testing alternator output

[rippinitup7 10+ year member]

is there any type of test i can do on my own to test the output of my alternator while installed on the vehicle? i just bought a 165 amp alternator and i want to make sure its working to its full potential. i still get some dimming w/ headlights on and system going, but i only had time to upgrade my postive cable, so the negative is still stock. could this alone be whats bogging my system down?

does these numbers sound reasonable for my setup:

12.56 volts -- off

13.78 volts -- engine running, radio off

12.03 volts (lowest it would drop to) -- engine running, radio on at near full potential

i guess things will only improve getting the negative cable done, but was just curious is everything is working like it should.

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[johnecon2001 5,000+ posts]

Aside from testing the voltage on your own, there isn't much you can do unless you have a clamp meter. Not exactly typical consumer gear.

The negative cables are almost more important than the positive. Stop being a lazy *** and finish the job.

 

[disturbedfuel15 10+ year member]

Stop being a lazy *** and finish the job.

What he said. Oh, and if you are poor and can't afford more cable, still stop being a lazy *** and steal some so you can finish the job //content.invisioncic.com/y282845/emoticons/furious.gif.fc81ca146dbff91fede3ed290dbc4f4c.gif