Took the truck into a shop they said the alternator is bad. I put a new one on....but I'm only reading 13.7??? Volt at the battery with the truck running. I was thinking it should be 14+ volts with truck running!
Could someone offer some help?

Thanks!

 

Shud be in the neighborhood of 14.5V unless you have a crap load of shiznit (heavy load) running. Take it to the shop that supplied it, have them check it and replace it. DO NOT let them tell you it's OK, something isn't right.

Cheers!

Mike

 

There are variables.
1. The regulation is temperature compensated. Voltage goes up as temperature goes down.
2. As a battery ages, the voltage goes up. If you force a constant 14.5V on a new, good battery, it'll cook off electrolyte.
3. If a good battery has been deeply discharged, it'll take awhile for the voltage to get to 14V. It's not failing, it's accepting the charge.

Battery voltage is just one piece of information. Actual charge current is another useful piece of information. Battery age and condition, and environment also help.

One piece of the puzzle often missed is drive belt condition. Serpentine belts don't usually scream and shred to notify us that they are dying like V belts do. They do wear, however, and if they are worn to the limit they'll slip, limiting alternator output.

Gates will send you a free wear gauge for the asking.

Gates Belt Wear Gauge For Serpentine Belts | Gates Corporation