ee Mechanical Help
All the problems and possible solutions detailed below are provided by the experienced automotive mechanical engineers who carry out our vehicle inspections. The problems covered can be common to most vehicles but the list is by no means exhaustive. If your particular mechanical problem is not answered below ask our engineers for mechanical assistance here.
How to test a car alternator.
Car Alternator.
The car alternator is used to charge the car battery when the engine is running and is a perishable item on a car which can fail after many miles of motoring. When the alternator fails usually the battery light will come on on the display to indicate the battery is no longer charging.
Alternator on petrol cars.
On a petrol car the alternator is more crucial than on a diesel car as the battery provides the power for the spark therefore if a battery is not charging the battery will eventually flatten and no spark will be generated causing engine failure.
Alternator on diesel Cars.
Although the diesel car needs a battery for electrical items such as lights, indicators, radio, fans, rear demist, windscreen wipers...etc, once the engine is running it does not need electrical power to keep running. In the event of an alternator failure you would not be stranded by a engine shut down but safety would be compromised by loss of signalling and lights.
Testing your alternator.
Testing your alternator is a quick and simple. You don't need to remove the alternator to carry out a test and it doesn't require expensive tools.
Click to view large image
What you will need is a volt meter or multi meter. They are very simple to use, and can be purchased in many retailers for as little as £5.
Alternator Test.
Make sure all the electrical items mentioned above are turned off and then have someone rev the car's engine to a fast idle (say 2000-2500 rpm).
Set the Voltmeter to DC and place the red lead of the voltmeter on the positive terminal and black lead on the negative terminal of the battery.
At a fast idle, the voltage should read approximately 14 volts (13.5 to 14.4). Although your battery will be likely 12 volt the alternator has to generate a larger voltage to overcome the internal resistance of the battery. The current needed to recharge the battery would not flow if the alternator output was the same as that of the battery.
If the reading on the volt meter is less than 12 volts then you may have a failed alternator.
One last alternator check.
Turn on all the electrical items. Now have someone rev up the engine again and check the voltmeter. It should still be reading around 14 volts. If it reads lower than 13 volts the chances are that the alternator is faulty and will need to be replaced befor
http://wheretobuycarsfrom.com/how_to_test_car_alternator.asp
All the problems and possible solutions detailed below are provided by the experienced automotive mechanical engineers who carry out our vehicle inspections. The problems covered can be common to most vehicles but the list is by no means exhaustive. If your particular mechanical problem is not answered below ask our engineers for mechanical assistance here.
How to test a car alternator.
Car Alternator.
The car alternator is used to charge the car battery when the engine is running and is a perishable item on a car which can fail after many miles of motoring. When the alternator fails usually the battery light will come on on the display to indicate the battery is no longer charging.
Alternator on petrol cars.
On a petrol car the alternator is more crucial than on a diesel car as the battery provides the power for the spark therefore if a battery is not charging the battery will eventually flatten and no spark will be generated causing engine failure.
Alternator on diesel Cars.
Although the diesel car needs a battery for electrical items such as lights, indicators, radio, fans, rear demist, windscreen wipers...etc, once the engine is running it does not need electrical power to keep running. In the event of an alternator failure you would not be stranded by a engine shut down but safety would be compromised by loss of signalling and lights.
Testing your alternator.
Testing your alternator is a quick and simple. You don't need to remove the alternator to carry out a test and it doesn't require expensive tools.
Click to view large image
What you will need is a volt meter or multi meter. They are very simple to use, and can be purchased in many retailers for as little as £5.
Alternator Test.
Make sure all the electrical items mentioned above are turned off and then have someone rev the car's engine to a fast idle (say 2000-2500 rpm).
Set the Voltmeter to DC and place the red lead of the voltmeter on the positive terminal and black lead on the negative terminal of the battery.
At a fast idle, the voltage should read approximately 14 volts (13.5 to 14.4). Although your battery will be likely 12 volt the alternator has to generate a larger voltage to overcome the internal resistance of the battery. The current needed to recharge the battery would not flow if the alternator output was the same as that of the battery.
If the reading on the volt meter is less than 12 volts then you may have a failed alternator.
One last alternator check.
Turn on all the electrical items. Now have someone rev up the engine again and check the voltmeter. It should still be reading around 14 volts. If it reads lower than 13 volts the chances are that the alternator is faulty and will need to be replaced befor
http://wheretobuycarsfrom.com/how_to_test_car_alternator.asp
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