Nissan Repair: 1997 Sentra Charging problem - odd, alternator output, chubby hands

Question
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Followup To
Question -
I have a 1997 Sentra. At high revs / speeds over 60mph, the lights start to dim and the brake and battery dash lights will flicker on and off...just brief flashes. Around town it charges fine.

I've checked the wiring and grounds. I think it's the alternator...but I have never seen the "lights dimming on revving" or the odd brake and battery light flashes.
Answer -
Ken,

Check your alternator output at between 1200 rpms and 3000 rpms.  It should be about 14.2 max and if it jumps you have found your problem.  


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Hi Von,

Thanks for the help. At 2000rpm it is charging and system is at 14.1 volts.
Above 2500-3000 rpm the voltage (at the battery) just drops to about 7 volts. As soon as it drops to idle, it charges.

I had the battery tested....it's OK.

So does it look like the voltage reg? I guess it's time to grease up my chubby hands and squeeze in there and replace the alternator and belt?

Let me know what you think,
And again, Thank You!

Ken

Answer
Ken,

It is the alternator.  If you could get the parts you could probably replace the regulator that is inside the alternaotor.  But, it is usually more trouble than it is worth since you would need a new brush kit too.  And, if something gets messed up in the process there is no warranty on the work.  I would go with a rebuilt alternator.