For those of us fortunate enough to have access to an LTE market area, we know how exciting it is to finally be able to download/upload data with ease. The Carriers love it as they can quell the complaints about their slow networks (at least for a while anyway) and have an opportunity to add up charges when you easily exceed your monthly data limits. So with all this magical speed, does LTE have a downside? Well, yeah.

It frustrates me when I ready about users and their battery life experiences ranging from incredibly fantastic to incredibly bad, often with the same device. While there is always the possibility of variables, like signal strength, that can significantly affect a users battery experience, the way they use their device from day to day usually explains the anomalies away. Fortunately for you, I am pretty boring and stick to a basic routine every day. I use my device in the same location(s) for  approximately the same thing, and for the same amount of time. While my results are admittedly anecdotal, they are as close as you are going to get to accurate without a full blown lab test. Something I am sure each Carrier has already done, but is guarded in the Carrier Book of Secrets.

My basic routine includes unplugging my phone every morning , sitting on the same stool (no, not that stool), and then using it for 1.5 to 1.75 hours to; read any overnight texts or emails, browse the MD site via IE, open Weave and read all the new mobile news and then open Board Express to read  and comment in a few blogs. Phone never turns off and all in that specific order. On slow news days, I might open Mehdoh to read a string of tweets. Or, on a really slow day, open the People Hub to read some Facebook posts. That’s it. Most of the work day my phone stays holstered, or I may  occasionally gaze at a few emails or a text if I am hearing a bunch of alerts. This routine gives me a good indicator of uptime and sleep time battery drain. Consistent, and therefore reasonably accurate.

As I have a good Wi-Fi connection both at home and at work, I leave Wi-Fi turned on 24/7. In overnight tests I have found that Wi-Fi draws virtually no power while asleep, as it’s not active or searching. So provided you have a reasonable connection a good part of the day, it’s not going to have much of an impact on battery life. My other reason for using Wi-Fi, despite having a grandfathered Unlimited AT&T Data Plan, was the abysmal 3G connection I got both at home and work with my Surround. But with my new Lumia 900 and LTE, that is no longer an excuse. So I decided to go LTE only for a few days to see if I could wean myself off of the Wi-Fi habit.

Having an unlocked device and the (Homebrew) Battery Meter app helps with testing battery usage. I can see where I am at a glance and I can view the provided graph anytime, showing me a battery percentage update every ten minutes. Over the past month, my  morning routine equated to about 13% battery drain per hour of uptime, with both LTE and Wi-Fi turned on. That is about right as the L900 is rated for 7 hours talk time and typically uptime (screen on) will be a little better than talk time (100% / 13% = 7.69 Hours). At least this has been the case with my last 4 phones. When I decided to use LTE only, battery usage over five days of testing jumped to an average of 19% per hour. Holy gluttony Batman! That’s an increase in battery drain of 46%!  Note that I always have  3 or 4 bars of LTE inside the house with speeds around 10-12Mbps down and 3-5Mbps Up. That may be a “poor” signal in LTE Speak, but seems above average to me. When I returned to the LTE + Wi-Fi setup, battery drain went back down to 13% per hour. Email syncs, background tasks, Location on, etc. have all been about the same since of got my L900 so no variables to skew the results.

Note that  the percentages above are based on the L900 and it’s 1,830mAh battery. Every phone will have a different percentage of drain per hour, based on their battery size. My Surround, for example, drained about 21% per hour of uptime (100% /  21% = 4.76 hours – rated at 4hrs 10 min Talk Time).

On the flip side, sleep time with LTE only or Wi-Fi/LTE (occasionally turning the phone on to read a quick text or email) both burn about the same 4% per hour. Only get 2 to 3 bars of LTE at work, so that might explain the 4% drain. But I am also zeroing in on a couple Live Tile News apps and Location services being the culprits.

So what’s the moral here. If you have access to Wi-Fi most of the day, keep it on. And keep your LTE on as well.  Keeping both on you can still get background updates but enjoy the lower power drain that Wi-Fi offers. And you will still be good to go with LTE when you spend a night out on the town. Just remember to charge your phone before you go.

2 COMMENTS

  1. Curious about recommendation to keep LTE on. Have you tried turning LTE (4G) off using the Data Field Test screen (from your post last week), keeping 3G on, and compared drain rates?

    There’s a popular perception that LTE uses more power than 3G. Not sure if that is power per bit (unlikely… LTE should be efficient, right?), or overall average power including overhead, searching for signal/tower, etc. But it seems like you should have the tools to investigate knowledgeably.

  2. EddyKilowatt: Actually, my plan was to test using Edge w/WiFi, which I am guessing may be the most efficient combination (when you have a good WiFi signal available). But the day I started my test, the homebrew Battery Meter app, that I rely on for results, went offline (background task disabled) several times. After some investigating I discovered that it was a conflict with the Battery Meter app and a new version of the (homebrew) Folders app, that I installed on the same day. Got to love that homebrew stuff and the way things can get messy in a hurry.

    The Folders developer is working on a fix, but in the meantime I know what to look for to prevent Battery Meter from going offline (can’t have Folder active in multitask view) so I can resume my testing. I can say that in the brief period (a good part of a day) I did have Edge active, sleep time drain seemed to be about the same as with LTE. But I will need to do 4 or 5 days of testing, throwing out the anomolies, and working up solid averages before I have a clear conclusion.

    Regarding setting to 3G, I belive that the 3G switch on the Lumia 900 actually results in a 4G, HSPA+ signal. At least that’s what the speed results are indicating. So not sure, if there would be any radio power savings. But I may give it a shot after my Edge testing.

    I guess the point of this article was than while sleeping, it seems like LTE goes into a deep sleep state burning very little juice. Actually, for all we know (and probably a good idea), when asleep your phone may be connecting over the lowest power radio available, which I assume would be Edge. And then ramp up to a higher powered radio when the phone wakes up.

    I am still trying to understand what causes the 3.5-4% drain per hour while sleeping that I am experiencing. I have all but eliminated background tasks as the culprit. Maybe it does have something to do with LTE. Right now I am leaning towards Location services though. My Surround has no SIM, and I have removed most third party apps that would try to connect periodically. But even with WiFi turned off, I was still eating through nearly a full charge every 16-18 hours. Turned off Location services, XBox connection and Zune Pass connection (I think that’s all) and the phone has been powered on for 4 days now, only dropping to 51% (as of this morning). Going to do more playing around to see what is draining that battery and then try to reproduce on the L900. Sure wish I had a dozen lab rats (WPs) so I could eliminate the variables more quickly. But I am a persistent SOB. So I will figure it all out. That you can count on.

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