While driving the 300 SEL yesterday, first the A/C shutoff, then the ABS light came on, then the car just shut down totally and would not start again. There be enough of power that the windows would work, radio would turn on, but the engine would not crank.

Towed it to my Tech and he said that the there was a faulty circuit in the battery so he replaced it. No big deal was within warranty.

Took the car out today and it did it all over again after driving for 25 minutes. Could it be the alternator? Is it possible that the alternator was charging properly at the shop when the car was colder so the Tech did not notice, but once warmed up, the alternator or voltage regulator stopped working. Could it be another bad battery?

Help appreciated? Have to tow it again.