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Battery Low Real Cause of battery drain/wake lock in MJ7/MK2 and fix

OP mongoose3800

5th January 2014, 04:31 AM   |  #1  
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I am posting this as it is very hard to wade through information in forums. I'm hoping the following will be useful to those, who like me, experienced battery drain caused by Android Wake Locks after upgrading to MJ7 / MK2.

I am 100% certain the battery drain in MJ7/MK2 is caused by connecting to WIFI networks in environments that have multiple AP's. i.e. once WIFI roams from one AP to another the battery drain starts. All my testing confirms this - consistently. I have actually tested being connected to one AP in a multiple AP environment for a long period and observed no wake locks on Android OS. Yet as soon I move to another location (i.e when I make it roam) the wake lock and battery drain starts. All this rubbish about clearing cache, factory resetting, nobbling your phone and so on are all stabs in the dark - It's the reboot that temporarily fixes it so people mistakenly put two and two together. So, if you use WIFI in a large building with multiple AP's try forgetting the network and not connecting to WIFI with multiple AP's. If you have already connected to a SSID with multiple AP's reboot your phone because once the battery drain starts it does not seem to stop until you reboot. You don't have to disable WIFI at all as scanning does not cause the wake lock. I have tested this thoroughly and so far I have not had any battery drain since not connecting to SSIDs with multiple APs. I can also back this up as I can create battery drain at will by simply connecting to a WIFI environment with an SSID distributed over multiple AD's.

My battery life is again fantastic and I am happy now that I know the cause.

Pretty poor testing by Samsung/Google as I see in past versions of Android Roaming has been an issue.
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6th January 2014, 02:47 AM   |  #2  
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Quote:
Originally Posted by mongoose3800

I am posting this as it is very hard to wade through information in forums. I'm hoping the following will be useful to those, who like me, experienced battery drain caused by Android Wake Locks after upgrading to MJ7 / MK2.

I am 100% certain the battery drain in MJ7/MK2 is caused by connecting to WIFI networks in environments that have multiple AP's. i.e. once WIFI roams from one AP to another the battery drain starts. All my testing confirms this - consistently. I have actually tested being connected to one AP in a multiple AP environment for a long period and observed no wake locks on Android OS. Yet as soon I move to another location (i.e when I make it roam) the wake lock and battery drain starts. All this rubbish about clearing cache, factory resetting, nobbling your phone and so on are all stabs in the dark - It's the reboot that temporarily fixes it so people mistakenly put two and two together. So, if you use WIFI in a large building with multiple AP's try forgetting the network and not connecting to WIFI with multiple AP's. If you have already connected to a SSID with multiple AP's reboot your phone because once the battery drain starts it does not seem to stop until you reboot. You don't have to disable WIFI at all as scanning does not cause the wake lock. I have tested this thoroughly and so far I have not had any battery drain since not connecting to SSIDs with multiple APs. I can also back this up as I can create battery drain at will by simply connecting to a WIFI environment with an SSID distributed over multiple AD's.

My battery life is again fantastic and I am happy now that I know the cause.

Pretty poor testing by Samsung/Google as I see in past versions of Android Roaming has been an issue.

Funny thing is that when i am using mobile data the drain is worse, So I'm pretty sure this is not the main issue man. Also, I have a Mobile 'WiFi' router. Only me has WiFi connection in my entire hostel. So I don't really think it's the issue. Good finds tho! It will definitely help someone. Cheers!
6th January 2014, 03:20 AM   |  #3  
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Agree with stanley, this is not the only cause.
6th January 2014, 04:07 AM   |  #4  
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Quote:
Originally Posted by vndnguyen

Agree with stanley, this is not the only cause.

