It should be possible to perform a reset of the phone by holding the 'home' and 'power' buttons for ten seconds. That should cause the phone to reboot.
If you can't do this (e.g. broken power button), then I don't see why removing the battery would not cause the phone to be shut down.
I don't see why it would cause any lasting damage, at any rate.
I assume most (if not all) the other devices you refer to were various Android models? If so, how long has it been since you've used a device with a very recent version of Android?
The reason I ask is that Apple's iOS has always been more efficient in its battery management. This is why Apple gets away with using batteries of lower mAh ratings. And it's the reason why Google launched Project Volta - because they needed to make Android more efficient at its core.
In a nutshell, Project Volta resulted in improved efficiency starting with Android 5.0 Lollipop. It achieved this through a series of optimisations (e.g. a new battery saver mode, job scheduling APIs which restricted certain tasks to only activate over Wi-Fi, and performing tasks in batches to minimise the overall time that internal radios were active.
Of course, since that time Apple has also made improvements in how iOS manages power consumption.
However, in terms of answering your question Are these measures true, correct and verifiable? when referring to an iPad still displaying 100% after being idle with Wi-Fi activated all night, the only way for you to know that in your exact circumstances is to do some testing, keeping in mind you need to ensure:
- that you have the exact same apps running during these tests
- all apps (and iOS itself) must be the same version
- the start and end times (and therefore also duration) are identical
- the ambient temperature at the time was identical (in other words, you'd have to do this in the same air-conditioned environment set at the same temperature)
In a nutshell what you would do is something like the following:
- Fully charge the iPad and disconnect it from AC power at 10pm
- At 8am play a movie at full volume and full brightness
- At conclusion of the movie, take note of the battery percentage
- Play the movie again (still at full volume and brightness)
- At conclusion of the movie, take note of the battery percentage again
- Play the movie yet again (still at full volume and brightness)
- At conclusion of the movie, take note of the battery percentage again (assuming you've still got a charge)
Now fully charge the iPad and leave it connected to AC power until 8am the next day, at which point you disconnect from power and perform the same test (i.e. same room, same movie, same volume, same brightness, etc).
Compare the differences in your battery percentage and determine how accurate that 100% reading is.
I suspect that in reality an iPad will use some battery power overnight with the screen dimmed off and WiFi connected, but that the usage will be quite negligible.
Only you can decide, based on your test results, how true, correct and verifiable the measures (i.e. battery charge indicator) are.
Best Answer
Once you have some measurements and data, you can change which apps get notifications, which apps are allowed to run in the background and which apps do background refresh.
You can use the Apple Watch app to deinstall any apps you need to test their power usage and also look at the power usage on the Apple Watch.
People that have honed their iOS power needs over the last 6+ years now have to consider a totally other use case. Now iOS can act as the server backing the Apple Watch as it offloads all of the third party app workload to the iPhone.
Basically, you measure the usage on both devices. Try some changes to minimize the highest users, and then repeat to balance functionality and energy use.
Before watch, my iPhone 6 would end the day with 50 to 30% charge always and when it didn't I knew exactly why I was burning power at a faster rate and planned a charge to compensate.
It's taken a week to sort through Apple Watch and iPhone and I'm actually at better energy use now since I've stopped using the iPhone for some things and have rejected most Apple Watch apps as slow remotes for the iPhone. My glances are down to 6 items I need and 2 for fun. My Apple watch also is making it all day with plenty of power to spare unless I exercise with it for 3 hours a day. That's the only time I've had to do a mid day charge on the watch.