In a word, no!
The Squirrel Street Receipt and Mileage Tracker uses geofencing technology, which is very advanced and adaptive. The app will not constantly update your location when your phone is not plugged in.
We've tested this on our own app extensively, and with the app running all day our phones stayed at over 90% battery when we didn't use them excessively throughout the day. If you do encounter a problem, contact out support team and we'll be happy to investigate!
You can learn more about geo-fencing here.