Maximizing Orienteer Battery Life

Over the weekend, I went out on a 7h mission with a teammate. We had a blast! Unfortunately, Matthias's battery died pretty quickly into the run, so we lost the benefits of personal tracking (there were some hard points that would have been more fun with two devices roaming around). Fortunately, my phone lasted the whole time (started at 95%, ended at about 55%), and I realized I should probably write a bit about how to make batteries last long enough for very large runs.

There are generally five things that can greatly affect battery life, only two of which are in the app itself:

"Run Mode" - in the Orienteer app, you can switch between "hyper" (obnoxiously frequent pings), normal, and "battery saver", which adaptively switches between ping times depending on how close you are to a checkpoint. If you're worried about it, use battery saver. If you think you're at a checkpoint and the phone isn't pinging, open up the app, and it'll switch to 1-2sec updates (unfortunately, even in "hyper" mode, the operating system doesn't allow 1-2sec updates while backgrounded in many cases.
Screen usage - the more you look at the Orienteer app, especially the map screen, the more battery you'll use. Print out a map and bring it, and minimize your use of the screen and you'll get more run time.
"Battery saver" mode - on many phones there's a battery saver mode, which limits background tasks and saves a bunch of battery.
Airplane mode - if you have a really long course, especially with spotty service, airplane mode can make your battery last a lot longer.
Actually charge your phone, or bring a battery pack! This one is obvious, but the number of times I've started a course only to realize I forgot to plug the phone in overnight is... a lot.

There's probably more I can do to optimize the app itself, but being aware of the above should clear the way for 8-hour courses without issue!