iPhone battery life.

Factual Questions
1

I’m trying to figure out if there is something wrong with my new iphone 4S.

I’m using it with Strava, a cycle computer app that uses the GPS to calculate distance travelled and speed. Unfortunately the battery is only lasting long enough to do a 120 km ride, so about 4 to 4.5 hours. I’m turning everything off that isn’t necessary such as wifi and bluetooth and the only app running is Strava, everything else is closed. I’ve tried turning 3G and cellular data off as well but it makes no difference.

To start with I thought the poor battery life was just a limitation of using a smart phone for a cycle computer instead of a dedicated unit like a Garmin and that I’d have to just get used to it but my girlfriend’s iphone doesn’t have a battery problem running Strava.

As an example we both rode 120km on Sunday. We both had iphones running Strava and both phones had 100% charge. The only difference is that hers is an old iPhone 4 while mine is a 4S, also her network provider has better cellphone coverage than mine does. After riding 60km we took a break and my phone was down to 55% while hers was still in the 90s. I had to recharge my phone to ensure it’d last the distance while she could comfortably finish the ride with hers and have it available for phone calls for the rest of the day. Most rides I do I don’t have the luxury of recharging my phone halfway through.

With the battery life I’m getting it seems to just cope with 120km as long as it starts with a full charge, but I’m planning on doing rides up to 200km over the rest of the year and although I’ll probably end up getting a dedicated cycling GPS in the future I’d rather not be forced into it.

Some things I’ve tried. I’ve installed the latest iOS 5 update, I’ve deleted and reinstalled Strava, and I’ve tried minimising other services as described above. The only thing I haven’t tried yet is using it in airplane mode. I’ve seen photographic evidence that the phone’s GPS is still available in airplane mode but I’ve never had any luck getting it to work.

I’m thinking I need to return it to Apple but I’m not sure they’ll accept that the phone is faulty, I’m thinking they’ll say “GPS apps suck battery” and won’t accept my comparison with the other iPhone.

So, any ideas on whether this is normal? Is the difference between my phone and my girlfriend’s because mine is a 4S? Could it be because we use different service providers and my provider has a smaller coverage area and so the phone is spending more time searching for cell towers? Has anyone had any luck using an iPhone GPS in airplane mode?

Edit: Now I see from the Apple website that airplane mode disables the GPS. I have definitely seen a screen shot of an iPad in airplane mode with a GPS working but it may have been an external GPS.

2

I have an iPhone 3GS and also had battery problems with it. I think it had something to do with recharging too frequently and not letting the battery fully discharge on occasion. At any rate, if you have steady hands and are handy with a screwdriver, and don’t mind voiding your phone’s warranty, you CAN buy a replacement battery on Amazon and replace it yourself, but this is not an adventure for the timid of heart.

If you’re not up to that, you can take it to your local Apple store, where they will replace the battery in exchange for an arm and a leg.

3

This could definitely be a factor. My non-iphone cellphone can last for several days at home where I get great reception whereas at my former office where the connection was intermittent it would sometimes crap out in 8 hours.

4

Well if it’s faulty they should replace it under warranty, I’m just not sure if I can make a case for it being faulty.

I’ve connected an external GPS to it and am running a dummy ride on the Strava app in airplane mode to see if that improves things at all.

5

Have you tried calling your local Apple Store to see if they’d replace the battery for you? Sounds like a defective unit - you’re well within your warranty period. Apple is extremely good about replacements/repairs during warranty, especially if you can tell them about your girlfriend’s experience.

6

Unfortunately we don’t have an Apple store in town, just Apple authorised service providers. I’ll have to go through their online service thing and see where that gets me.

7

Yes, this is the most likely cause of the disparate battery performance between your iPhone and your GF’s. As it seems you’re aware of, if you’re not getting a solid signal, your phone will expend more power trying to do all the reconnections to find a suitable signal. I’m not an iPerson, so I can’t lend any assistance about how airplane-mode works re: the GPS, but it should definitely turn off both your voice and data transmissions. (Make sure your wifi is off also, because at least with Androids, it is possible to turn on wifi in Airplane Mode.)

Also, if your GF’s carrier is AT&T and yours is not, since AT&T uses a GSM cell network, and any other iPhone carrier uses CDMA, the battery life of the GSM AT&T phone would be superior to that of the CDMA phone if the cellphone radios of both are on, even if they are both getting a perfectly stable and solid signal. From what I’ve looked into for other non iPhones, GSM transmissions inherently require less power than CDMA.

I’m pretty sure this is false. Lithium batteries do not suffer from memory, and it is actually better to charge them more frequently. And although they have protection circuits that shouldn’t allow them to over-discharge, fully discharging them (as much as the protection circuit will allow) is not beneficial, and could in some cases be detrimental. (If you fully discharge it, then don’t recharge it promptly, it is conceivable that the charge could drop below the “safe” threshold.)

