My wife has a 2010 FFH that's having intermittent 12-Volt Battery problems (starting problems).
One night she left the headlights on while she was out and ran the battery down. When she went to start it, it wouldn't, so she got a jumpstart and drove home. It's only a short drive though (5-7 minutes) and she turned the car off for the night. Next morning, she goes out to start it and it won't start again. Thinking she didn't let it run long enough to charge the battery, she called AAA for another jump. Before they even got there though, she tried to crank it again and it started right up on its own. This time, she left it to idle in the driveway for a while to make sure she charged the battery. But my (normally intelligent) wife was running on fumes and the car ran out of gas. (I'm a pilot and was out of town for all of this). It must have been long enough to charge the battery though because after she put gas in it, it started right up. And from that point on, the car functioned normally for about a week.
Yesterday morning, she went to start the car and it wouldn't start. (It was cold, about 30 degrees). This time she hadn't left the lights on or anything. She said her remote door unlock worked, but nothing happened when she turned the key. No lights, sounds, nothing. She had to run though, so she left it and took my car. Later that night, about 10 hours after it failed to start, we both went out there to look at it, and she turned the key and it started right up (still cold, about 34 degrees). The eye on the battery, btw, is black. It doesn't show red or green.
If the battery was too low to start the car, how would it gain sufficient charge on its own just sitting out in the cold to start later? My concern is that maybe her depleting the battery the first time or running out of gas may have damaged the battery or electrical system somehow. Is that possible?