Car doesn't start after sitting overnight

Hello, I am having problems with my car not starting in the morning. I have replaced the battery twice and taken it to a mechanic a several times now. They claim the alternator is fine. I have also hooked up a multimeter and the voltage across the battery while engine is running is ~14.2 which I think I satisfactory to keep up the charge. I checked the drain while the car is off by wiring the multimeter in series with the negative side of the battery. The draw was about 30mAmps and I set in the car about an hour just to make sure it didn't fluctuate.

The battery voltage does decrease substantially overnight. I cannot think of were the current is flowing if NOT into the rest of the charge. Any advice would be greatly appreciated.

Thank you,

Bejan