I've been trying to hunt down a major electrical gremlin in my car, but things just seem to keep getting worse.

When trying to start the car, it is 100% dead. No lights, to door chime, dead. The battery will charge to 13 volts on a trickle charger but when I connect it to the car the reading drops to near 0. Yesterday I hooked it up after cleaning some electrical connections and noticed a smell, sizzle sound, and heat coming from the battery (and immediately disconnected it).

So far I have cleaned up the battery wires at both ends, including major grounds, starter solenoid connections, alternator connections, and replaced the alternator ground cable. Checked, cleaned and replaced any suspect connections to the 25 Amp fuse and the positive distribution block on the drivers fender. I've also replaced the ignition switch, and cleaned the connections at the ICM (Ignition control module/power stage).

I'm not sure where to go from here. Replace both battery cables? Replace the starter and solenoid? I'm operating on the assumption that this must be an issue with the main power system of the car, as opposed to say a grounded oxygen sensor or speed sensor wire, since battery voltage drops as soon as the battery is connected.

Please help! What is the vampire that is sucking the life out of my car? I want to drive and visit my 90yo grandmother for Thanksgiving!