FIX: Sony Tablet P standby/sleep mode battery drain

[Jenn]

This is not guaranteed to solve your standby battery drain problems (if you're having any), but it's the only thing that worked for me.

After a week of seeing at least 30% battery drain overnight because my Tablet P was being kept awake by the "network-location-cell-update" wakelock, I think I finally figured out what's to blame. I tried disabling radios, changing settings, doing a factory reset, and airplane mode, but nothing worked. No matter what I did, that wakelock was keeping the P awake for hours with the screen off.

At its worst, it kept it in this awake state for 13 hours. At its best, 4 hours.

Now it's down to 17 seconds in the past 17 hours with WiFi, background data, and auto-sync on the whole time.

I still need to see how things go over the next few days, but so far I think the problem all this time has been hiding in the preinstalled AT&T Communication Manager.



See those two options at the bottom: "Enable mobile network" and "Enable AT&T Wi-Fi"? Both are selected by default and if you leave it like that, they'll stay like that. Even in airplane mode, both are still enabled and (based on the wakelock that's been tormenting me) apparently constantly searching for a signal/network/whatever.

Yesterday, after I saw that a factory reset and no third-party apps fixed the problem, I saw those two options and unchecked both just for the hell of it. And as I said above, the wakelock has been reduced from hours to seconds.

I don't know which option is doing the most damage yet, but I'll find out soon. I'm going to leave mobile network checked tonight and see what happens. [see updates below]

[harper]

Can you uninstall it?

[RayIczer]

I wish I could test this out for u, but I am afraid I dont use AT&T

[Jenn]

Okay, "Enable mobile network" is definitely bad. Very bad. I left it on last night and the wakelock I've been complaining about since day one came back and kept the P awake for over 9 hours. Needless to say, it drained my battery by over 50%.

I'm testing it with just "Enable AT&T Wi-Fi" on today.

It seems Gizmodo ran into the same excessive battery drain I was experiencing. Here's a quote from their (very negative) review:

Actual use it didn't drain it so badly, but this thing drains itself out like crazy in stand-by mode. After a bit of light gaming, it couldn't last 24 hours without a plug, and that was with only Gmail and calendar syncing (no Facebook, Twitter, RSS, or anything like that). Weird!

It seems to me that everyone who buys the AT&T version and uses it with a data plan will have this problem unless they manually disable these options in the Communication Manager. Otherwise, even when 3G/4G isn't being used (and the Tablet P is perfectly connected to a home WiFi network), the battery won't make it through the night (and other long periods of standby/sleep mode).

Update: AT&T Wi-Fi appears to cause the same battery drain: 7+ hours of "network-location-cell-update" preventing my device from going to sleep.

[Jenn]

Bottom line:

• Disable "mobile network" and "AT&T Wi-Fi" from AT&T Communication Manager.
• Keep AT&T Wi-Fi disabled at all times; it doesn't affect your regular WiFi radio (I remained connected to my home WiFi network the entire time AT&T Wi-Fi was disabled) and it doesn't seem to have a purpose.
• Turn on mobile network only when you need to use 3G/HSPA+. Battery drain while this is on and the device is in use seems normal.

It seems that whatever radios are controlled by AT&T Communication Manager are somehow different than the radios controlled in the standard Settings > Wireless & networks. I don't understand how this possible, but disabling the radios (and even using airplane mode) through the standard settings does not prevent the "network-location-cell-update" wakelock from keeping the Tablet P awake when it's supposed to be sleeping.

The only way that I've been able to prevent that wakelock from wreaking havoc for hours is to disable the aforementioned options in AT&T Communication Manager.

[FabTabP]

This is a great tip that has worked for me.

One thing I will add is that you may have to reboot the tablet after deselecting the options. Killing your running services doesn't hurt either because something from there could still be running even after you disable it.

This might be why the att wifi option caused battery drain too. I don't think it should by itself but I could be wrong.

[froginmypocket]

Thanks Jenn. This has worked for me but I am annoyed that I have to do it in the first place. AT&T needs to issue a fix pronto.

I agree that a reboot after the options are disabled is best. Otherwise it doesn't seem to work all the time. I had to reboot after enabling mobile network once too because AT&T was complaining that the Sim card couldn't be verified.

This is a good fix but not a permanent solution to the problem.

[growbee]

AT&T WiFi is their free hotspots so maybe if you dont have that turned on, you wont be able to detect them? Sounds like crappy coding to me. I plan to keep it off all the time.

If that option doesnt affect the real WiFi, are we positive that the other option has to be enabled for 3g to work?

[Jenn]

@ FabTab: Sometimes I'll kill "Google Services" in the running services list, as that's the one that seems to affect the wakelock for some reason. So far I've been able to check and uncheck "Enable mobile network" without rebooting in between.


@ growbee: Yes, "Enable mobile network" through AT&T Connection Manager has to be enabled. It'll look like you're connected in the system bar, as "AT&T" and the signal bars will be present, but you won't be able to actually get online until you check that box in the Connection Manager.

[t.w.g]

Hi,


I don't think it is AT&T related! I have the european GSM-Version of the Tablet P and it has the same problem with battery draining.


Any other tips, help? Could be such a great machine but this battery problem is not funny! :-(

[Jenn]

Hi t.w.g,

Is there any carrier-related app that's similar to the AT&T Communication Manager?

Is it the same "network-location-cell-update" wakelock that's preventing your P from sleeping, or is it something else? Once I had some kind of kernel wakelock (I don't remember the exact name) that kept the device awake for 7+ hours, but it hasn't happened again. I do still have some kernel-related wakelock keeping it on for about an hour or so, but I haven't looked into it yet.

Sony needs to release an update to fix this!

[t.w.g]

Hi,

there's no carrier related program on the device.
How do I find out if the cell-update-wakelock process is active or too busy?

[Jenn]

Originally Posted by t.w.g

How do I find out if the cell-update-wakelock process is active or too busy?

Install BetterBatteryStats: http://forum.xda-developers.com/show....php?t=1179809

Select "partial wakelocks" from the first drop-down menu and you'll be able to see the various wakelocks that were active since your last charge (or since you last unplugged the Tablet P). Under the "other" option in that same drop-down menu, you'll also see how long the device has been awake versus how long the screen was on (you're supposed to be able to see this info in the regular tablet settings too, but it always force closes for me). This will help you determine why your P isn't sleeping properly.

BTW, could you add your P's info here? http://forum.pocketables.net/showthread.php?t=11021
[Update: Thanks. I didn't know you had the German version too, though. I thought you had one from the UK for some reason]

[Jenn]

Sony/AT&T really have to fix this standby issue immediately.

Here's a quote from Bloomberg's negative review:

...the charge plunged even when the Tablet P was in standby mode. I left the unit charged but unplugged a couple of times over night and once over a weekend. When I returned to it, the battery was dead.

The fix above works for AT&T versions and has completely eliminated the standby drain for me. It wouldn't change the final verdict of any of the bad reviews, as poor battery life is just one of many complaints cited, but it would at least be one less thing to slam the device for.

[growbee]

Maybe if we all email Sony, they will issue a fix. I bet they dont even know about the problem.

Sent from my Sony Tablet P using Tapatalk