so i was driving to work in the morning and my idiot light chymed check gauges...i looked at the voltage gauge and it dropped to zero.. i pulled over shut it down, then re started it went to 14 then dropped to 12 an to 0..so i drove to work.. after work i started it up and walla it was charging at 14v all the way home..i pulled the alt out and took it to oreilly auto parts we tested it 3 times and it kept reg at 14.3v ...im very lost
so my question is would old batt make it do this????? any and all help is greatly appreciated..

 

oh ya sry 2001 ram 2500 5.9 cummins 2wd 5spd

 

Check/clean your battery terminals lately?

 

Battery terminals to start. Then it sounds like the brushes in the alternator are starting to hang up. Mine did that a couple times and I just cleaned and replaced them. Cheap repair.

http://www.fostertruck.com/alternators.htm