Why do navigation apps drain your battery?

I went to a survival run training camp this last weekend (which was awesome!), but I didn’t know if they had power or not, so I didn’t bring my lightning cable[1]. I used Google’s app to navigate the 1.5 hour drive consisting of mostly long highway stretches (15 miles here, 30 miles there, etc). This navigation drained my battery by approximately 30% one-way, for a total of 60% both ways, leaving me less power for the trip than the transit.

Being an iOS developer, I know a fair amount about location power management, and this stack overflow post is basically correct in its listing of GPS accuracy modes:

  1. GPS – kCLLocationAccuracyBestForNavigation;
  2. GPS – kCLLocationAccuracyBest;
  3. GPS – kCLLocationAccuracyNearestTenMeters;
  4. WiFi (or GPS in rural area) – kCLLocationAccuracyHundredMeters;
  5. Cell Tower – kCLLocationAccuracyKilometer;
  6. Cell Tower – kCLLocationAccuracyThreeKilometers;

Obviously, if you’re driving in a city and blocks matter, you need high accuracy. I have no problems with running the GPS all the time in a city. But if I’ve just been told to drive 30 miles – just over 48 kilometers. Turn the GPS off. Kilometer accuracy is more than good enough to make sure I’m not wildly off track and to know when I’m getting close, and using the GPS takes WAAAY more power than using cell towers (especially since the phone has to talk to the cell towers anyway). Seriously, leave the GPS off until I’m near the next turn![2]

[1]In retrospect, bad idea. Always take your charger just in case.
[2]The only reason I can see to use GPS on long highway stretches is if the phone is actively running the app because someone is staring at the little GPS dot the whole time. If the user wants to stare at their dot for 30 miles and use the energy to do so, fine. But the app knows when it’s been backgrounded; It knows when nothing interesting will happen for miles and miles. Please: Leave the GPS off until I’m close.

About Bion

I'm a software developer at Modo Payments, a mobile payment provider. When I'm not hacking away the office, you I'm usually at home hacking on something else. Or practicing Aikido. Anyway, I just post things here that Google couldn't help me with, so maybe it'll help you in the future. Since you're reading this, I guess it worked :)
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