When I run at highway speed the volts sits at 14, when I slow down to go in town it drops to halfway between 14 and 8, this started a few weeks ago. I also get a strong smell of eggs, thinking acid boiling. I checked both batteries and they check good when unhooked from truck, also they are not running warm. thinking maybe poor battery. any thoughts. altenator has 125000 km since rebuild. Batteries are 7 years old. and are 650 CCA

 

Changed alternator tonight, everything is good now. 14 volts all the time

 

Nice to hear that you got it solved.

I usually had good results with just changing the brushes in the alternator.

They can be bought at fostertruck.com for the stock alt.

 

Yes, rotten egg smell is battery. Might want to make sure they're both in tip top condition after being charged with that problem alternator.