I put my phone into Airplane mode to charge it faster. This morning, I wanted to check the weather to see if I needed a jacket or not, so I disabled Airplane mode, turned on all the location settings, and pressed the refresh button on the weather app. By the way, the weather app still didn't update, but my battery drained over 50% in less than 2 minutes. I put it on the charger right after and it was back at 70 after a half hour. Has kept up the battery since, fluctuating between 79% and 80%
Galaxy S3 SGH-I747 I think.
AT&T carrier and 4.1.2 firmware, rooted kernel.
No the phone didn't heat up at all. The screen being on is normal, being as this drop happened instantly within 2 minutes.