I wouldn't necessarily take Apple's word on how much of use you can get out of your iPhone given it's mostly marketing and reproduced in specific lab conditions. Here are some real world numbers from AnandTech's iPhone 5 review. The differences can be quite significant for instance, 4.55 hours on 3G and 8.19 on LTE.
Note that this is presumably for a brand new iPhone 5; if you have one that is more than a year old, it would probably be around 80-90% of it's maximum battery capacity.
Lastly, here are some ideas on maximising your iPhone's battery life:
- Disable Location and Background App Refresh for Facebook
- Disable Background App Refresh for Apps You Don't Care About
- Stop Quitting Your Apps in Multitasking
- Disable Push Email Temporarily (especially if you are using Exchange)
- Disable Push Notifications for Apps That Annoy You
It may also be worth doing the test mentioned at the top of that blog post i.e.
So here's the test: write down your usage and standby time, press the
sleep/wake button (or lock button, as some call it) to put the device
to sleep, and set the device down for five minutes. When you come
back, take note of the change in time. If your device is sleeping
properly, then the Standby time should have increased by five minutes
and your Usage time by <1 minute . If your Usage time rises by more
than one minute, you have a drain problem. Something is keeping your
device from sleeping properly, significantly shortening the time it
will last.
From my own experience, I've noticed that apps that utilise background app refresh in concert with location services tend to be pretty expensive in terms of battery usage. Dropbox and Downcast use these to upload photos and download podcasts in the background respectively - location services appear to be turned on all the time when these Dropbox/Downcast features are turned on. I turned off background app refresh and location services for both of these apps and have noticed quite significant improved battery life.
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.
Best Answer
In iOS 9, Proactive services like Siri Suggestions (on the far left home screen page) will consume power. It has nothing to do with the actual Siri.
If you don't like Siri Suggestions, you can disable it in Settings > General > Spotlight Search.
You might also go into Settings > General > Siri and make sure "Hey Siri" is turned off, especially if you have an iPhone 6s or 6s Plus. Your iPhone "listens" for the words "Hey Siri" but only when connected to power (unless you have an iPhone 6s or 6s Plus, then it's all the time), but doing the two things above and then restarting your device should prevent more usage from accumulating under the "Siri" bucket.