I was under the impression that Power Reserve mode was automatic when you run low on power or if you decide to turn it on. But I was in a different post that says that all you see is the message that pops up when you have 10% left and you're supposed to turn it on yourself. Can someone also confirm if there is an auto ON percentage point for the Power Reserve Mode or if you're just supposed to hit the PRM button when you hit 10% and the notification pops up? Another question I have; is the 72 hour battery life in Power Reserve Mode from the remaining 10% when it asks you to turn it on? Has anyone actually tested out the 72 hour PRM battery life yet?