The Truth About Push Email

I have read a number of posts from bloggers explaining about how their WP battery life was vastly improved when they disabled “push” or “as items arrive” email. This appeared strange and contradictory to me, as from what I understand, Microsoft maintains a constant low power connection to every Windows Phone, provided a data connection is active, or the device is being powered while on WiFi. So, as the phone is already connected, all a push message does is tell the phone to ramp up power to receive a new message and popup an alert. No extra power to constantly monitor for new messages. Theoretically, push email should actually be more efficient than; every 15, 30 or 60 minutes, as that method ramps up power whether there is a new message or not.  So I figured, why not test this out and find the truth.

I have five email accounts synced with my phone, three of which can be setup for push email. The other two accounts are setup to fetch mail every 30 minutes or 2 hours. As an FYI, I also have 8 Background Tasks turned on all the time, as well as Data (mostly LTE), WiFi and Location services. Bluetooth is off unless I need it.

TEST 1 – For the first test I left everything as is. The three push accounts were left to receive mail via push. I got my battery charged close to full and set it down on my desk at just about midnight. I woke the phone up after 8:00AM. I sent two of my accounts an email to ensure there was some activity. I received a total of 3 message overnight. The results:  95% at 12:01AM / 77% at 8:02AM – Difference of 18% or 2.25% per hour. Reasonable for me considering that I typically drain 3 to 3.5% per hour with an occasional text or reading a few messages throughout the day. My signal at work is also a tad weaker. Still working on why the 3.5%. But that’s for another article.

TEST 2 – For the second test, all the parameters stayed the same, except my three push email accounts were set to check for mail every 60 minutes. The results: 97% at 12:00AM / 73% at 8:02AM – Difference of 24% or 3% per hour. Looks like I proved my point. But you can never rely on a single test.

TEST 3 – For the third test, I changed my three push accounts to check for mail every 15 minutes, figuring this would represent the worst case scenario. The results: 11:59PM at 97% / 8:00AM at 79% – Difference of 18% or 2.25% per hour. What’s this, an 18% drain again. Same as push. How can this be? More testing required.

TEST 4: For this test I changed my three push accounts back to checking mail every 60 minutes. Let’s see if we can reproduce the first test. The results: 12:03AM at 99% / 8:05AM at 75% – Difference of 24% or 3% per hour. Honest, I am not making this up. Even I was surprised to get the exact same result.

TEST 5: Final test. Reset my three push accounts to “as items arrive”. The results: 12:31AM at 99% / 8:33AM at 83% – Difference of 16% or 2% per hour. Not sure of the 2% difference between this test and the prior push test, but possibly because I started the text with the battery at a higher charge. There you have it though. Verified.

So what does this prove. Well it’s only my anecdotal personal experience, so not sure if it proves anything. Maybe not conclusive but the testing method was objective enough to convince me. I am comfortable knowing that my push email accounts are not draining my battery. And having the battery drain more when set to check mail every 60 minutes sort of validates my theory, although I figured it might only be a couple percent difference. The real mystery though is why did my battery drain more when I set my mail accounts to sync every 60 minutes and the same as push when set to every 15 minutes. Could that be a bug? Sure, testing during the day when emails are flying in would be an ideal situation. But who has the strength to resist touching their phone while it tingles and vibrates for hours. Not me.

Note that for each test, my accounts only received three or four messages overnight. While checking for messages (15, 30 or 60 minutes) should use the same amount of energy whether or not there are any, push could theoretically use more power if you receive messages frequently. For example, if you typically download dozens and dozens of messages daily, turning off push may save you some power. Then again, if you are that important to receive all those messages, you probably want to get them ASAP. 

Not convinced. You can do your own testing, even without Battery Meter. Get your phone fully (or close to) charged and check the percentage in Settings>Battery Saver. Note the time and set the phone down overnight. Wake it up in the morning and note the battery percentage in Battery Saver. Repeat the test the next night with different email settings. But try to keep your charge level, and obviously the length of your test the same. To get a good sampling, you test should be at least 5-6 hours. As with any good testing methodology, removing as many variables as possible will offer the most accurate results. Trying to perform a test during the day; driving to work, moving around your workplace, storing your device in a steel locker, going out for lunch or running errands, will all wildly skew your results from day to day. Static, controlled tests as the only way to derive accurate, comparable results.

First truth: If you want to save battery (or don’t want to use any more), turn on that push email. And if you have mail checking set to 1 hour, change it. At least for now till someone can verify if there is really a problem. I am planning a series of Truth posts to give users a better understanding of how their battery drains. Background Tasks, Battery Saver, LTE vs. Edge, Email on/off and Feedback are all on the list. Any suggestions?