I need to update our article about using the iPhone for mapping while backpacking
The article is accurate for iPhone 4, but wildly inaccurate for iPhone 5. I could use some help.
SUMMARY
- The ATT iPhone 4 is a terrific backpacking tool when the SIM is locked or removed.
- The ATT iPhone 5, with SIM locked or removed, has egregious battery drain. Certainly this must be a bug that Apple should fix.
- The ATT iPhone 5, with SIM unlocked, in backcountry conditions (no ATT signal, Airplane mode off so that GPS works), is usable for day hikes. But it is not viable for backpacking unless the user remembers to engage airplane mode after each GPS read. With no signal and Airplane=OFF, there is a baseline battery drain of ~1% per hour.
- The Verizon iPhone 4 was not viable for backpacking unless user remembered to engage Airplane mode after each GPS read.
- I have no information about the Verizon iPhone 5.
THE CHALLENGE
Find a SIM state and/or a configuration of iPhone settings that gives minimal background battery drain given these conditions:
- iPhone 5 – ATT (and, for users other than myself, Verizon iPhone 5)
- Airplane mode OFF (which is necessary to use the GPS function)
- Location Services ON
- Phone powered on, but asleep, with no user activity and no apps running
In ATT iPhone 4, 1-2% drain per 24 hours is achieved by either removing or locking the SIM, and it works no matter whether there is ATT signal or not, and works whether the phone is in Airplane mode or not. I’d like to achieve the same baseline drain using an iPhone 5. To be clear, the ATT iPhone 4 is FINE, my backcountry usage patterns give me 5-10 days of usage between charges. The iPhone 5 is not fine, however, and I’m trying to learn everything I can.
I recognize that I incur additional drain when I use Gaia GPS to look at my map or use the camera to take a photo. However, we need to achieve minimal background drain in order to enable backpackers to use the iPhone for multi-day backcountry trips without recharging the phone.
Faraday Cage to block signal:
Create a Faraday Cage. Test that the phone does not have signal by calling yourself to make sure the phone does not ring. In my case, I had to put the phone inside a covered metal cookie tin and put that tin in the microwave. Neither the tin nor the microwave alone successfully blocked signal.
SETTINGS in my test configuration:
I have tried to turn off all features that might drain the battery and which are not needed while in the backcountry:
- iOS 6.1.4 (similar to results I had with 6.1.3)
- Airplane Mode = OFF (while backpacking this must be OFF to make GPS work)
- WIFI = OFF
- Bluetooth = OFF
- Personal Hotspot = OFF
- Notifications = nothing. No sounds, no badges, no alerts, no nothing. (This is messy to undo after a trip, hopefully it won’t be necessary to change any of this assuming that WIFI and Cellular are both OFF.)
- –> Down at bottom of Notifications – Amber Alerts and Emergency Alerts = OFF
- General->About->Advertising->Limit Ad Tracking = ON
- General->About->Diagnostics and Usage = Don’t Send
- General->Usage->Battery Percentage = ON
- General->Siri = OFF
- General->Cellular = OFF
- General->VPN = not configured for anything
- Privacy->Location Services = ON
- Privacy->Location Services->System Services (all the way at bottom of Location Services): Everything OFF except Compass Calibration, which is useful while hiking
- iCloud->Storage&Backup = OFF
- iTunes&App Stores->Automatic Downoads = OFF and Use Cellular Data = OFF
Shut down all apps and power cycle phone.
After a full power cycle and with all apps fully shut down, note time and battery usage. Put the phone in the test environment and check battery usage after some period of time, minimally 60 minutes, ideally 12 or 24 hours.
- Three different SIM states to test: Removed, SIM Locked, SIM Unlocked. (any of the three is a viable solution since user can be educated as to which one to use)
- Two different signal states to test: Strong signal, Faraday Cage. (user has no control, so we need a solution that works in both conditions)
NOTE#1: Once I’ve found an iPhone 5 configuration that is acceptable (<5% per day, ideally 1-2% per day like the iPhone 4), then I can experiment with the list of settings; perhaps some of those I’ve listed don’t matter. And maybe, if I’m really lucky, there’s a setting I missed, and the solution to this problem is as easy as changing one more setting???
NOTE#2: Verizon iPhone4 has no solution to this problem. In the world of iPhone 4’s, only ATT made for a viable backpacking tool. I’d love to see somebody with a Verizon iPhone 5 do the testing necessary to add accurate advice to our article — http://adventurealan.com/iphone4gps.htm
My Results, ATT iPhone 5
SIM Locked. When there is no ATT signal, the SIM is locked, and Airplane mode is OFF, the iPhone 5 battery drain is 10% per hour. Egregious, unbelievable, horrible, terrible. In iPhone-4 locking the SIM was the best solution for backpacking (1-2% drain per day). In iPhone-5 it is completely unusable. This drain is so bad that the SIM Lock feature is unusable even for the average non-hiking user.
SIM Removed. When there is no ATT signal, the SIM is removed, and Airplane mode is OFF, the iPhone-5 battery drain is ~8% per hour. Not quite as bad as the SIM-Locked state, but completely unusable. In iPhone-4, removing the SIM worked as well as locking the SIM.
SIM Unlocked. The drain depends on various factors:
- Airplane Mode = OFF and ATT signal present: ~8% drain per day
- Airplane Mode = OFF and ATT signal absent (this is the normal state for backcountry hiking): ~24% drain per day (compared to 1-2% per day for iPhone 4)
- Airplane Mode = ON and ATT signal present: ~4% drain per day
- Airplane Mode = ON and ATT signal absent: ~4% drain per day
