When do you need to replace an alternator in a car?
When you have tested the charging system of a car fitted with an alternator , and the checks in How to test a car battery point to a fault in the voltage regulator , make sure that you need to replace it. The fault may be elsewhere.
How much does it cost to replace an alternator voltage regulator?
A new alternator voltage regulator will cost you anywhere from $40 to $140 for parts, heavily dependent on the make/model of vehicle and whether using OEM or aftermarket parts. The cost of parts doesn’t sound so bad, but since most voltage regulators are housed inside the alternator, expect to pay around $140 to $240 in labor.
How can you tell if an alternator regulator is faulty?
A simple way to check the alternator is to start the engine and connect a voltmeter across the battery terminals. If it registers battery voltage only, the fault is in the alternator or its wiring, or in a field isolating relay if fitted. If it registers an excessive charge (15 volts or more) the regulator is faulty and you should replace it.
What should my alternator voltage be at rest?
To use a multimeter for testing, set the knob to a number greater than 15 on the DCV (DC volts) section. A fully charged battery at rest should measure between 12.6 and 13.2 volts. With the engine running, the alternator must exceed that voltage at the battery.
What causes high voltage in alternator?
You should get 0.5 to 2 volts higher than base voltage. If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty. Other potential problems are a faulty voltage regulator or a problem in the charging system wiring.
What is the regulated voltage from an alternator?
Normal readings should be around 14 volts for a so-called 12-volt system. This is because the voltage output of the alternator must greater than the battery voltage or current will not flow into the battery, which on its own should produce about 12.8 volts when fully charged.
How much voltage to “excite” an alternator?
The maximum output from your alternator should be regulated to between 14.1 and 14.4 volts DC. The voltage regulator’s job is to supply voltage to the battery when it’s not at the nominal level.
How much voltage does an alternator put out?
This means that while the voltage of most car batteries is 12 volts, an alternator will typically output anywhere between 13 and a half and 15 volts of electricity.
If the alternator has gone bad then they have found the reason for your failed battery; it makes no sense to install a new battery when the shop knows it will fail again in short order …because the alternator is not doing its job. This becomes an issue when the battery has a warranty …as in it’s warranted for 36 months and lasts 12.
Why does the battery light come on after the alternator is replaced?
This would make the Battery Light come on. It is also possible that there is a problem with the fusible link or the alternator fuse for the charging system.
How long does an alternator and battery last?
As a battery ages it loses its ability to hold a charge, as a rule of thumb a battery will last about three to four years. If the battery is fairly new you will need to start the engine by jump starting or charging the battery using a battery charger. Once the engine is running test the alternator in the charging system.
What does it mean when your alternator is not charging?
If the alternator is not charging the battery, you will have a red “ALT” or “charge” sign on your dashboard. This means that your battery is no longer being supplemented for power by the alternator. You will need to recheck the wiring because the light could also be faulty.
This would make the Battery Light come on. It is also possible that there is a problem with the fusible link or the alternator fuse for the charging system.
What should I do if my alternator fails?
If the battery is fairly new you will need to start the engine by jump starting or charging the battery using a battery charger. Once the engine is running test the alternator in the charging system. If the alternator fails, replace it with a new or rebuilt unit and re-test system, if the alternator tests ok proceed to the next step.
As a battery ages it loses its ability to hold a charge, as a rule of thumb a battery will last about three to four years. If the battery is fairly new you will need to start the engine by jump starting or charging the battery using a battery charger. Once the engine is running test the alternator in the charging system.
If the alternator is not charging the battery, you will have a red “ALT” or “charge” sign on your dashboard. This means that your battery is no longer being supplemented for power by the alternator. You will need to recheck the wiring because the light could also be faulty.