Cwa-app-ios: sometimes 10% battery capacity usage per hour

[mss1010]

Avoid duplicates

• [x] Bug is not mentioned in the FAQ
• [x] Bug is not already reported in another issue

Describe the bug

In some situations, the battery usage of the exposure framework is extremely high. In these screenshots you see the behavior. The curve is very steep here, while the device was mainly in standby and not used.
In some hours, the battery was drained by approx. 10% overall by exclusively the the exposure framework.

So, far this happened twice, but only on my iPhone 7. But I don´t know, which special conditions were related. Connectivity is always available either via WiFi or cellular LTE.

Expected behaviour

Steps to reproduce the issue

Technical details

• iOS Version: 14.2
• Device: iPhone 7
• app version: 1.7.1

Possible Fix

Additional context

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Internal Tracking ID: EXPOSUREAPP-1882

[Ein-Tim]

See also: #671 and #912

Just a small remark:
If you do not use your phone, than it makes sence that "Begegnungsmittelungen" is the only "App" (=100%) which is shown in these screens...

Edit: I think this can, just like #912 back then, be closed as a duplicate of #671.
Also the reminder from @jucktnich is a good one.

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If you like to (@mss1010) you can share

• the battery health
• is this the original battery
• is there any phone you know of near your phone which constantly shares RPIs?

[jucktnich]

Just a small reminder:
The cwa can NOT influence the battery usage of "Begegnungsmtteilungen".

[mss1010]

See also: #671 and #912

Just a small remark:
If you do not use your phone, than it makes sence that "Begegnungsmittelungen" is the only "App" (=100%) which is shown in these screens...

That’s basically true, but if the battery consumption is 10% in one hour.
A „normal“ consumption chart has a much flatter curve like this:

[mss1010]

See also: #671 and #912

Just a small remark:
If you do not use your phone, than it makes sence that "Begegnungsmittelungen" is the only "App" (=100%) which is shown in these screens...

Edit: I think this can, just like #912 back then, be closed as a duplicate of #671.
Also the reminder from @jucktnich is a good one.

I don't think it will make any sense to further investigate this, but if you like to (@mss1010) you can share

• the battery healt
• is this the original battery
• is there any phone you know of near your phone which constantly shares RPIs?

Im aware of the other issues, but it‘s not a duplicate because the behavior is very different. Im not complaining about relative, but about absolute consumption of 10% battery capacity per hour.

I know that its not directly influenced by the app, but I was hoping that the developers can use their contacts to apple to address this.

[jucktnich]

I think apple knows this issue. You can eventually help them by open a ticket under feedbackassistant.apple.com and attache the iOS Systemlog.

[Ein-Tim]

@mss1010

Yes you are right...
I just checkd an iPhone 6s which is mainly laying around and not used, the ENF does not drain the battery at all on this phone. So maybe it is worth to take a look at your case, even though it might be a edge case.

You can do what was proposed by @jucktnich, but it's also the task from the devs to talk with Apple about this. (Discussion about this back then: https://github.com/corona-warn-app/cwa-app-ios/issues/671#issuecomment-696099259)

Sorry for my not so nice reaction 😅

Have a nice evening

[ndegendogo]

See also here for related observation on Android.

[ndegendogo]

The cwa can NOT influence the battery usage of "Begegnungsmtteilungen".

(via @jucktnich

Well - we don't know how this number is measured.

One part of ENF functionality is sending and receiving RPI - this is definitely out of control of cwa.
The other part is the calculation of matches.
We don't know if this counts towards cwa or towards ENF. My own numbers suggest it might be the latter, at least if it is triggered from background. But of course we don't know, to be answered by Apple.

[ndegendogo]

And if we assume that risk checks from background count towards cwa, then the change from 1 daily check to 5-6 checks per day since cwa 1.7 could maybe explain higher consumption now.

[mss1010]

If you like to (@mss1010) you can share

* the battery health

* is this the original battery

* is there any phone you know of near your phone which constantly shares RPIs?

• battery health is 95%
• it´s the original battery
• yes, but this is the case all the time. But only on some days the high consumption happens

[jucktnich]

@ndegendogo cwa also can't influence matching numbers...

[ndegendogo]

I just checkd an iPhone 6s which is mainly laying around and not used, the ENF does not drain the battery at all on this phone.

