We just ran into a problem with the battery in my wife's car. She started the car and went someplace and it worked fine. When she was ready to come home, the car did not start. I jumped if off and she drove home. I put the battery charger on it (30 Amp charger) for a 1/2 hour, then disconnected the charger and went to start the car, but it wouldn't crank at all. I had to jump it to start it to get it into the shop.
I pulled a battery cable thinking there must have been some kind of draw to take the battery down so quickly. Nothing! I pulled both cables, and put the charger back on for another 1/2 hour. After I removed the charger, I checked the voltage with my volt meter, I could watch the digital volt meter reading drop! In less then 2 minutes, the voltage went from 12.85 volts down to 10.75 volts! The 5 year battery developed a dead cell a day after the 5 year warranty expired!
I've been around a lot of car batteries before, this is the first battery I've ever seen die so quickly. Usually they give you a little warning, not this one, good one hour, dead the next.
It was kind of cool watching the battery voltage drop so fast. The new 5 year battery cost $64.79 out the door. Gene