[Verizon Samsung Galaxy Note II] mikeyxda:
No, the stats showed nothing keeping it awake. We determined that was the amount of current needed to keep the phone at idle with the radios off, no extra apps running, and the screen off. Now, I'll admit we didn't do a clean install and then boot on the first boot (after a clean install) with airplane mode selected so that the phone would be completely empty! We had all the basic apps installed, the play store activated, calendar and contacts with what we normally used, etc. Just the calendar alone caused entries in logcat even when there were no active reminders on the calendar for that day. Clocks, widgets, and other things were being updated in the background, and so on. As I said, look at a logcat when in airplane mode and you'll see what is going on. There are dozens of entries every hour and for each entry in that log, it means at least one CPU was awakened and turned on: else you'd have no log entries.

The problem I have with this is that the 1% per day figure gets you to 100 days, a little over 3 months. In general, I've seen a week to 10 days but that was with at least a minute or two screen on time. So... I could get to 2 weeks on a typical setup. Now, if I scoured the logcat to determine what is going on and really streamline the phone, I could probably find a way to get 30 days before the battery died if I put it in airplane mode, deactivated a lot of stuff, and never turned the screen on. So I don't have so much of a problem with 30 days even though it's out of the range of the typical setup.

1% per day though (3+ months) or this "several months" figure: never happen. The reason is just simple physics. In 3 months, a lithium ion battery will lose 30% just from internal resistance. So let's use the 3 month figure (the minimum at which you can claim "several" months life). The phone has a 3100 mAH battery which means it can deliver 3100 milliamps for one hour and then it's dead. Or 310 milliamps for 10 hours. Or 31 milliamps for 100 hours. And so on.

In 3 months, the battery will be down to 70% if you fully charge it, take it out of the phone, and just leave it on a table. That means you have 70% of 3100 mAH left to run the phone. So the phone has 2170 mAH of capacity (70%) to get you through 3 months.

- 3 months = 90 days

- 90 days = 2160 hours

- Capacity available during the 90 days = 2170 milliamp hours

- 2170 milliamp hours/2160 hours = 1.0 milliamp continuous

So if the phone draws any more than 1 milliamp, it will die before 90 days. Try to understand how little current 1 mA is. It takes about 20 mA to operate a single LED (like the one that blinks for a notification). So the amount of power you are allowed to use in order to get to 90 days is about one twentieth the amount of power that it takes to light a notification LED. Notification LED's blink so they are only on maybe 1/5 of the time so they may only draw 4 mA in blinking state but that's already 4x what you are allowed. And the simple counter circuit that causes the LED to blink draws a continuous 5+ mA on top of that. On top of that, you have to supply enough current to keep memory alive, CPU's in the idle state, timers to cause the phone to wake every so often to do things like update the clock, etc.

It's not that I'm basing this all on a blinking LED. It's the fact that 1 mA is at least 5x less than the phone needs just to keep it in a hibernate state. If a simple timer to cause an LED to blink draws about 5 mA, you can imagine what it takes to keep RAM powered up so that all the 1's and 0's aren't lost, run system timers so the phone can check for things like time, calendar events, and other "local" things that don't require an internet/data connection. Even if all you needed was the 5 mA to run a system timer, at 5 mA, your phone will be completely dead in 26 days, and that's not even factoring in battery self-drain. That's just running the counter that does nothing but wake the phone when it needs to do things like check the battery or the calendar. How do you think your phone knew to start blinking at 10% when you thought it was off? There's circuitry in there that monitors things like that and I guarantee you the circuitry just required to hibernate uses a lot more than 5 mA. Is it all on, all the time? No, but you can bet that at least one timer is continuously running because the phone has to know when to perform certain maintenance tasks, so 5 mA should be a good minimum figure.

Also consider this. You thought you turned your phone off and discovered it blinking 31 days later. How do you know it was on that whole time? The phone could have had some mechanism to turn it back on after some period of inactivity or something along those lines could have caused it to turn on after being off for say 20 days. Stranger things have happened.

Mike