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I use my iPhone 4 as a GPS device when I go tramping, but since the phone is constantly searching for signal in remote locations it drains through the battery extremely quickly.

The simple solution is to remove the sim card, although I've lost one microsim this way, and it's not an ideal solution.

I'm looking for a method to disable the phone/transmitting functions, while still being able to use GPS. Does anyone know of any apps (I guess from the Cydia store - I doubt Apple would allow this) or method to achieve this?

Edit: Just to be clear, what I'm meaning is that all transmitting functions on the iPhone are turned off - the only thing that should still be functioning is the GPS.

The 'phone' toggle in SBSettings doesn't work because it disables most things including GPS, and just leaves wifi enabled.

Update: Just to be clear, the same result I'm looking for can be achieved by removing the microsim, it's just that it feels like there should be an easier way to accomplish this without removing the sim.

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Just some clarification, what app do you use when using your iPhone as a GPS only? –  Jeshii Feb 1 '11 at 18:02
    
Normally GPS Motion X - I like it because it let's me pause, close the app and open it up again - I close the app and put in airplane mode overnight when I go tramping. I'd use Runkeeper Pro in the past as well, but now I just upload the GPS logs from GPS Motion X when I get home again. –  Ciaocibai Feb 1 '11 at 20:11

8 Answers 8

If jailbroken, SBSettings allows one to turn off everything: Data, Wifi, Bluetooth, 3G, Edge, Phone, SSH, etc. but leave GPS enabled.

If not jailbroken, Settings > General > Network lets you turn off WiFi, 3G, BlueTooth, and Data, which leaves GPS, Edge, and Phone. Turn brightness all the way down. This ought to extend battery life quite a bit.

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Doesn't this just disable data, but not the phone itself? It seems I can make phone calls with everything disabled in this way - which means the phone would still be searching for signal and using battery. Oh, and currently on a tethered jailbreak - might see about changing that though. –  Ciaocibai Jan 25 '11 at 0:09
    
Yes, as I said, Edge remains, unless you turn it off with SBSettings. –  user588 Jan 25 '11 at 0:15
    
Even with edge off in SBSettings I can make phone calls. I might be confused but I thought Edge is just for transmitting data, not for making phone calls - even with all of these things disabled, I can still make phone calls. What I'm hoping for is a solution that means everything is disabled except GPS, and that the phone won't be searching for a network. –  Ciaocibai Jan 25 '11 at 1:14
    
You are right. SBSettings is still the answer. I updated my answer above. Under SBSettings > More > Set Toggle, you can add a Phone toggle and turn it on/off. –  user588 Jan 25 '11 at 2:14
    
On my iPhone it seems the phone toggle disables everything, including GPS - I read a comment from BigBoss at Macrumors saying that the phone toggle is in fact the same as airplane mode, and everything (but wifi) is disabled. Can you tell me if you can you can use GPS with that phone toggle switched to off? –  Ciaocibai Jan 25 '11 at 4:16

I'd thought I'd share - the best way to do this without needing a paper clip and peeling off your case is to use the SIM PIN function. Turn it on (Settings->Phone-> SIM PIN) and reboot the phone. When it asks to unlock the SIM, just hit cancel. This will have the same effect as removing the SIM

Of course do to this you'll need the SIM PIN. For AT&T the default is 1111. You should be able to get your SIM PIN from your carrier.

Not sure if this works with non-SIM iPhones, i.e Verizon.

http://adventurealan.com/iphone4gps.htm

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Your primary concern is battery life. The number one battery drainer is when the screen brightness is set higher than necessary. Also make sure Auto-Brightness is turned on. This will somewhat automate the process for you, but it unfortunately isn't as effective as manually adjusting the brightness as needed (while still keeping the Auto-Brightness setting turned on).

The next two things that drain a lot of battery (excluding GPS) is the Bluetooth and Wi-Fi radios. Turn them off as often as possible.

Next I have found that GPS still functions when you turn off 3G and Cellular Data. Those certainly drain a bit of battery. The phone is, in fact, still functional after turning these off, but you should still get longer battery life by sticking with EDGE. And to answer your comment earlier, EDGE is used for for both voice and data. Perhaps the GPS radio is integrated into the cellular radio; possibly explaining the lack of independence here. The reason I suspect this is because the cheaper Wi-Fi iPad lacks GPS functionality.

Perhaps even a reboot is a good idea to stop any multitasking apps from running in the background or even staying in memory. Also, I'm not sure if it's necessary to turn off Notifications if you already turned off Cellular Data, but it may help too. Especially if you left Cellular Data on, then you wanna at least turn off Notifications.

And here's a thought, perhaps turning off MMS Messaging could also help...?

Alternative options could be to simply turn off your phone completely between uses or to switch back and forth between Airplane Mode as needed. And finally perhaps a phone call to Apple may clear things up.

P.S. I also just thought of one more idea, there are ways to disable multitasking with various Cydia apps once jailbroken. I'd imagine this would drain less battery if you turned that off as well.

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Doesn't 3G use more battery than Wi-Fi? –  Senseful Feb 7 '11 at 21:40
    
Perhaps, but 3G is not something most people would wanna turn off unless you're in a poor coverage area or aiming for maximum battery life. –  Randy6T9 Feb 9 '11 at 9:46

Yet to test but found this in another thread

In IOS 5.0 (9a334), on my Apple Iphone 4, you can now go to "Settings" - "General" - "Network" and there:

  1. turn off "Enable 3G"
  2. turn off "Cellular Data"
  3. turn off "Wi-Fi"
  4. turn off "Data Roaming"

Then go back to top menu under "Settings" and choose "Location Services" then at the very bottom choose "System Services" then:

  1. turn off "Cell Network Search"
  2. turn off "Location-Based Iads"
  3. turn off "Traffic"

It seems to me then that you will be left with GPS and Compass Calibration as items in effect. It is really weird there is no single toggle for "Enable GPS".

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Thanks for your answer, but doesn't seem to work - my phone still connects to the phone network - this only switches data off. –  Ciaocibai Dec 22 '11 at 7:52

I saw this on the backpackinglight.com forum:

"The second option is set up a sim PIN. When you restart the phone, you can choose not to enter the pin. This turns off the phone and allows you to use the gps and prolong battery life. I'm doing a test right now with MotionX. I've been running the track recorder now for almost 15 hrs, and the battery is still at 89%."

They also mention that 3 incorrect pin attempts locks the sim card so be careful if you try this.

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Yeah, this is pretty much the same effect I get with removing the SIM card - works a treat, but micro sims are very easy to lose! –  Ciaocibai Dec 30 '11 at 22:18

I put the iPhone into Airplane mode when I don't need GPS. I turn Airplane mode off when I want GPS. Airplane mode is quite quickly accessible via the Settings app.

I usually take a photo every now and then to track my locations throughout a tramping track (that's the only case I use GPS for while tramping). Since GPS needs some time to connect and get the location anyway, I don't find it inconvenient to fiddle with the Settings app for 2 seconds upfront.

I recently went on a 4-day hike and returned with 75% battery life on my 3GS using this technique. This time, I only took <= 10 or so photos with GPS turned on, though. But as you can see, there should be room for quite some more GPS requests.

Of course, turning off Airplane mode enables every wireless technology on your phone. But I don't think that's too bad. If you turn off 'Cellular Data' and 'WiFi' in the settings, too, before starting a track, the iPhone does not attempt to find a 3G, Edge or Wifi network while in remote areas. Hence you save some more battery power.

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I've done this as well, but I like to record GPS logs of my entire tramps since I do most of my tramping off track and like to be able to look at the entire logs of my travel on my return. I love seeing all that data about distance, elevation changes and such as well. –  Ciaocibai Jan 24 '11 at 23:39
    
Fair enough. Then my 'solution' won't work, of course. However, in my experience, using GPS on the iPhone demands lots of battery life. I doubt one can use the iPhone + GPS constantly longer than a few hours. Even when turning off all other network requests. But I am only talking about my 3GS. Maybe an iPhone 4 does better, I don't know. –  Daniel Pietzsch Jan 24 '11 at 23:46
    
It has lasted pretty well for me - even when doing full days geocaching it still keeps up, and that's while finding information over 3G as well. When tramping I usually carry both a backup battery and a solar battery charger, but honestly, when my phone is constantly searching for signal, it just chews through the battery. It drains flat in half a day or so. –  Ciaocibai Jan 24 '11 at 23:49

Since, when in airplane mode you can only use wifi, try getting MYWI from cydia and turn on wifi tethering which will then display your 3g/edge as a wifi network, allowing it to work even when in airplane mode.

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Although im not sure how much battery MYWI uses. –  eliben Jan 31 '11 at 22:42
    
I have MYWI, but I'm not sure how this is going to help me use GPS only?... –  Ciaocibai Jan 31 '11 at 22:58
    
in order to use gps you need edge or 3g on. airplane mode turns everything off except for wifi. mywi lets you use your 3g/edge as a wifi connection, allowing you to use it even when in airplane mode. I have tried this with my phone and it seems to work. –  eliben Jan 31 '11 at 23:13
    
I can use GPS without the sim card in my phone, so I'm fairly sure I don't need 3G or edge to use wifi. Turning on MyWI would also help burn through the battery, so not quite the solution I'm after. Thanks anyway. –  Ciaocibai Jan 31 '11 at 23:20

As far as I can tell, this isn't possible anymore. It used to be that SBSettings had a "Phone" toggle that allowed you to turn off the phone chip so to speak. Apparently there were some bugs and no one ever bothered to fix them so they just deleted it :(

Removing the sim card is the only way I know of since iOS 4.3 or so when the above mentioned bug was introduced.

FYI, the SIM PIN "hiking mode" hack messes with things quite a bit on jailbroken phones :(

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Can you explain how the SIM PIN "hiking mode" hack messes with things on jailbroken phones? I planned on using this 'hiking mode' for an upcoming trip and would like to know what the problems are. –  user26620 Aug 2 '12 at 18:44

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