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iPhone battery life dropped noticeably after getting my first Apple Watch

JulianL

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Original poster
Feb 2, 2010
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London, UK
I'm less than 2 weeks into Apple Watch ownership, an S6, and I'm finding that my battery life on my iPhone 11 Pro Max has deteriorated significantly since I got my AW. I probably get about 60 - 70% of the time between charges now compared to how long I could go before I got my AW. I think I might know why but I'd like to check that my basic assumption is valid and my fix is likely to work.

I think that my iPhone battery life problem is down to me. I always have my iPhone in my pocket when I leave my house but when I'm at home I have a habit of leaving my phone wherever I last used it and I don't use it much when I'm at home which means that at least half of the day, some days more like 80 or 90% of the day, it isn't actually in the same room as me and might well be 10 metres or more away with 2 or more fairly thick walls between me (and hence my Apple Watch) and my iPhone.

I'm guessing that Bluetooth power consumption is related in some way to distance between connected devices and if that is true then my guess would be that I'm causing my iPhone to be using more power than it needs to because I'm forcing it to try and keep connected to my AW at the limits of Bluetooth range. If that's correct (and I hope it is) then the obvious solution would be for me to break my habit of abandoning my iPhone in different rooms of my house and to try to remember to keep it close to me all the time.

Does the above sound valid or is it the case that pairing an Apple Watch inevitably makes a noticeable difference to iPhone battery life?
 

Mr. Awesome

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Feb 24, 2016
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Idaho, USA
I'm less than 2 weeks into Apple Watch ownership, an S6, and I'm finding that my battery life on my iPhone 11 Pro Max has deteriorated significantly since I got my AW. I probably get about 60 - 70% of the time between charges now compared to how long I could go before I got my AW. I think I might know why but I'd like to check that my basic assumption is valid and my fix is likely to work.

I think that my iPhone battery life problem is down to me. I always have my iPhone in my pocket when I leave my house but when I'm at home I have a habit of leaving my phone wherever I last used it and I don't use it much when I'm at home which means that at least half of the day, some days more like 80 or 90% of the day, it isn't actually in the same room as me and might well be 10 metres or more away with 2 or more fairly thick walls between me (and hence my Apple Watch) and my iPhone.

I'm guessing that Bluetooth power consumption is related in some way to distance between connected devices and if that is true then my guess would be that I'm causing my iPhone to be using more power than it needs to because I'm forcing it to try and keep connected to my AW at the limits of Bluetooth range. If that's correct (and I hope it is) then the obvious solution would be for me to break my habit of abandoning my iPhone in different rooms of my house and to try to remember to keep it close to me all the time.

Does the above sound valid or is it the case that pairing an Apple Watch inevitably makes a noticeable difference to iPhone battery life?

Hmmm... my watch didn’t make a huge impact on my phone battery life. To see if Bluetooth is the problem , you can temporarily turn off Bluetooth on your phone, which will force the watch to fetch notifications and data through WiFi, instead of through your phone.
 
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JM

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Nov 23, 2014
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Try experimenting keeping the phone close to you for two days to see how it affects battery life, and report back.

That's the first step to solving this mystery 😁

And I think the apple watch would definitely hurt battery life of the phone since it's connected and sending all the data back and forth. Way back when I had a iphone 5c on iOS 7, I was getting 10hours of on screen time, and when I got an apple watch, the on screen time went down 2-3 hours (ish). I may not be remembering the loss of onscreen time accurately, and it may have been due to updating to iOS 8 or something at some point, but I do remember the apple watch hurt battery life of phone from all the conneciton.
 
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JM

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You could try an alternate experiment of keeping the watch in airplane mode for two days (so it's not connected to phone), and see if the battery life goes back up on the Pro MAx.

If the battery life doesn't go back up, then it's something other than the watch causing battery loss.
 
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JM

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Please report back, though! I'd be really interested to see if we can figure out why you're losing battery. (I always obsess about these things, and a mystery to solve sounds fun, too.)
 
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antbob

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May 12, 2020
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Thats normal. The way Apple Watch is designed to work its basically using your iPhone as external battery pack by oftentimes offloading different tasks it needs doing to it then getting results when its done. If you suspect connectivity problems draining your battery by overusing the radios that would drain both iPhone and Watch and especially Watch is where you gonna notice it the most.
 
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JulianL

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Feb 2, 2010
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Thats normal. The way Apple Watch is designed to work its basically using your iPhone as external battery pack by oftentimes offloading different tasks it needs doing to it then getting results when its done. If you suspect connectivity problems draining your battery by overusing the radios that would drain both iPhone and Watch and especially Watch is where you gonna notice it the most.
Yeah. I confess that did occur to me, in particular that the Watch would also get a bad hit on the battery which being smaller would be more noticeable. I tried to convince myself that because I have no personal frame of reference for what my normal AW battery life would be like since I've never owned one before then maybe I was also getting a hit on my AW battery too but I confess that I'm not very convinced.

