Died while flying down the freeway

[teetime4one]

My car died while on the freeway last month. I was in Illinois at the time. The first sign was a loss of power with electrical. The windows went down slowly and the windshield wipers crept across my windshield. I was alerted to the issue when the anti theft light and beep sounded on my stock stereo, which was off at the time. I pulled off the highway where the car rolled to a stop and died at a gas station. No power. No start. Sat for an hour waiting for a tow truck. I went into the car to grab a cold water and mindlessly turned the key in the ignition...the car stated. Drove 8 miles to the hotel I had found which was closest to the auto parts store. Car dies again. No power. An hour later I start the car and drive the 2 blocks to the auto parts store. They check the battery and see it's a bit low. I drive back to the hotel and wait for the alternator to come in the following morning. Wake up the next day and remove the alternator. Exchange and replace it with a new one. Drive away from town on the freeway. 25 miles later...power loss. Sit for an hour, car starts and drives fine. Drive another 10 miles to another auto parts store for a new battery. Car does great for 75 miles. Then, it happened again. Stopped at the same store (different location of course) and remove the alternator. Take it in to be tested. It's fine. Re-install and drive to a rental car store. Rent a car and leave my beloved 318ti there. Continue on my trip. 8 days later I return. Unlock the car. Start it and let it get up to temperature. Leave the keys under the seat with doors unlocked. I had arranged to have my car transported back to South Florida where it arrived without troubles.

Everything tests out fine. Replaced the alternator again. Same issue. Checked and replaced the main ground strap. Same issue. Took a volt meter to every wire in the engine compartment. Nothing unusual.

My car is still down. It only runs as long as these poor batteries will allow. It just seems to have a serious power draw somewhere...and, I can't find it.

Any ideas?