My Jeeps been sitting for a couple months, got back did plugs coils and oil cause it was due anyway. Go to jump it, starts good, then after driving it around a couple minutes the check gauges light comes on and its reading 19V. Turned to off, dead, jumped it drove it around a couple minutes, same thing. Its got a brand new battery and alternator in it. Dont wanna mess anything up by overcharging, anyone know what might be the cause?

When you say it reads 19volts is that on the dash gage or another tester ?

Was reading that on the dash gauge. Jumped it again today, ran for a few minutes then started smoking. Should I get a battery tester? It is a brand new batter less then 3 months old.

Why is the battery going dead ? sometimes with a dead battery the charging voltage could go high what happens if you recharge the battery 1st or install a good battery ?

The regulator / rectifier on the alternator could be going bad. Lots of autoparts shops can test it.

Either that or the battery cables/clamps are shot. That happened to me, and the voltmeter would read 19v with all sorts of other electrical weirdness happening. No smoke, though. Have you actually verified the voltage with a multimeter across the battery terminals when it's running?

WHAT was smoking??

Bad grounds, it throws to ECU off and tries to maximize the alternator output. Happened to me, but not since replacing the engine and frame ground wires. No real harm done, the lights did not get brighter, I suspect it was the gauge only. A battery system can't rise to 19V instantaneously, it will boil the battery first. I now have a secondary voltmeter in a USB outlet.