What should an alternator charge 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.

What voltage is too low for an alternator?

If you see a reading of more than 0.2 volts, it means trouble. Ideally, the voltage drop across any connection should be zero, or less than 0.1 volts. Check for voltage drops at the positive and negative battery cable connections, the alternator BAT+ power connection and the engine ground strap(s).

What should my idle voltage be?

Additionally, once the engine is running, the battery should be receiving a charge from the alternator. Because of this, the multimeter should read between 13.8 and 14.5 volts when the engine is at idle.

What is normal alternator voltage output?

A good alternator should maintain battery voltage between 13.9 and 14.8 volts (14.2 is optimum). Even worst-case, with all accessories turned on, there should be at least 13 volts at the battery.

How many amps should my alternator be at idle?

Typically you can find alternators up to about 100A with the internal regulator and 1-wire output feed, higher than 100A and you need to start looking into a separate stand-alone V-regulator as the heat generated by a high-Amp alternator's diode bridge and the v-regulator itself would greatly shorten the life of that ...

At idle speed the alternator was not working.

What RPM does an alternator start charging?

These rpm, along with the pulley ratio, directly affect an alternator's performance and life expectancy. 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.

At what RPM does the alternator charge the battery?

Alternator may not generate sufficient charging voltage until alternator speed is greater than about 2000 RPM. Typically, alternators have their full output rated at 6000 RPM but can continue to spin up to 12,000 RPM or more without any additional increase in output.

What is a good alternator reading?

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.

What is a bad alternator reading?

Look for an ideal alternator reading of around 12.6. Start the car, and look for a reading of between 14.2 and 14.7. A reading of over 14.7 means the battery is being overcharged, while a reading under 14.2 means the alternator is undercharging the battery.

Is 14.7 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. Above 14.5 volts charging voltage, batteries have a greatly increased tendency to release excessive acidic vapors, hydrogen gas, and to corrode things around the battery.

Why does my alternator not charge at idle?

The most common reason an alternator is not charging the battery is due to worn carbon brushes or a damaged alternator itself. It can also be caused by a blown fuse or bad wirings. If your serpentine belt snapped off, the alternator will, of course not charge then either.

Is 13 volts enough for alternator?

The voltage should read a minimum of 13 volts. A good alternator should put out between **13.5-14.5 volts. Stress test the alternator - Place a load on the alternator by turning on the headlights, the radio and the air conditioning. The voltage should remain high with these circuits on.

What causes an alternator to drop voltage?

In turn, the alternator needs to replenish the battery and provide the power for the vehicle loads through the charging cables and connections. If the street is too narrow to carry the current, it shows up in measurable "voltage drop" or loss.

Is 13v too low for alternator?

For some alternators, it's normal to see as low as 13 volts. For some, a constant 13.6 volts is an indication of a problem. For others, it's normal to see as high as 16 volts for long stretches. Still, it's perfectly normal for others to see the alternator not charge at all intermittently.

What is normal charging voltage?

Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts. If you don't have a multimeter to tell you the voltage of your battery, you can do a test of your electrical system by starting the car and turning on the headlights.

How long does an alternator take to charge a battery at idle?

Basically, at idle you can probably get 80 amps out of your alternator. You can charge a flat battery to 80 percent full in about 2 hours, so long as you alternator can manage produce around 14 volts at the battery terminals this whole time.

How long does it take for an alternator to charge a battery at idle?

Faster speeds generate more RPMs, so your battery will recharge faster at speeds of 55 MPH or higher. It takes most vehicles about 30 minutes of driving at highway speeds to fully recharge the battery. Keep in mind that 30 minutes is an average.

Does revving car charge battery?

Yes, revving the engine will still charge the battery faster.

How long should you leave a car running to charge the battery?

Remember: After you've done a jump start, you'll need to keep the vehicle's engine running for around 30 minutes to allow the alternator time to charge the battery sufficiently.

What should a 12v alternator charge at?

A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery. If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery.

What should a 12-volt battery read when fully charged?

A fully charged battery will typically display a voltmeter reading of about 12.6 to 12.8 volts. If your voltmeter is showing a voltage anywhere between 12.4 and 12.8, that means your battery is in good shape. Any voltage above 12.9 volts is a good indicator that your battery has excessive voltage.

When testing an alternator minimum required output what is an acceptable reading?

Ideally, the voltmeter should read less than 0.2 volts. If the alternator output circuit and ground circuits test good (voltage drop less than 0.2 volts) and the vehicle has a history of repeated alternator failures due to burned out diodes, check for a shorted indicator light terminal.

Can an alternator test good but still be bad?

Tools Required. If you have a newer battery but your car won't start, you may have a bad alternator. If you're tempted to test an alternator by disconnecting the negative battery cable, don't do it. A good alternator may indeed keep the engine running without the negative cable, but this was never a good test.