How high is too high? And what causes it?

[dka99burb]

A while back, Brooklyn Tow noticed in another thread of mine that my voltage was running high. I ended up having to replace the batteries. I think it may have cooked them.. Now, with new batteries, I am measuring 14.5-14.6V across the posts when the truck is running. Is this too high? If so, what is common causes on these? Internal regulator on alt?

 

[ak diesel driver]

that's about right for a cold start but should drop down to the high 12s as it warms up

 

[dka99burb]

I will have to check it after warmed up. I havn't driven it much lately. Noticed a 'change' or increase in vibration that concerns me after all the talk about harmonic balancers lately. Plan to investigate after my next trip.

 

[3500GMC]

A If so, what is common causes on these? Internal regulator on alt?

Yeah pretty much. Things warm up and the electrical resistance goes up with it, thus your observed voltage drop.

 

[Edzzed]

Could also be that if the truck sits, the batteries discharge slightly so the initial higher voltage would be making up for that till the batteries charge is brought up. Mine does the same thing.

 

[Dieseldad97]

Sounds normal to me.