts charging again.
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