Agreed. There are many things that will cause elevated use. But Im talking the rapid drain that occurs when you're not using the phone. Ever since taking the action I describbed my battery life has been excellent. Eg 94% after 14 odd hours with no use. And, I'm still connecting to my home wifi. Beforehand it could be below 60% with no use and this is the real problem people are talking about. Hope that makes sense.
Last edited by mongoose3800; 6th January 2014 at 04:14 AM.
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6th January 2014, 09:24 PM   |  #5  
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Actually it's the opposite. If you set up your modem to have a separate AP for the phone and isolate it from the rest of the network, you'll have much better battery life on wifi because you'll stop your phone from waking up by broadcast packets.
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7th January 2014, 02:04 AM   |  #6  
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Originally Posted by aydc

Actually it's the opposite. If you set up your modem to have a separate AP for the phone and isolate it from the rest of the network, you'll have much better battery life on wifi because you'll stop your phone from waking up by broadcast packets.

I don't get it. What am I supposed to do exactly?
7th January 2014, 06:44 PM   |  #7  
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Quote:
Originally Posted by aydc

Actually it's the opposite. If you set up your modem to have a separate AP for the phone and isolate it from the rest of the network, you'll have much better battery life on wifi because you'll stop your phone from waking up by broadcast packets.

What about unicast traffic? i know the Client Isolation sort of "VLAN"s every client associated, just wondering if that might affect client to client communication?

Good point btw, im also wondering how many services wake the damn thing up, waking up over network is more an enterprise workstation scenario...to me it sounds like HotSpot 2.0 services being active, but i have not enabled it.

HS2.0 can let client and AP sort of talk without associating.
7th January 2014, 06:52 PM   |  #8  
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Quote:
Originally Posted by Nazty111

I don't get it. What am I supposed to do exactly?

Most modems have a sort of 'guest mode' or allow you to open another access point and isolate it from the rest of the network. If you connect your phone to this guest access point or isolated access point, your phone will reach internet without problems, but will not reach the local network through the router. Nor will any other device on the network reach your phone.

Most of the problems with Wifi draining battery, like wifi wakelocks, occurs because devices on the network keep sending packets to the phone waking it up. With the method I describe above, you will isolate your phone and the phone will remain in deep sleep, significantly increasing battery life.
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7th January 2014, 07:04 PM   |  #9  
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Quote:
Originally Posted by aydc

Most modems have a sort of 'guest mode' or allow you to open another access point and isolate it from the rest of the network. If you connect your phone to this guest access point or isolated access point, your phone will reach internet without problems, but will not reach the local network through the router. Nor will any other device on the network reach your phone.

Most of the problems with Wifi draining battery, like wifi wakelocks, occurs because devices on the network keep sending packets to the phone waking it up. With the method I describe above, you will isolate your phone and the phone will remain in deep sleep, significantly increasing battery life.

This is very true. Back on my old GNex i used to have crazy wifi wakelocks and I couldn't for the life of me figure it out. I never figured it out, actually. But I am positive it is one of the two PC's on my network that are broadcasting packets across the network, waking my phone up. I haven't had time to extensively test the wifi wakelock in the environment i've previously encountered it in to see if it still applies, but since I haven't changed anything regarding any of the two computers involved on that network, I'm positive I will have the same wifi wakelock issue when I get back and test. Is there a way (besides using Shark) to see what programs are broadcasting packets across the network?

But to get back on topic, I am experiencing battery drain connected to ONE router with ONE AP. I am in an apartment building with several other routers nearby, though. Maybe they are broadcasting packets somehow that the kernel is interpreting and keeping the phone awake? However it seems as though the Android OS bug keeps coming back for everyone no matter what, even in airplane mode.
8th January 2014, 03:35 AM   |  #10  
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Wifi has evolved a lot the last decade, not just by technology standards but into integration as well. carriers use them as small cells, we'll see them more often in the future (malls, stadiums, etc), and HS2.0 adds to make it a bit more seamless, they call it offload, taking your data needs through small wifi cells rather then the macro cells (3g, 4g), hence offload.

my point is that they would have never invested in that if the wifi chips inside consumer products were not efficient enough, so nearby APs shouldnt be a problem at all. But im still puzzled for what would one need the waking up process through wifi?

If Wifi is the general bugger, then somebody throw an eye on the Passport service, thats the consumer name for HS 2.0 services.

PS, tested AP Isolation on my sh!tty WRT120N, no difference unfortuantely.

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