Disclaimer I don't right now have exact numbers as I'm posting from my work break.

my battery, when not under a load will read at the normal 12.4ish or whatever is normal. As soon as the engine starts running it shoots up to about 15 and I watch as the battery gauge starts to lower the longer I drive. Lowest I've gotten to is maybe 14.5 or less.
the problem is all my driving is very short distances and less than 20 minutes running time so I haven't seen how far down at goes. If I restart not too long after shutting off the voltage stays around wherever it came down to but If I waif a couple hours it goes back to around 15.
not noticing any funky smells indicating overcharging. Battery is new and alt supposedly tested good at oreilkys and aap when I had to replace battery.
any ideas or maybe this is actually normal lol

 

14.5V is normal for when the engine is running. 12V wouldn't charge the battery.

 

Yep, what he said.

 

Thanks for the replies however I am aware of where the voltage should be, my concern is that it jumps so high to 15. Not only that but it slowly trickles down while the engine runs.

 

Still normal. You need to put a DVOM on it to compare with the factory gauge.

 

Remember also that lead-acid batteries in cold weather need more voltage to charge. The regulator should be temperature compensated, so it'd be normal to see higher readings in the winter than the summer.

 

He's in Florida, so I doubt cold weather is a factor.

But it's true there is a temperature correction factor to charging voltages. As a general rule it takes about 2 volts above the resting voltage of a battery to reach a full charge, so somewhere around 14.5 volts or more is normal.

BUT, need to add 0.5 volts at 50°, and a full point at 0°, this is because of increased internal resistance as temperature goes down. All published voltage specs are based on 77° F, in truly cold weather 16+ volts is not out of line.

In high temperatures above 77° the opposite is also true, charging voltages need to be corrected (reduced) from the standard figures.