I took my first hike today in a long while. My son, Alan, went with me and I tried out the GPS feature built into the iPhone for the first time in any serious way. I bought MotionX-GPS at the iTunes app store and tried it out on the hike. It is a pretty neat feature and works very well with the iPhone.
One disadvantage is the battery use. It was a short hike and I started with the battery at about 75%. By the time we were at the turn-back point 1:15 later the battery was at 25%. I probably could've done much better by turning off the 3G and some other features, but this was still a significant drain on the battery. Undoubtedly much of the drain is due to the app being in contact with either cell phone towers or GPS satellites almost constantly. This produces really cool tracks, but they may not be worth it for longer hikes. If I am going to use this for longer hikes or backpacking, I will have to turn off the phone between stops and only take waypoints.
You can either take just waypoint data, or you can also take a snapshot of the spot using the iPhone's camera. This automatically sets a waypoint at the same time. Once you are done you can email yourself the waypoints and/or the track data. These come in .gpx and .kmz formats, the latter of which imports easily into Google Earth.
A sample kmz file with both the track and the waypoints from today's hike can be found at this link . The file is 1121K in size and includes photos taken with most of the waypoints.
All-in-all the app worked great. As long as I am willing to strictly manage the battery drain I think this is a suitable substitute for a stand-alone handheld GPS. At least for the type and amount of hiking I plan on doing.
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I use MotionX-GPS also and I discovered that if you press the sleep button on top of your phone to turn the screen off, it will continue tracking your location and running the stopwatch in the background! I've observed up to 50% improvement in battery life -- I've used it for 5.5 hrs straight!!!
ReplyDeleteAlso make sure you have Bluetooth and WiFi turned off -- those are bigger power hogs than leaving 3G turned on.
I experienced the same thing with MotionX GPS. It sucks my iPhone battery dry in about 90 minutes... even with dowloadable maps over my cellular network turned off. I can't figure it out, as receiving GPS signals is entirely passive. The GPS device isn't transmitting anything, so I don't understand where the battery usage comes from.
ReplyDeleteI hope they fix this battery drainage problem somehow, as I'd love to be able to use this application more.