Starters and alternators

Starters and alternators are much more reliable on today's automobiles than the ones that were available Just a few years ago.

This does not mean that you will experience complete trouble-free operation from these two extremely important components. So just in case here is some information on these engine starting car parts.

Starters and alternators work in conjunction with the vehicle battery to make sure you have the required tools necessary to start your engine.

When you turn your cars ignition to the start position, a small amount of current will flow from the battery to a starter solenoid.

The motor then extends the starter drive that meshes with the flywheel mounted on the rear of the engines crankshaft.

As the crankshaft turns the engine is rotated through it’s four strokes.

At the correct time the ignition system will fire the spark plug to ignite the air fuel mixture. After a couple successful ignition cycles, the engine will begin to rotate on its own without the need of the starter motor.

At this point, the driver will release the ignition key, which will automatically settle to the on but not crank position. The solenoid is turned off and the starter drive retracts automatically.

Powering starters and alternators

Drivers should be aware of how old their battery is because in most cases batteries will not last more than five years.

The length of your battery life will be determined by your driving characteristics and in some cases your location (weather).

While the starter is rotating the crankshaft it uses a lot of electrical power.

The amount of amps used can be measured and tested with a diagnostic machine known as a vat-40 (or equivalent) which is a specialized tester for these 2 circuits.

Engine cranking tends to lower the amount of available power in your cars battery. Therefore, the alternator is needed to recharge the battery so that the engine will start in the future.

It also provides electrical power for the ignition system, air conditioner, heater, cell phone chargers, lights, radio, ipod car accessories, and all electrical related accessories when the engine is running.

The charging system includes an AC generator, better known as an alternator.

Also included in the charging system would be a voltage regulator, malfunction indicator light, and both heavy duty and light-duty wiring.

The belt driven alternator converts mechanical energy into electrical energy.

When the alternator is turning slow, and a large amount of accessories are in the on position the alternator may put out less than the vehicle requires.

At this point, the vehicle is in a negative state of charge and is actually pulling power from the batteries.

In most cases, the negative state of charge condition is short term and compensated by a driving cycle where the positive state of charge, recovers and upholds the health of the battery.

Engine starting and battery charging

If your driving habits include extremely short trips with long periods of idling, Battery life could be affected in a negative way.

Vehicles that are used very little, coupled with very short driving cycles can experience dead batteries much more often than people with long commutes.

In some cases, it would be wise to use a battery maintenance charger on vehicles that do a lot of sitting.

These trickle chargers are usually inexpensive and even solar powered in some cases. The battery tender is a top 10 seller on amazon at the time of this writing. This is a good way to extend the life of your battery and alternator.


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For more car related electrical information including theory and testing visit the page about automotive electrical


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