So which battery monitoring app do you use?
#1 NONE of them give updates on any consistent basis and 0 of them give them every 30min, what they are hoping that you do which I would say 95% of us do is
open the live tile to make sure it's correct that so we don't actually wait until it updates. If you just let it sit none will update on a regular basis, and all the I've tried (at times) if left on their own will stay the same for up 8 hrs, Try it, don't open it at all and see how (not) often they update, it will surprise you.
I've tried Insider and Battery Pro+ which sort of sponsored by Nokia Poland ( Wunderman Polska) in other words not an official Nokia battery app and I'm current using this one
Battery | Windows Phone Apps+Games Store (United States)
When I leave my phone at my bedside and go to the start screen 7 hr later it isn't updated from the night before but it doesn't seem to use much battery, I guess BECAUSE (even tho' it's running in the background) it doesn't really do much anyway so the drain is minimal. Try one and don't tap the live tile all and see how often it "updates" on it own, if you want the current correct % in the meantime go to system and scroll down to battery, it says % without even opening it.
I don't know why no developer has created an app shortcut to the battery saver, it's correct and it shows what's important and you can turn on or turn off the battery saver. There are shortcuts to many of the other important settings like Wi-Fi, Network, Bluetooth, Messaging, Emails, Location, Airplane that are turned on or off on a regular basis, why not one to the
battery saver, it only makes sense. Who needs one that drains the battery and doesn't update on any regular basis?