I have an 02 Suburban w/ 5.3L motor.

How do you check the output voltage of the Bosch Alternator?

I do have a VoltMeter.

Dash guage shows 13.9-14 Volts, but I would like to see what the alternator is putting out.


Thanks,
Scott

 

Start the car and put your voltmeter on the battery. It should be reading 14.4 volts. Another way to check it is to test the battery voltage with the car off then compare it to the voltage when the car is on. One last way to check it is to disconnect the battery after the car is started and see if it'll keep itself running and/or check the voltage at the battery cables. Make sure they don't toutch.

 

This isn't a good idea in modern vehicles.

First reason is the brushes for the rotor inside the alternator are exicited form the battery voltage ... remove the battery and no excitation for the brushes and the alternator won't work then the vehicle stalls.

Second you can damage the regulator in the alternator since it requires the impedance of the battery to monitor how much current to supply. If the battery is missing then the regulator will put out maximum current and likely burn out the alternator.

Third is you will have no current path from negative to positive if you remove a cable from the battery and the vehicle will stall.

 

IF it's such a bad idea and it will stall if I take the battery out, then why can I do it on all my vehicles and nothing is damaged and it will still run?

 

The battery isn't the only path to ground; the vehicle won't stall. However, electronic voltage regulators will not be happy if you disconnect the battery. They may continue to work, or the diodes may punch through.

I don't think most people would recommend disconnecting the battery in a modern car. The electronics are just too fragile.

Regards,

David

 

Thank you all for your input. I will give it a try.

Scott