Batterie Problem I think?

[ekam]

Most garages should have a battery tester (instead of a simple voltmeter) to test for weak/dead cells. What make is the battery? Perhaps you just need to top it up with distilled water? If it's still in warranty you can try to claim it.

EDIT - actually 12.4v sounds about right...

http://www.buchanan1.net/lead_acid.shtml
http://www.aa1car.com/library/battery_runs_down.htm

[mikehkang]

Sorry to potentially confuse you but my voltage reading from the cigarette socket reads 12.2 volts. (It is around 88 degrees now.)
The battery is about 18 months old.
I have no issue with the battery.

To me, your situation is a puzzle indeed because you can cold start but have an issue AFTER driving for a while. One would think that you would be net charging whiling driving.

Good luck.

[redeye280z]

That's what is weird about it after driving the battery should be well charged because the alternator is working fine.

[mikehkang]

If you suspect the battery, have it checked out.
Here in my area, I can go to an Autozone and they will check it for free.

I will tell you later what the voltage reading from the cigarette lighter is when I am driving.
You can compare it against your figure.