I'm attempting to figure out why my car isn't starting. I've reseated all the grounds and made sure the ground connections were clean and bare. I've cleaned the battery terminals and clamps with a wire brush as there was some corrosion on the terminals. I charged the battery two days ago due to abundant corrosion and a lack of voltage on the battery. It was reading 11.8V. I charged it up to 12.8V with a battery charger that plugs into the house. I didn't attempt to restart the car at that point. Today, two days later, the battery is at 11.8V again and will not turn the starter. I measure the amperage drain on the battery and it's .06A, which for the Porsche 944, is within tolerance. It should be around .05.-07 Amps. Obviously, a 60mA drain over 2 days shouldn't drain a full Volt off the battery. I charged the battery up again today to 12.3V. However, when I turn on the headlights and the blower motor, (not engaging the starter), the voltage on the battery plummeted to 8-9V within 10-15 seconds of doing so. From what I've gathered online, shouldn't the battery only be seeing a .1-.2 voltage drop when the headlights are on? Why is the battery acting this way? What could be going on? Thanks.