More experiments are definitely in order.

Come to think of it I have another theory that might be more plausible. I did tweak my location services setting on my iPhone when I was playing with the Apple Watch hand washing feature where it reminds you to wash your hands as soon as you come back home from being outside. Before that I had my location services pretty tightly locked down on my iPhone to maximise battery life but the AW handwashing set up process told me that I needed to turn on the "Significant Locations" feature which I never had on before. Also Handwashing is the only app where I allow it to always use my location as opposed to just when I use the app (again because the setup told me to). Since the AW has GPS I assumed the location hardware that the handwashing app used would be the one in the watch but even if it is then turning on the "Significant Locations" feature on my iPhone might well account for the drain. I'll have to turn that off again as another experiment.
 
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JulianL

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Feb 2, 2010
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London, UK
You could try an alternate experiment of keeping the watch in airplane mode for two days (so it's not connected to phone), and see if the battery life goes back up on the Pro MAx.

If the battery life doesn't go back up, then it's something other than the watch causing battery loss.
That's a good suggestion although, as someone who has owned an Apple Watch for less than 2 weeks and is still getting a huge kick out of it, asking me to go cold-turkey on the Watch for two days is a pretty big ask right now 😃. I suppose I would still get a reasonable amount of functionality from my watch even in airplane mode, just not anything that needed access to my phone. Come to think of it, it would actually be a good learning experience to discover what does and doesn't work without a phone, which in my case means without a network since I don't have a data plan for my watch and the without-network case is possibly more interesting since loss of network can happen even with a working phone if mobile reception is bad or non-existent. A lot of it's pretty obvious (no phone/network = no messages, no phone calls, no looking up the weather or anything else needing internet access) but would ApplePay still work I wonder. I'm guessing yes since on setup you do need to copy the cards you want to use to be stored locally on the watch but then again maybe something in the payment processing needs my payment client code to talk to something on the network to get a token or for some other reason. I guess I'll have to try it.
 
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wilberforce

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Aug 15, 2020
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I have AW and iPhone 11 pro max also, and no problem with battery or leaving phone in another room.
The AW switches to wifi if it cannot communicate with phone with BT. You can tell by swiping up control center on the AW and see if it has a green phone icon or or your wifi SSID. The AW is quite smart about doing this, and is seamless to the user.
I find my iphone battery is strongly affected if it has poor cell or wifi or gps signal, as it increases antenna power.

Edit: make sure in AW settings you have enabled AW to connect to your wifi
 
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JulianL

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Hmmm... my watch didn’t make a huge t on my phone battery life. To see if Bluetooth is the problem , you can temporarily turn off Bluetooth on your phone, which will force the watch to fetch notifications and data through WiFi, instead of through your phone.
Another good suggestion. Thanks. That's also an interesting learning experience for what works with just network but no phone. I've already discovered just now when I briefly tried what you suggested(*) that some apps don't work presumably because they rely on getting their partner app on my iPhone to do some of the work for them.

(*) Mostly to see if my Apple Watch had inherited the known-network data from my iPhone when I set it up and so would automatically connect to my WiFi - it had, and it did. I've learned yet another thing today.
 
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Mercenary

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Make sure you’re not doing something silly like disabling Bluetooth thinking you are saving battery.

it used Bluetooth low energy to communicate with the watch. If you turn Bluetooth off it will communicate via WiFi and use the phones WiFi which sucks way more battery.
 
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JM

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Nov 23, 2014
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That's a good suggestion although, as someone who has owned an Apple Watch for less than 2 weeks and is still getting a huge kick out of it, asking me to go cold-turkey on the Watch for two days is a pretty big ask right now 😃. I suppose I would still get a reasonable amount of functionality from my watch even in airplane mode, just not anything that needed access to my phone. Come to think of it, it would actually be a good learning experience to discover what does and doesn't work without a phone, which in my case means without a network since I don't have a data plan for my watch and the without-network case is possibly more interesting since loss of network can happen even with a working phone if mobile reception is bad or non-existent. A lot of it's pretty obvious (no phone/network = no messages, no phone calls, no looking up the weather or anything else needing internet access) but would ApplePay still work I wonder. I'm guessing yes since on setup you do need to copy the cards you want to use to be stored locally on the watch but then again maybe something in the payment processing needs my payment client code to talk to something on the network to get a token or for some other reason. I guess I'll have to try it.
Haha yeah I know new tech. I'd be reluctant to stop too. 😆
 
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JulianL

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Sigh. I think I'm a total and utter idiot. In fact I could even attribute a second meaning to what has now become a very well known term and call myself a "Covidiot".

