Nexus 7: Battery drain and CPU usage bug found in 4.4.2

jerrykur

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A bug activated by Skype and other applications in 4.4.2 is causing high battery drain and overheating. It looks like the bug is in the camera software. Maybe this is the root cause of the crashes and reboots some people have seen when using the Nexus camera. There is a fix from Google coming for Nexus devices. If you are not on a Nexus device, then you still may have the issue, but the fix has to come from the device's manufacturer.

It sounds like the bug is related to the chipset and effects other devices with earlier release of Android. Specifically the article mentions the Note 3 with 4.3

KitKat giving you battery drain problems? Try uninstalling Skype, says Google as it prepares a fix | ZDNet
 
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patchs

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Re: Battery drain and CPU usage bug found in 4.4.2

I have Skype on my Nexus 7 but the app isn't open. I'm not logged on either. Does that make a difference? Should I uninstall Skype?
 

srkmagnus

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Re: Battery drain and CPU usage bug found in 4.4.2

I have Skype on my Nexus 7 but the app isn't open. I'm not logged on either. Does that make a difference? Should I uninstall Skype?

Do I have to use the camera in order for the random reboots to occur?

I'm pretty sure there are specific conditions that cause the bug to drain battery. You can check your battery stats to see if you are affected - there will be a process with Camera listed and have high useage. It's not limited to just Skype, it's any app or service that calls up the camera.

Sent from my Nexus 5 using AC Forums mobile app
 

Jon_Doh

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Re: Battery drain and CPU usage bug found in 4.4.2

I've never had Skype on my device and my battery still drops like a bomb. I agree something in the OS is running because battery monitor apps report high OS usage when it's sleeping, but it ain't because of Skype.
 

jerrykur

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Re: Battery drain and CPU usage bug found in 4.4.2

I've never had Skype on my device and my battery still drops like a bomb. I agree something in the OS is running because battery monitor apps report high OS usage when it's sleeping, but it ain't because of Skype.

The article says Skype is just one of the apps. It has to do something with apps that start the camera. You might have another app which uses the camera service.
 

patchs

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Re: Battery drain and CPU usage bug found in 4.4.2

I just charged my N7 (2013), it's 100%.
There are no apps open, the wifi is on. The screen is off obviously. I'm heading to work soon, wonder what the battery level will be when I return?
 

patchs

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Down to 73 %. That seems a lot since it was just sitting there, no apps open or screen on, just wifi on, checking email or weather widgets

Posted via Android Central App
 

Relgoshan

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Down to 73 %. That seems a lot since it was just sitting there, no apps open or screen on, just wifi on, checking email or weather widgets
Posted via Android Central App

It's disastrous! My tablet may soon be getting the 4.4 update and right now I do not plan to take it. You should lose *less than 1% per hour* on wifi.
 

Relgoshan

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Down to 73 %. That seems a lot since it was just sitting there, no apps open or screen on, just wifi on, checking email or weather widgets

Posted via Android Central App

https://www.dropbox.com/sh/fh16m0daxxyfhf4/56TnCwP9EU

You lost 27% battery in 10.5hrs of pure idle?? I lost 17% in 28hrs including 30min of browsing. That amounts to FIVE DAY life if you go online for an hour or less a day, never shutting down or even turning the radios off. Sheer standby should hit close to 10 days or more especially with the radios off. I don't know about the 15+, it seems like a useless number. But an hour a day for most of a week is pretty good.

Your N7 should be miles more efficient than demonstrated, esp if wifi is the only active radio. That battery performance is what I would expect from a $100 wal mart tablet.
 

gerryp123

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Down to 73 %. That seems a lot since it was just sitting there, no apps open or screen on, just wifi on, checking email or weather widgets

Posted via Android Central App

Wondering what the result would be for the same test with wifi turned "off"
 

patchs

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Basically exact same results yesterday, 100%, no apps open, wifi on. 9 1/2 hours later, 72%
I'll do it again today but with the wifi off.
 

jerrykur

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Basically exact same results yesterday, 100%, no apps open, wifi on. 9 1/2 hours later, 72%
I'll do it again today but with the wifi off.

How about posting to your battery details screen. Also, what apps do you have installed? Anything that updates and/or monitors (ex. news, twitter clients, etc.) are possibilities. Also, is your wifi connection good? A poor connection that drops and reconnects constantly can kill a battery quickly.

FWIW, Apps can run even if there are not displayed, or an app can invoke a service that will run with no UI. Both of these cases consume power.
 

patchs

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With tablet in airplane mode, 76% battery left after almost 10 hours. That's unbelievable

Posted via Android Central App
 

gerryp123

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Battery drainage seems indeed high. After 10 hours in "sleep mode" (wifi off) I would expect no more than a 5% drop. (Only one time have I've seen my battery charge drop ~20% overnight, but that situation seemed to correct itself the next day). I assume that during the sleep interval no apps were running (all usage was from Android itself) and that wake-locks were few.

A bit of a mystery - but life goes on. Buy a wireless charger and get in the habit of charging unit is when idle!
 

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