After letting my car sit for 10 days, it seemed the battery was almost empty. It did crank, but you could count every... sin...gle... comppp...ression. The lights got dim with each try, and the clock lost its time. Finally, there was nothing more than the typical clicking.
Three hours later, I just gave it another try before removing and charging the battery. But surprisingly, the car started immediately, the starter had not even the slightest problem cranking the motor.
Temperatures were not cold, and rose from about 16°C to 20°C during that time. Sure, a warmer battery has more power, and a warmer motor is easier to crank. But yet, I'm wondering because it was not cold, and the temperature rise was low. The battery seemed completely drained, and the started the motor like every day. Oh, and the battery is not that old - maybe 18 months.
Any idea what could explain this?