On a 2001 GTP with 31,000 miles that I purchased two years ago, I keep having the issue of the battery showing 9 volts or less.
I drive the car only occasionally. Each time I do, I take a fully charged battery (either a Sears Diehard Platinum or Optima redtop) from another car and install it in the GTP. It starts right up and I drive it anywhere from 20 to 30 miles.
I monitor the Aero Force Interceptor gauge at the start of the drive and it reads around 13 volts. I usually drive at highways speeds.
Upon returning home at low speeds of less than 20mph and letting the car idle in the driveway, I notice the headlights and interior lights dimming. Then the antilock brake light flickers on and off. The Interceptor gauge reads as low as 9 volts.
If I shut off the engine, the car will not restart.
After hooking up a Sears charger to the battery, the car will restart after a few minutes of recharging.
The gauge read 10 volts or so, and will continue to drop.
If I install the battery in another one of my GP's, the engine will start right up.
Also, I have made sure the battery terminals are free of corrosion (I have never seen any corrosion on any of the GP's I have ever owned)
Note: There is no aftermarket stereo in the car.
Also note: Car has many modifications, one being a trunk mounted pump to cool the supercharger.
What could be causing the voltage to drop so drastically?
Alternator? As far as I know, the original one is in the car.
Wiring from alternator to battery?
Battery cables?
