Stream Tablets Standby Battery Drain Workaround

[jleblan1]

I posted this as a reply in another topic related to standby battery drain, but figured it could use its own thread.

The culprit for the terrible standby battery drain is the Intel SST Audio driver. It doesnt allow the tablet to fully sleep therefore draining the battery.

The simple workaround is to lower the tablets volume to "0" with the volume rocker before putting your tablet to sleep. This will dramatically improve the stanby battery life from hours to days. I lose about 1.5-2% per hour in standby with the volume muted.

Im working on a scheduled task script that will mute the volume upon sleeping and unmute upon wakeup. If I can create one I will post it here.

[rfruth]

Good to know, wonder if the SST driver will be updated to correct this (if it can be) 

[darrenc]

After a bit of experimenting I can add another suggestion that may help some people out a bit if they use bluetooth for audio. In my case most of the time I do use a bluetooth headset. Since the headset/windows pairing handles its own volume, that volume is independent of the rocker switch. The rocker switch will change the volume, but as long as the headset is attached of course the headset can handle its own volume. I can pair up my headset with the volume still at 0 on the rocker, and my headset volume takes over. Once I unpair the headset, the volume returns to 0 automatically. Somehow in my mind I assumed the main rocker volume would supersede everything and if it was at 0 the bluetooth would be also, but it doesn't do that.

As a result, I don't have to worry about constantly dropping it back down when I stop listening to audio as long as it was already at 0 when it paired with the headset. I can get the full battery benefit of the device actually sleeping and still hear audio without ever having to change the rocker switch.

And for anyone who may be interested, if you open an admin command prompt and run powercfg /energy it will show you anything that is preventing sleep. Just let the command run its course and then open the html file it will generate. Near the top will be red boxes with things that are effecting your specified energy settings. With your volume above 0, you'll see an entry that the SST audio driver has requested to prevent sleep. With the volume at 0, that entry disappears. And google tells me this has been an issue with that device for almost a year now, so it's probably not going away anytime really soon.

And the difference it can make is pretty dramatic. Having my volume set at 0 on the rocker my Stream 7 has been off the charger and running or sleeping for 20 hours now and my battery is still at 42%. My normal usage isn't too demanding, so under a heavy load of course it wouldn't hold up quite that well, but I do use it for listening to music at least a few hours a day and some web browsing and MS Office stuff. Previously, though, the longest it's ever lasted without needing the charger is about 6-7 hours, with maybe half of that while supposedly sleeping (it could make it about 9 hours overnight if supposedly sleeping the entire time on about 80% of the battery). Now I have no doubt it will make it 24 hours with my normal use before the battery must be charged.

[jeffmdaemon]

Well son of a... so not only does the audio chip have crappy quality audio, but its draining our batteries to hell and back. 

[jleblan1]

Found a little utility that will help if you forget to mute before putting device to sleep.

http://auto-mute.com/download/

This issue has existed on intel atom devices for over a year, you'd think they'd patched it by now. It could hurt windows tablets in the long run with bad reviews of battery life.

[jeffmdaemon]

Well I went to sleep leaving the tablet at %20 and woke up to a dead tablet, so something else killed it. Going back to shutting it down when not using it. 😜

[darrenc]

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@jeffmdaemon wrote:

Well I went to sleep leaving the tablet at %20 and woke up to a dead tablet, so something else killed it. Going back to shutting it down when not using it. 😜

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Check what apps are allowed to run in the background and see if anything there might be doing a lot of updating and such (launch the PC settings app, tap the 'lock screen' section and scroll down to see the apps that can run in the background - with mail, weather, calendar, alarm and skype mine holds up great overnight now).

Also try the powercfg /energy command and see what it reports.

[jeffmdaemon]

So I did the energy log, all is well accept that it looks like my router does not support low power modes. This may actually shed some light on the wifi issue for some.

Anyways, I then did a sleepstudy. Bingo. It brought up what little sleep activity I had it do in the past 3 days.. the biggest block being last night (well.. 2 am this morning). I had been watching web video on it and so in a grey line it showed a sharp decline. Then it went to sleep and showed a not as sharp, but still a very rapid red line showing the tablet was in standby but was very active. 

The single offender being active %99-%100 of the time was UART controller, (/_SB.URT1). Everything else was %2 and under. After a quick search, it appeared that surface tablets would have a uart sleep issue if bluetooth was turned off. And while it was turned off in the past, I went to it just now and it was on, so it was on all last night too. 

[darrenc]

I guess I'm just turning out a bit lucky with it.  Here's what my sleep study shows for last nights sleep session.  I don't think it could really be any better.  In 6 hours and 40 minutes it used 6% of the battery.  It only came out of CS for 13 seconds and Wifi High Performance was disabled for all but 5 seconds of that time.

[jeffmdaemon]

So after doing some testing the past several hours I have come to this conclusion about UART,

When using connected standby;

1) UART rains battery at a huge rate when BT/Wifi is enabled. 

2) UART drains at a huge rate when BT is turned off and wifi is left on. 

3) Nothing happens when airplane mode is activated, sleepstudy showes everything at %0 and the battery didnt drop at all over 2 hours. 

So if i had to point fingers at anything, it is a wifi issue. I tried uninstalling the bluetooth radio and letting it reinstall too (because past UART issues were a bluetooth bug when it was OFF) but it changed nothing.