@Ein-Tim interesting.
Could you please give a few more details? (Just for comparison): cwa version? iOS version?
Is background check working on this device?
How regularly? Is it connected to WLAN? (So with current cwa 1.7.1 we would assume 5-6 checks per day - yes?)

[ndegendogo]

cwa also can't influence matching numbers...

@jucktnich correct. But one check per day (pre-cwa 1.7) or 5-6 checks could make a difference

[jucktnich]

Yes, but what's the clue for the developers? Should they offer a setting to disable multiple checkings per day? That would be, i think, the only way to decrease battery usage.

[Ein-Tim]

For sure @ndegendogo

• CWA Version: 1.7.1
• iOS Version: 14.3 Public Beta RC 2 / Build: 18C66)
• Background checks working reliable (4-5 checks per day)
• Connected to the internet via WiFi
• Not used at all

I definetly think that the Battery is drained faster because of the ENF. But I never expierienced spikes like @mss1010 reported...

[Ein-Tim]

@jucktnich

The clue for the developers is that the user will not make a difference between ENF and CWA and if the phone gets empty to fast, because of "the App", the user will deinstall it.
See also this discussion: https://github.com/corona-warn-app/cwa-app-ios/issues/671#issuecomment-696109490

[ndegendogo]

Should they offer a setting to disable multiple checkings per day?

@jucktnich excellent idea.
Of course, I know, many options will make usage more complex ...
But many people prefer more control how they want to setup their preferences, and are unhappy with "one size fits all".

Examples:

• some are happy with one check per day in favour of battery consumption
• some prefer multiple checks per day and don't care so much about battery (this is me!)
• some prefer one check per day if not in Wifi, and don't want to pay extra data volume
• some prefer multiple checks even using mobile data (again: me)

[Ein-Tim]

@mss1010 (and everybody else), maybe you could monitior if something has changed with v 1.9.1 and v2 of the ENF.

[itinance]

I face a similiar issue. A new iPhone 11 Pro is discharging 100% over night, while my 2 years old iPhone 10 remains fully charged. The only difference is that the new iPhone 11 has CWA installed. I spot this issue since some days now.

All PNS are disabled, across all apps. Almost all background services are disabled as well (it is enabled for CWA, though). But overnight it gets discharged since some days.

iOS 14.2
CWA: 1.10.1

[jucktnich]

What's the "Batteriezustand" on the iPhone 11?

[Ein-Tim]

@itinance

Is there any other device with an installed Corona-Warn-App near the iPhone 11?

[itinance]

@jucktnich

What's the "Batteriezustand" on the iPhone 11?

Battery Health -> Maximum Capacity: 99%

@Ein-Tim

no. No other device next to it at night running CWA (my wifes fone is complete off during night)

I just see almost every night a constant drop in battery capacity from 100 to 0.

[jucktnich]

Did you tried to reboot the device?

[Ein-Tim]

Interesting. Is "Exposure Notification" responsible for 100% of it?
("Battery" and look at the text under the diagram)

[itinance]

Exposure Notifications: 46%.

While alle other services are single figures.

[Ein-Tim]

Okay thanks.
Could you update to iOS 14.3 and report back after monitoring for some time?

[itinance]

@jucktnich i will reboot todays evening and see what is happening then during night (now at day time it makes no sense due to heavy usage including personal hotspot)

[itinance]

Okay thanks.
Could you update to iOS 14.3 and report back after monitoring for some time?

Alright! Many thanks for this conversation!

[dsarkar]

Internal Tracking ID: EXPOSUREAPP-1882

[thomasaugsten]

@itinance is your iPhone 11 Pro still discharging 100% over night?

[itinance]

@thomasaugsten

@itinance is your iPhone 11 Pro still discharging 100% over night?

Unfortunately Exposure Logging has disabled during Wednesday Night for unknown reasons. I just noticed it todays morning and re-enabled it.
However, iOS 14.3 is installed since 2 days and todays night I will check again and tell here the results tomorrow.

[Ein-Tim]

Any update @itinance or do you want to monitor a bit longer?

[itinance]

Any update @itinance or do you want to monitor a bit longer?

Yes! No significant battery drop last night. 4% energy consumption over last 24 hours.

[Ein-Tim]

What about you @mss1010?

[mss1010]

I did not see the issue anymore. We could close the issue if you like

[Ein-Tim]

For sure. 👍
As the author of this Issue you can go ahead and close it.