I have a 99 RX300 that suddenly wouldn't start. The battery was dead. So I took it to a parts store and had it charged and tested. Battery was fine. So I put it back in the car, it started with no problem, and drove it to the parts store and had the alternator checked. The alternator was providing only 10v so the battery was slowly draining. I replaced the alternator with a recertified one. My mistake was I didn't go back and check the voltage after replacing the alternator and now after 2 weeks, the car won't start again. I'm hoping it's just a bad alternator but if not, what else could it be?