[HTC One X] PhilipL:
Hi

Some have good battery life, others say it drains away by itself in a matter of hours. I've been experiencing a several percent battery drain an hour when the phone is just idle so did some digging.

Exchange Active Sync on push

Exchange Active Sync on push can go from being very efficient, i.e more so than frequent polling, to being a big battery drain.

Because of the way EAS works on push, the phone is woken every 15 minutes to check and renew the link to the server. If the network or service provider has a low time-out on idle connections, say 5 minutes, the phone eventually works out it needs to wake and renew the link every 5 minutes. If the network time-out is very low say a minute, the phone is being woken 60 times an hour to renew the link. Because the wake cycle is very quick, it doesn't show in the battery chart as a blue line wake event, so this awakening is hidden, however all that waking up takes it toll on the battery, plus the radio has to go from low power states up to full to pass data and open a new link, so over the course of a day, EAS can be using a significant amount of power.

Also as this wake cycle is dynamic based on the network it is going to vary for everyone, and any configuration changes unknown to us on the network could suddenly see the phone battery life making a big improvement or getting worse and no two people will have the same experience of EAS on push.

If you find the phone is losing several percent an hour even when sat being unused, and you are using EAS on push, try disabling it or moving to a timed polled. If you just have to get your emails immediately, you may just have to take the hit.

HTC Weather Widgets

I think I have found an odd thing about HTC Weather Widgets, they are not all the same when we are asking them to show our current location. Some HTC weather widgets use HTC's own server to decide the current location based on the cell tower, other HTC weather widgets use Google Maps API to fetch the current location. When using Google Maps, it uses more CPU power, and means Google Maps is activated quite often by some weather widgets where it then starts using Wi-Fi and often GPS (it uses GPS to get a good location then sends that location back to Google's servers with a list of nearby Wi-Fi points to build its Wi-Fi location database). If you see Maps using several percent in the battery usage list along with some GPS seconds and you haven't actually used the Maps application, this is probably the reason.

The easiest way to tell which HTC Weather Widgets are using Google services and so draining more power is to go to Settings -> Location and disable Google location services. Now the widgets using the Google Maps API will show a message telling us to enable Google Location services, other HTC weather widgets carry on working showing the current location. I found the large full page weather widget, and the lock screen weather wallpaper carries on working showing the current location without needing Google Location, but the weather/clock widget, set by default on the home page, is using Google Location.

I've since set the weather clock to my fixed home location, keeping the lock screen weather and large weather widget on current location, and 12 hours in, even with Google location services enabled, Google Maps has yet to show up in the battery usage list at it's usual several percent, prior to this change, the Maps app, even though I've gone days without using it, has constantly shown in the battery usage list.

So since putting EAS onto manual, and setting the clock weather widget to a fixed location, my phone can sit happily for a couple of hours, still connected to the network for phone calls and texts and ready for me to pick up and use, but doesn't report losing any power. This means when I do want to use it, I have more power left for on-screen time.

There are probably many more innocent widgets or settings we can change that can cause a knock-on effect to battery life that we don't quite expect. It also means no two people, once they've played and customised the phone to their liking, will have the same experience with battery life.

I also suspect a big part of custom ROMs having better battery life is simply down to the often stripped away back to basics nature of them, by default HTC Sense is using a couple of percent an hour just on the clock/weather widget to show us our general current location. Over a day that adds up to a lot of power just to see on your phone what you can see looking out of the window.:confused:

Hope the above helps someone.

Regards

Phil