I have a 90 Legend with a slight problem.
Well ive put in a new battery and a new alternator but periodically the battery will die and needs to be jumped. Sometimes when i brake the voltage drops real low. I have replaced the battery once and the alternator 3 times since i have the car in a course of a year. After i changed the battery i havent had any problems for a month. I could leave my little 12volt heater running without the car on and itd start fine. Now it is happening again.
Is there something that would go bad to drain the battery like a reverse effect from the alternator?

Also what cause a car to overheat besides a thermostat or anything to do with the fluid levels. Thanks