I installed the NHS England exposure notification app three days after getting my Apple Watch and for some reason completely forgot about that (I think because I was so distracted playing with the Apple Watch). If I take that in conjunction with my having enabled for the first time ever the "Significant Locations" toggle in Settings/Privacy/Location Services/System Services on my iPhone which I'm guessing increases the number times my iPhone accesses its GPS hardware in any given day those two taken in combination would seem to me to be more than enough to account for the change in battery life. For the NHS app I also might not have really seen much battery life impact in the first few days because I installed it on the day it was released and I would expect the impact on my iPhone battery life from that app to increase over time since it does local matching and that is at least somewhat computationally intensive with the amount of compute time required probably proportional to the size of the infection database (or perhaps to the size of the regular updates to the infection database if its doing incremental matching). As more people download and start to use the app the number of people reporting themselves positive via the app is also likely to increase (assuming actual number of daily positive test results in the country doesn't start declining significantly) which will increase the number of new Temporary Exposure Keys that the local app has to match against every day or however often it fetches database updates.

Thanks to you though Wilberforce I did accidentally learn another thing about Apple Watch networking...

I have AW and iPhone 11 pro max also, and no problem with battery or leaving phone in another room.
The AW switches to wifi if it cannot communicate with phone with BT. You can tell by swiping up control center on the AW and see if it has a green phone icon or or your wifi SSID. The AW is quite smart about doing this, and is seamless to the user.
I find my iphone battery is strongly affected if it has poor cell or wifi or gps signal, as it increases antenna power.

Edit: make sure in AW settings you have enabled AW to connect to your wifi
I'd already read up about how AW always tries to use its lowest power route to the network, Bluetooth to the phone if it can find it otherwise a known WiFi network and finally the on-phone data plan if enabled. After seeing your post though I could see the blue WiFi icon lit up all the time in my AW control centre but didn't see any green phone icon so I was beginning to get worried. I then realised that I had mistaken the green icon at the very top left of the screen for a battery charge indicator and that it was that bit of the control centre that you were talking about not the buttons themselves. I did then switch off my Bluetooth, see that green phone icon replaced with the blue WiFi icon plus my home WiFi SSID displayed next to it, and then when I enabled Bluetooth again it went back to the green phone icon so that all seems to be working OK.

This really is my day for being an idiot 🙄. I think I need to go and have another cup of coffee to try and rescue the rest of today!
 
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JM

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Sigh. I think I'm a total and utter idiot. In fact I could even attribute a second meaning to what has now become a very well known term and call myself a "Covidiot".

I installed the NHS England exposure notification app three days after getting my Apple Watch and for some reason completely forgot about that (I think because I was so distracted playing with the Apple Watch). If I take that in conjunction with my having enabled for the first time ever the "Significant Locations" toggle in Settings/Privacy/Location Services/System Services on my iPhone which I'm guessing increases the number times my iPhone accesses its GPS hardware in any given day those two taken in combination would seem to me to be more than enough to account for the change in battery life. For the NHS app I also might not have really seen much battery life impact in the first few days because I installed it on the day it was released and I would expect the impact on my iPhone battery life from that app to increase over time since it does local matching and that is at least somewhat computationally intensive with the amount of compute time required probably proportional to the size of the infection database (or perhaps to the size of the regular updates to the infection database if its doing incremental matching). As more people download and start to use the app the number of people reporting themselves positive via the app is also likely to increase (assuming actual number of daily positive test results in the country doesn't start declining significantly) which will increase the number of new Temporary Exposure Keys that the local app has to match against every day or however often it fetches database updates.

Thanks to you though Wilberforce I did accidentally learn another thing about Apple Watch networking...


I'd already read up about how AW always tries to use its lowest power route to the network, Bluetooth to the phone if it can find it otherwise a known WiFi network and finally the on-phone data plan if enabled. After seeing your post though I could see the blue WiFi icon lit up all the time in my AW control centre but didn't see any green phone icon so I was beginning to get worried. I then realised that I had mistaken the green icon at the very top left of the screen for a battery charge indicator and that it was that bit of the control centre that you were talking about not the buttons themselves. I did then switch off my Bluetooth, see that green phone icon replaced with the blue WiFi icon plus my home WiFi SSID displayed next to it, and then when I enabled Bluetooth again it went back to the green phone icon so that all seems to be working OK.

This really is my day for being an idiot 🙄. I think I need to go and have another cup of coffee to try and rescue the rest of today!
Glad you figured it out 😂
 
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