So charge your phone early and often, it is happiest when fully charged/charging, no matter if you’re only slightly topping it off.

But what *will *kill a battery early is excessive heat. So, if you’re phone is charging (which generates heat) and you’re using it at the same time, you might want to be conscious of how hot it’s getting. CPU intensive functions will generate considerable heat, AND radio transmission (voice, data, wifi) intensive functions will ALSO generate considerable heat. So, if your phone is charging and you’re flogging away using a lot of those functions simultaneously, your phone can get pretty hot, and making a regular habit of this probably will lessen your battery’s life expectancy.

P.S. I just know someone will point to some manufacturer’s instructions somewhere about recommending fully discharging the battery and then fully charging it. That’s pretty much hooey.

For more info, Battery University is a very good site.

8

We are in Australia. Her’s is Telstra and mine is Optus, they both use UMTS for their 3G networks according to their respective wikipedia pages.

9

Maybe get a battery pack for it? They fit on like a case, with an extra battery inside and are pretty cheap.

10

Ahh, okay. Both are GSM based, then. Disregard the talk about CDMA networks, which is still a big holdover in the U.S., but much less so in the rest of the world.

11

Can you swap the SIMs to test the network theory? (Might not be possible if the phone is locked to Telstra)

12

Actually, since he’s trying to turn off voice and data anyway, maybe temporarily removing the SIM would be a more “nuclear” option way of doing that. I don’t know from iPhones, but the GPS should still work, I think.

13

Yeah I can try that. I’m not sure if the phones are locked or not. I actually have two other brand new iPhone 4Ss here but they’re supposed to be going back to Telstra sometime and I’m loath to muck around with them*.

Taking the sim out is ok to test whether it is a network issue or not, but long term I will need to have a fully functional phone while I’m riding as I’m often on-call for work.

Doing a bit of research on the internet it looks like 4 to 4.5 hours is not unusual for an iPhone 4S running Strava. I’m not sure why my girlfriend’s phone is doing so much better. The battery pack option is a good one. There are also other cycling apps that are easier on the battery and that can still upload their data to the Strava website.

*I tried to upgrade my previous phone to an iPhone with Telstra a while back. Telstra sent me a phone and then told me I’d failed their credit check. I rang them and they overrode the credit check problem and sent me another phone. I assumed the first phone had been cancelled but they both turned up in the mail. When I tried to activate one of them I found that the credit check problem hadn’t really been fixed and I was told I would have to send them back. This is why I’m now with Optus, who had no problem approving an iPhone for me, and why I have 3 iPhone 4Ss.

14

Perhaps. My understanding of the ‘Assisted GPS’ used in the iPhone is that it first gets a rough location from a cell tower and can then get the satellite info faster. With no cell tower, it takes longer with just satellites - with the GPS radios using much more power.

15

Turn on airplane mode, then turn on location services. You’ll get GPS but none of the other radios. You can then also turn on bluetooth/wifi or whatever else you need.

16

The iPhone 4S has had many battery complains and several updates to try to address this. The 4 does not seem to have this issue.

But I’m in a bit of a opposite situation, my 4 seems to be going down faster then a friend’s 4S. I brought it to the App store Genius bar today for exactly this thing. What they did was run a diagnostic which states that the battery is in ‘good condition’ then go on to tell me to turn off things like push and location apps and to restart the phone more often.

So if you are going to bring it in I suggest you place it in a power conserving mode before hand or you just get a lesson of things you already knew.

When I use it in my car, being charged, using Garmin GPS app + Pandora streaming the phone barely charges and gets a bit hot.

17

I’ll try that.

Update: I’ve reset the phone to factory settings then restored from my backup and am running a dummy ride with the Strava app. It has been running for 50 minutes and is only down to 91% which is significantly better than it had been doing previously. I’ll be happy if I can just get it to comfortably last through the 120 km ride I’m doing in a couple of weeks.

18

Your girlfriend’s ability to use a GPS tracking app on a long bike ride surprises me. I tried to do this a couple times with my old 3g, and had an experience similar, or worse than, yours. Taking the phone with me but not running the mapping app didn’t cause any problem, so it was almost certainly the GPS, and not looking for a network signal, that was killing my battery life. I gave up tracking my distance and path with my iPhone afterwards, and haven’t tried with my 4S. This thread has inspired me to give it a go for my next run/bike ride…

19

Sounds about right. If I don’t charge it simultaneously, my 4S won’t last the length of a 3 hour journey in the car while using a GPS app.

I guess GPS is very battery intensive.

20

The best ways to save battery life are:

  1. Turn your brightness down or use auto brightness
  2. Clear your multitasker every once in a while. Apps like Safari can kill you battery
  3. Lock your phone when listening to music you don’t need to look at
  4. Go into Settings>Location Services, and turn off the unneeded
  5. Go into Settings>Location Services>System Services and do the same
  6. Use wifi whenever you can
  7. Carry around a little charger for when you may need it. Car chargers are reccomended.