The car has an automatic transmission and has gone around 40,000 miles. It has been draining batteries for no apparent reason. I went to the dealership so that they would solve this problem but they didn't find out what causes this. I have already replaced several batteries. They just die out without any warning, so when I go to start the car and put the key in the ignition, I cannot get it out as the battery died. I'm very concerned to drive the car on any longer distance as I might get stranded somewhere. Do you have any idea what could cause this?
The most likely causes are either a parasitic drain on the battery or a faulty alternator. The battery is basically just a storage device which must be constantly charged by the alternator. A battery that is partially discharged often will meet and early demise. If the alternator is OK, the next thing to do is check for a parasitic draw. Something inside the vehicle that is getting left or somehow drawing too much current, will eventually wear down the battery. A professional can check for this by placing an ohmmeter in series with the negative battery cable and checking the reading. I suggest you have your vehicle inspected firsthand to determine the true cause of the draining battery and extent of the problem. The team at YourMechanic is an excellent option since we make house calls.