Android GPS apps are often criticized for using battery life, when the mere fact that they use the GPS guarantees that they will. Battery life is especially important for those using Android GPS apps in an outdoor settings, such as hiking or hunting using Topo maps and GPS waypoints.
Comments in the Android Market will say things "App is battery hog", "I would rate this app higher but it drained the battery a bit".
You can often get the battery to last longer, and still get good use out of the Android GPS. Without any hardware changes, the solution, in oversimplified terms, is to use the GPS less.
The following are measures that will work in conserving battery life with an Android GPS:
- Turn off other radios you won't be using. This includes bluetooth, wifi, and the phone function. You turn off the phone function using Airplane mode. Due to a bug in Motorola devices, you should wait until you have your first fix, then turn on Airplane mode.
- Turn the GPS function off when not in use, then on when you need a location. BackCountry Navigator has a button for this purpose.
By turning the GPS on and off, I found that I was able to complete a three day backpacking trip using only 15% of the battery. The Android GPS still kept me from taking the wrong trail on several occasions. The first fix of the day took a minute or so, but I could turn it on later and find the new location in ten seconds or so.
Some have questioned why BackCountry Navigator has a "Start GPS" and "Stop GPS" button, instead of just using the GPS all the time as some other apps do. Be glad it is there. It is your greatest weapon against battery drain.
The following are things that will not work, at least not completely, in getting more life from a battery when using an Android GPS:
- Turning off the screen with app(s) still using the GPS. Even if the screen is off, GPS updates will continue to consume battery life. The phone won't go completely to sleep in these cases.
- The app registers for less frequent updates. An app can specify that it wants to receive location updates every 5 seconds or every minute. While this sounds promising, it doesn't work. I've found that many devices will *never* get a satellite fix unless you set the updates to one second.
- Changing the update frequency (min distance, time) for tracking. While there are other good reasons for having these adjustments, tracking is a scenario that requires the GPS to be constantly active.
Here are some things that might work:
- A fancy low power mode in the app that would turn the GPS on for long enough to get a solid fix, then off for a user specified period, then on again. It would require that you can get by with a minute or more between fixes. Again, this isn't really changing how much the GPS uses battery – it just changes how much you are using the GPS. A lot more research and experimentation would be needed to see just how much battery this would save.
Keep these things in mind as you spend time with an Android GPS in the outdoors, so you don't have your battery drain before you really need to know your location. And please write to the Android phone manufacturers to encourage them to use less battery in the GPS chip.