Screen CaptureTabs-Square

To conclude my Truths series for Windows Phone I wanted to check into an area that has bugged me for several weeks. Anyone who has been reading my test results knows that I have occasionally encountered anomalies, results that were worse than expected. I usually countered the odd duck result with a couple consistent values to be sure the exception was not really the rule. I still don’t know what’s responsible for these unusual drains, but one of the suspects have been open tabs in Internet Explorer. Before starting a test I would usually back out of all tombstoned apps and check IE for any open tabs and close them. Wanted to have that consistency between test results. A few times I did forget to check and left tabs open. On more than one of those occasions, the result turned out to be a higher than expected overnight battery drain. Coincidence, or a bug. Only one way to find out.

To recap, my phone (Lumia 900) is setup with the following:

  • – Data (mostly LTE) and Wi-Fi ON – Bluetooth OFF
  • – 8 Active Background Tasks (3 Internal)
  • – Location Services ON
  • – 5 Email accounts syncing (3 push, 1 every 15 minutes, 1 every 2 hours)
  • – Phone set down and untouched for a 8 hour period

My previous baseline tests have resulted in an 16%, or 2% per hour, battery drain in an overnight 8 hour test. For clarification, my Background Tasks include; USA Today, Fox News, Weather Channel, Mehdoh, Urban Dictionary, Network Dashboard, Clever-To-Do and Battery Meter (a homebrew app set to update every 10 minutes).

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Test 1 – Before setting my phone down for testing, I opened IE and opened 6 tabs. I tapped the Back button to remove the open pages from the multi-task view. I reopened IE one more time to verify that all 6 tabs were still active within the application. Backed out again and set the phone down. The results; 100% at 12:34AM / 80% at 8:34AM – Difference of 20% or 2.5% per hour. Interesting, a 4% higher result than my baseline. But one test is never enough.

Test 2 – Same setup as Test 1. The results: 100% at 1:16AM / 88% at 9:16AM – Difference of 12% or 1.5% per hour. Wholly mAh savings Batman! That’s the lowest result I have ever gotten in an overnight test. No idea how that happened. But I do have another suspicion, one that I may never be able to prove without picking a brain at Microsoft. I suspect that sometime between 12:00AM and 1:00AM, my phone does a sync with Marketplace to check for updates. With nearly 200 apps/games, I get updates at least 3-4 days per week, and they almost always appear by about 1:00AM. Presuming this is the case, and being that I didn’t take my phone off charge till about 1:12AM for this test, the Marketplace scan might have already concluded, hence the smaller overnight drain. Just a theory mind you. And with only 10 or 20 apps, a typical user might not notice the battery hit. Another Microsoft assumption would be that most phones are on overnight charge by 12/1:00AM. Of course, if app information is all stored and compiled on some server and only an update notification is pushed to my phone, then my theory is a bust. The other, less complicated, theory would be a simple variation in cellular signal on certain nights cause by the weather, or who knows what else.

With two odd results though testing was far from complete.

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Test 3 – Same setup as Test 1, except I decided to leave five apps tombstoned; a couple IE pages, my Favorites folder app page and a couple others. Might as well kill two myths with one test. The results: 100% at 12:36AM / 84% at 8:36AM – Difference of 16%, or 2% per hour. Ok, now we are getting somewhere. Can I have another.

Test 4 – Same setup as Test 3. The results: 100% at 12:44AM / 85% at 8:44AM – Difference of 15%, or 1.875% per hour. That’s more like it. It looks like my IE Tabs theory, along with tombstoned apps, have no effect on your battery. Going to be hard to break my OCD habit of always backing completely out out everything. Time to make better use of the Start button. But while I am testing tombstoned apps, one more scenario wouldn’t hurt.

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Test 5 – For this final test I opened five apps that generally use, or try to use Background Tasks; Skype, iHeartRadio, IMDb, SuperTube and Yelp. If tombstoned apps are really tombstoned, they shouldn’t use any battery power, right? Before starting the test I tapped the Start button to put all five apps in a tombstoned state. The results; 100% at 12:19AM / 85% at 8:19AM – Difference of 15%. or 1.875% per hour. So there you have it. BTW, Yelp did launch it’s Background Yask, without my permission. IMDb has done the same a couple times. Oh, and BTW2, with Skype and iHeatRadio both running in the background, persistent WIFi was active during the test.

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Ninth Truth – Keeping  IE Tabs or Tombstoned apps open in the background appear to have zero effect on your battery. So forget about that Back button and just keep opening whatever you want. Microsoft has you covered.

 

I have enjoyed bringing you some insight into these battery drain myths and theories. But I honestly look forward to playing with my phone each night into the wee hours and then letting it charger properly overnight. Giving it up to the testing lab every night at around 10:00pm, till 8:30 each morning has been a real drag. Although this round of testing has concluded, don’t think for a second that I won’t continue to try and figure out what causes the occasional increases in battery drain. I can’t help myself.

4 COMMENTS

  1. What about web sites that auto-refresh? For example, the local transit authority’s web page for bus schedules includes a script that reloads the page once every minute or so. Several times after getting on the bus I forget to close that tab, only to later find that my battery suffered hugely! Of course I see the page has been updated to within a minute of my picking up the phone, even though I had not touched it for 30 minutes. So it is clear that the refreshes were happening in the background. If someone did this on a big page that auto-refreshes (like slate.com) I imagine huge battery losses.

  2. Interesting Bob. If you (or someone) could find me a couple sites that auto-refresh I would be glad to give it a go.

  3. […] – Phone set down and untouched for a 8 hour period Continue to read the full story… […]

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