I was very happy to see that the Jelly Bean upgrade was available for the T-Mobile branded HTC One S smartphone. I promptly downloaded and installed. Little did I know I would be having battery drainage issues.

A few days later, when I lost very important calls due to the lack of battery, I decided to ask for a replacement phone. This was after I read mixed reviews which made me think that I somehow had a faulty device (I read somewhere else that the upgrade should be performed with a battery almost fully charged to avoid a “memory effect” from the new OS – haven’t proved that it’s true though).

I opened a support ticket, and fortunately some folks have found certain work-arounds to reduce the battery usage. The same ticket was featured on the TMONews blog.

There is no official fix, however this is how I managed to reduce the power utilization (thanks to several folks that contributed):

1. Completely Disable Wi-Fi calling.
2. Disable Google Now, updates and cards.
3. Disable Google now location report.
4. Reboot your phone.

You can optionally tailor the background sync of your applications to reduce battery usage. For example, I allow automatic sync for Gmail, contacts, calendar and tasks. The rest is disabled.

It’s disappointing that Wi-Fi calling needs to be disabled as it was working flawlessly on this version; allowing me to go around the house and not losing a call.

HTC One S Battery Usage after the work-around

Someone else has suggested a workaround that avoids turning off Wi-Fi calling. I have not confirmed a power saving effect yet though:

1. Disconnect your phone from Wi-Fi (mobile network only).
2. Go to Settings > More (under Wireless & Networks header) > Usage…
3. Make sure “limit mobile data usage” is checked (set the data limit to whatever you’d like), and “show wi-fi usage,” as well.
4. You will find IPService and IMS Service in the list of apps/processes using Wifi data.
5. Open each process and enable “restrict background data” on both of them.
6. Since Wi-Fi calling is by definition is on Wi-Fi, these processes don’t need background (mobile) data. The user hasn’t had any problems making calls or checking voicemail with Wi-Fi calling so far.

I expect T-Mobile/HTC addressing these issues and work on a patch to reduce power consumption. Funny this update was being beta tested since December of 2012.

Update: Seems that T-Mobile has acknowledged the problem, and is working towards obtaining a resolution:

@jesseswang We are aware and are working towards a resolution. ^AC

— T-Mobile USA (@TMobileHelp) May 7, 2013

Battery Usage right after the upgrade: