[Acer Iconia A500] Neoprimal:
Lets run some tests, shall we?

I don't think they're shutting off, I think they're crashing/freezing during sleep and not rebooting.

This is speculation by me, and could be different for different people.

Finding the problem:

The test.

Night/Bedtime

This is an overnight/while you sleep test and requires about 2hrs. of your time beforehand. Record your figures if you can and post them for debunking. A couple hours before bed and while you use the tablet during the evening, charge it. After 100% and once it's off the charger please don't use it for anything. We want to simulate the sleep process for about 90m before bed. So if you use the tablet even for a quick web surf, plug it in and getting back to 100%. We're going to allow ~3% for errors anyway but we want to be as close to accurate as possible.

90m before you're ready for bed remove the charger. Don't use the tablet simply set the brightness to auto and take note of your battery level and the time. 60m in take a look at that battery charge again and record the time and charge level. 90m in is the last check and after this whether you go to bed or not please don't wake the tablet. Don't worry if it seems to wake and go back on it's own. That's inconsequential for this test. Just put it somewhere that no one will bother it and resist using it until you wake up. Please :)

Morning/Wake time

Wake it up.

1. Comes on? Record the charge level and time for posterity so we get an idea of idle drain here on the thread. Everyone gets different values. You'll have to run this test at another time as your shutdown/freeze hasn't been reproduced this time.

2. Doesn't come on? Try a power on press. Comes on? Same as 1. Record the charge level and time and post it here.

3. Doesn't come on? Try a power on press. Doesn't come on? Plug it in and power it on. Now do the same as 2. Record the charge level and time and post it here.

I hypothesize a few different scenarios the summary of which is that I don't think they're shutting down, but this is mostly based on the assumption that the batteries are being charged while the unit is frozen. If they do not charge then my entire test would have to be re-designed. I surmise they freeze and don't restart so they either run out of juice or they're actually frozen when you try to power them on and the long press is rebooting the unit, not powering it on. If I am right then we should see that the batteries are drained as if they have been on all night. This is going to be very imprecise, but my idea is that we'll take the charge % of your bedtime check which is a 60m mark check and just times that by the amt. of hours you were sleeping.

So if you were at 95% when you touched the tablet for the last time, this would mean a drain of ~5% give or take ~1% due to your use while checking, per hour. You take that and multiply it by how many hours you've slept and you'd get X x 5 = 40% which leaves the tablet with ~60% battery when you wake up, again give or take 3% for errors, syncing during the night etc.

If you're seeing a somewhat accurate numerical representation of this formula then it means the tab drained all night.

If you're seeing something way off like the tablet still having way more than it should then it means at some point in the night it really did shut down on its own.

People who are actually saying it shut off probably just reboot the tablet without realizing it as it was on the charger when it froze. Since a power off/reboot press of the power button is roughly the same length as a power on press, it's difficult to differentiate sometimes.

Solving the problem:

I have had this happen twice and it was while I left GPS on.

I haven't had an android cell phone yet that hasn't frozen or reboot itself when I left GPS on for extended periods (aka overnight) so the first time this happened I instantly knew to check and I purposely left it on the second time to reproduce and the second time, the tablet ended up rebooting not freezing. If you're not technical the easiest way to know if your tablet reboot during the night is to leave a web page or IM window on the screen or leave music playing.

You may want to skip the above "finding the problem" tests and attempt this "solving the problem" test. As I mentioned, this is all speculation so I'm just trying to get to the bottom of it and I'm sure we can as a grp.

Once you rule out hardware though, then it's a problem. So if it is indeed NOT the GPS then we're at the mercy of Acer and Google because otherwise there'd be just too many factors to track down.