I use Phil Endecott "Topo Maps". You download whatever USGS quads you want. It is identical to the USGS quad maps, showing trails etc. At least, every place I have a (paper) map of, appears exactly the same on my iPhone topo.
Tracking with the GPS will eat up your battery power in a hurry, regardless what type GPS, hiking, topo, golf GPS, the map function on your phone, doesn't matter, It's been my experience that using a GPS will use up the battery quick.
Here's what I do. I rarely go into an area that I do not have a map. When backpack hunting out west, I use a map and compass. I will turn on the phone just to confirm my location, then turn it off. This allows me to keep my iPhone power for several days. It's lasted for a four day hunt with power to spare by doing this. But I want to know where I am on a map and not totally depend on an electronic device.
I also carry a Mophie power pack for recharging though as yet, have never needed it.
If I'm on a day hike or hunt, I can pull up the map and only occasionally turn on the GPS to pinpoint my location on the map then turn off the GPS locator while still keeping the map up.
It's the actual GPS tracking that uses so much battery power.
