Calendar uses 90% of battery and iPhone is empty over night

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Level 2

164 points

Calendar uses 90% of battery and iPhone is empty over night

I and sure since when, maybe since the update to 10.1.1, but since a few days my iPhone 6 loses power very quickly. When I start with 100% in the afternoon, power is empty the next morning with no interaction. When checking battery use, the info is that Calendar is using 89 or 90% of the power, although I am not using the app very intensively.

I have tried a reset (switch off and restart), but this does not help.

Any hint??

iPhone 6, iOS 10.0.2, 64 GB

Posted on Nov 15, 2016 8:08 AM

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Answer 1

bwadma Author

Level 2

164 points

Nov 20, 2016 1:25 PM in response to kb1951

Any explanation why that should make a difference? Obviously, charging over night will provide power, but it does not solve the sync problem (and the heavy power consumption by Calendar which is also a problem during daytime). Usually, I charge my iPhone only in the car when it is used as a navi. Or while syncing to iTunes via USB.

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Answer 2

KiltedTim

Level 10

225,588 points

Nov 17, 2016 2:03 AM in response to bwadma

If you have an Exchange account set up on the device, it's likely a calendar item that is "stuck" trying to synchronize. Turn off the calendar sync temporarily and see if that solves the problem. If it does, you may need to remove and re-add the Exchange account to the device. If the problem returns, contact your IT department. The problem may lie with your account on the server.

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Answer 3

bwadma Author

Level 2

164 points

Nov 21, 2016 12:11 AM in response to ChrisJ4203

Hi Chris, many thanks for the hints!

- I use an AppleScript to count my Calendar entries in my main iCloud account. It is currently 15,500 entries since Jan 2011. Older events have been moved into a secondary account that is NOT synced to the iPhone but used on my three Macs. (I do this since a few years after I did hit the 25,000 entries limit that Apple had set at that time. I just checked Limits for iCloud Contacts, Calendars, Reminders, and Bookmarks - Apple Support and found that the limit has been lifted to 50,000.)

- The 15,500 events are split over 10 individual Calendars. These are shared in part with my co-workers and with family members. In addition, there are a few imported Calendars that are shared with the family, but these are imported from their iCloud accounts and not exported from mine.

- Since the "battery drain" problem is quite new, I guess that it must be a relatively recent entry that causes the trouble. This assumption is confirmed by the test that Tim suggested: batterie drain did happen over the last night after again deleting all Calendar data from the iPhone and allowing sync only for the last 2 weeks.

- I am using ONLY Apple software & servers for sync. No Outlook or other "external" stuff.

- Isolating the (sub-) Calendar that causes the trouble might really be the next step ... but maybe I try calling AppleSupport before I start this adventure.

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Answer 4

bwadma Author

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164 points

Nov 15, 2016 8:16 AM in response to KiltedTim

Many thanks for the hint!

I have only one account that syncs, but it is a lange iCloud account with 15.000 Calendar items and sync with several family members that share their Calendars.

I will give it a try anyway.

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Answer 5

ChrisJ4203

Level 10

236,297 points

Nov 16, 2016 11:58 AM in response to bwadma

Another thing you might like to look at is to connect the phone to power overnight. That way the device would remain connected to your wi-fi and would be fully charged when you wake up in the morning. Wi-fi, by default, turns off after a short period of time when the device is not connected to power. Power also facilitates your backup to iCloud.

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Answer 6

bwadma Author

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164 points

Nov 17, 2016 2:02 AM in response to ChrisJ4203

Hi Chris, thanks again!

Meanwhile I am sure that your first suggestion was hitting there correct target. I disabled Calendar Sync in the iCloud preferences, and after one day power consumption (averaged over 24 hrs) of the Calendar app was back to a few percent. After re-enableling Calendar Sync for the iCloud, a data merge was done, and sync seems to work OK. However, power consumption of Calendar went up to 89%. This is what I see at the moment.

I am currently deleting all synced Calendar data from the iPhone (option "remove" after disabling Calendar sync). I will do a reboot after that, and then newly download my calendar data. Hopefully, this will fix the "stuck" calendar item. I will see that tomorrow ...

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Answer 7

bwadma Author

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164 points

Nov 20, 2016 4:18 AM in response to bwadma

Update: also replacing the Calendar data with a fresh copy from the iCloud server does not fix the problem. After re-enableling syncing the Calendar data in the iCloud account settings, power consumption went up again.

I tried this twice, once with all my Calendar items (they were on my iPhone since years and I never had such a problem), and once with syncing only the last 6 months. No difference.

(I also noted that power consumption as such is lower when the iPhone is on a WLAN. But I need quite often to rely on LTE, and then power consumption over night really ends up with a completely empty battery.)

Any hint how to get this sync problem fixed??

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Answer 8

KiltedTim

Level 10

225,588 points

Nov 20, 2016 3:17 PM in response to bwadma

There must be a bad calendar entry that's hanging up the sync process on your phone for some reason.

How far back are you syncing calendar entries? Settings>Calendar>Sync. Try cutting it down to the minimum. See if you still have the problem. If you do, there is probably an event scheduled for the future that's messed up. You may have to end up contacting Apple on this one. Tracking down something like a bad calendar entry can be a royal pain, regardless of the platform.

I've ended up completely blowing away people's Exchange accounts to fix similar issues on our corporate mail system. It's rare, but it does happen.

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Answer 9

ChrisJ4203

Level 10

236,297 points

Nov 20, 2016 3:30 PM in response to bwadma

How many other calendars do you share with? Have you tried turning off their calendars and just trying to sync only your calendar? If you truly have 15,000 entries in your calendar, that is going to be monumental to troubleshoot. Since calendar normally will only display 1-year of calendar, that would come out to over 41 events per day average. It would take you forever to try and troubleshoot the bad event.

I would try something like Tim mentions, and try isolating your calendar, making a backup copy of it somewhere and rename it so you can use it again without it being adjusted, and try deleting all of your events prior to November 2016. Try syncing that calendar file and see what happens. Generally, it will be a past event, or a recurring event that will cause issues, at least what I have seen in Exchange before. A recurring event without an ending date used to send Outlook into tail spins in the past.

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Answer 10

ChrisJ4203

Level 10

236,297 points

Nov 21, 2016 6:18 AM in response to bwadma

Did you try removing calendars completely for a short period of time and see what happened? Does that minimize the battery drainage? Then try as I suggested turning on a single calendar at a time? You are going to have to find some way to isolate to be able to troubleshoot, like I mentioned earlier, completely clearing the calendar and trying to create a single calendar with just a few entries. If your calendar does not archive events and remove them from the calendar and you have entries going all the way back to 2011, that could be causing your problem. Those archived events should be removed from the syncing calendar, and you should only have data from the past year available in the active calendar.

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Answer 11

kb1951

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126,083 points

Nov 20, 2016 5:06 AM in response to bwadma

Are you keeping it plugged in to maintain the charge overnight?

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Answer 12

kb1951

Level 10

126,083 points

Nov 20, 2016 2:46 PM in response to bwadma

I only asked because you indicated that the phone lost power at night. Thanks for the clarification that your power drain is continuous during both the day and night.

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Answer 13

bwadma Author

Level 2

164 points

Nov 20, 2016 3:17 PM in response to KiltedTim

Thanks! Will try - set to the minimum of 2 weeks.

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