Users' questions

What is the normal output of an alternator?

What is the normal output of an alternator?

The voltage should read a minimum of 13 volts. A good alternator should put out between **13.5-14.5 volts.

What is the maximum output of an alternator?

An alternator has a normal range of operation. Most alternators need to spin at about 2,400 rpm at idle, have their maximum output above 6,000 rpm, and should never exceed 18,000 rpm.

How do I check the max output of my alternator?

Turn on all the electrical equipment in the car: lights, stereo, wipers and everything else you can. Let the engine idle at around 1200 rpm. Check your car’s manual or parts manual to see what your alternator’s maximum amperage should be. The amp reading on your meter should be near the maximum output.

What is a good reading for an alternator?

A good alternator should produce about 13.5 to 14.5 volts with the engine idling. If the voltage reading is low (12.5 volts or less), it indicates a charging problem but does not tell you what’s causing it.

Is 14.8 volts too high for alternator?

To fully charge in reasonable times, alternator output must be 14.2 V to 14.5 V as measured right across the battery posts. 14.8 would start to be a worry (there might be liquid or corrosion on the battery) and 15 volts would be a real concern, but 14.6 is fine. Less than 14.3 would be a “weak” alternator or regulator.

How can I tell if my alternator is draining my battery?

To do a quick alternator drain power check using your digital multimeter, go to the section Bad Alternator Diode Test below. Then, if your alternator passes the test, do a battery check using a hydrometer tool as described in the Car Battery Hydrometer Test section.

What causes an alternator to put out High 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 causes an alternator to put out low voltage?

Poor ground connections are an often-overlooked cause of low charging output and alternator failure. Voltage drops on the positive side of the charging circuit can cause undercharging. Voltage drops on the negative side can cause overcharging.

Is 15 volts too high for alternator?

To answer your question, yes, 15 volts is too high. Most car alternators that charge your battery after every start and provide power while the engine is running are usually regulated to between 13 and 14.0 volts. It will increase in power with increasing voltage.

How many volts should my alternator put out at idle?

Most alternators that are charging properly should produce a voltage of about 13.8 to 14.2 volts at idle with the lights and accessories off.

Can a alternator drain a battery?

Even while your car is off, your battery provides power to things like the clock, the radio, and the alarm system. These things shouldn’t have a major impact on your battery. But when the engine is off, the alternator can’t recharge the battery, allowing little electrical mishaps to drain your battery entirely.