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My newly purchased jeep stalled out at a red light when I had an FM Transmitter and dash light plugged into cigarette outlets. Since then, it takes a little longer to start when it sits over a few hours. I have been afraid to touch cigarette outlets since. amigo mechanic changed cam sensor, crank sensor, ignition coil, and plugs a few days ago, but the car still takes a little time to start when it sits.

Took it to auto zone for a battery test and the voltage is 15.1 volts when on per their voltmeter. I was told by worker & I read everywhere that this was overcharged and too high, and could definitely cause some symptoms I've seen. So I basically called the car dealer and said fix this right now. When I dropped the car off, I noticed the dashboard battery gauge has 15 almost right in the middle of the high and low... and now I feel like an idiot as my car sits in the lot!!

Is the 15 volts normal and the internet was wrong?!? or is that battery gauge something different?
4439964
 

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It should be right around 14 when running. Fully charged battery should be 12.6 with engine off.

If it's cranking over longer before it starts, the fuel pump is probably leaking down as it sits. Try turning the key to ON a few times without stating it. Then see if it starts up quicker. The fuel pump primes for a few seconds each time the key is turned ON.
 

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Best way to check the battery voltage is with a good DVM. 14.3 +-running. The gauges are basically idiot lights with needles.
 

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The voltage gauge is indicating a flat battery. Did you get the battery properly load tested? If the battery is weak the computer could be increasing the charge voltage to try and put some charge into it.

If that happens, the voltage of the battery will be raised just after switching the engine off. Which could give a high reading. Batteries should be left to settle for a while after charging so they will show a more accurate open circuit voltage.

Start with a proper load test of the battery. If the battery is bad replace it.
 

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All of the information above is correct.

P.S.:
My Zurich code reader has battery/alternator test functions that were pretty handy. It reads the voltage that the engine computer sees.
Not to mention, that is is also helpful in seeing live data (temp., O2 sensor voltages, etc.) and clearing some of the flaky TJ codes that pop up every so often.
 
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