What.. alternates by them to recharge the battery? How is it recharging? In a gas car? While its off? I feel like an idiot!
In: Engineering
They’re called alternators because they produce alternating current (AC). They have a pulley on one end with a belt that allows it to turn the engine’s mechanical energy into electric energy
An alternator is basically an electric generator. When you move a conductor through a magnetic field it causes or “induces” an electric current in the conductor. This is called “electromagnetic induction”. Similarly when you pass a current through a conductor it creates a magnetic field around the conductor. This phenomenon can be used to take electric current and create movement such as with an electric motor, or to take movement and create electricity such as with an electric generator.
The gas car takes the movement created by the gasoline engine and uses it to turn an electric generator to make “alternating current” or AC, which is then converted to “direct current” or DC to charge the battery. It does this while the motor is running, not when it is turned off.
Alternators, make AC current, hence they are called alternators. A rectifier is used to convert the current to DV current to charge the battery and provide electrical power for the cars system. The alternator is driven by a pulley from the engine.
They don’t do any charging while the engine is off. The engine is what gives it the kinetic energy that it turns into electricity.
In the old days, they used DC generators but those generators couldn’t output the amount of current that modern cars need to operate everything. Alternators can output a lot of current and do it fairly efficiently. There is a high current rectifier inside the alternator that converts the alternating current into sort of a pulsed direct current that your car needs.
Nothing “alternates”, an alternator generates alternating current as opposed to direct current, that’s where the name comes from.
Then that AC current is passed through rectifiers to change it to the DC/direct current that your vehicle’s systems use.
Electric motors work in both directions! If you add electricity they turn, but if you turn them, they make electricity! They are electric generators!
A car’s engine spins more than just the tires. It spins the alternator and a few other things too. So when you are driving, the alternator spins and fills the battery up with electricity.
When starting a car, it uses the battery to run a motor (the starter) that gets the engine spinning fast enough for the internal combustion to take over. Once the car is running it needs electricity for other things (spark plugs, radio, GPS, lights etc). The battery wouldn’t have enough charge to last very long. The alternator is a generator, it converts the spinning energy of the engine into electricity, which is fed back into the battery.
Think of a car’s electrical system in 2 different “Modes”. You have Starting, and Continuing.
Starting –
This is when you input your key and turn the ignition. What is happening here is the Battery is using its 12v volts to turn the starter. The starter is an electric motor with a gear on the end. That gear is directly connected to your flywheel. The flywheel is a giant plate of metal with geared teeth on the outside circumference. Think of a 12lb plate with the outside toothed. This plate, is directly connected to the output shaft of the engine, so as the engine pumps power, the flywheel turns. In manual cars this flywheel is butted against what’s called a clutch plate. When you push in the clutch, the pads (just like brakes) slow both down to the point that they are both moving at the same speed and the gears can shift. On automatics, they have what’s called a, “Torque converter” that does the same thing.
Continuing –
This is the mode your car uses 98.6% of the time. In this mode, your battery is useless. It’s charged back to capacity, but otherwise, the power is diverted away from the battery. The alternator provides all the electrical production the car requires.
Get it? A battery in a car is used for 1 thing, and only 1 thing…
To provide the necessary “juice” to crank that starter.
It’s a generator that’s connected by pulleys to your engine which is gasoline powered. It charges the battery, which powers the spark plugs and everything else electric in your car. The battery’s main load is to power the starter which initiates the engines turning, any power draw after that is pretty small and allows the cars battery to top up.
The alternator does not power anything when the car is off. The alternator changes the rotation of the engine into electricity.
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