[G2 Q&A, Help & Troubleshooting] jonstrong:
Answer to: "Why, after great battery life, did my battery life deteriorate?"

This isn't a question -- but I think it's the answer a question that I have had, and that I suspect others may have had as well. To formalize this, the question could be:

Why, after having had great battery life for 3 months, did my battery life drop down dramatically, and stay there?

I've had my G2 since Cyber Monday, and it's been a spectacular phone in general, and like so many others, I've experienced fantastic battery life - until a couple of weeks ago. Instead of 40 or 50 hours, and 5 or 6 hours of screen time, I watched my battery running down to 40% by midday, and when the battery was at 15% before bedtime, I only had gotten less than 3 hours of screen time.

I examined all the running processes, ran various utilities like better battery stats, experimented with the GPS, location services, etc -- although that shouldn't have been necessary, since I had no problem with any of those until the past couple of weeks. Google services were consuming most of the battery, and producing a lot of wake locks.

While digging through files and processes, trying to find a clue, I was reviewing my accounts, finding and removing duplicates, and I noticed that I was having sync issues, specifically seeing the message:

Sync is currently experiencing problems, it will be back shortly

Lots of posts on the topic with various suggestions - and one in particular caught my eye. It seems that, although my phone appeared to be acting normally for the most part -- allowing me to send and receive email, add events to my calendar, etc. But I was still seeing that sync error message. Seemed a bit contradictory, but it seemed as if the gmail and calendar client had remained logged in, despite my having changed my account logon password awhile back. I don't know the innards of Android account management, but my impression is that sync services log on periodically -- and couldn't at that point. Guessing this was the cause of the error message (sync experiencing problems). I tried to "add an account" / "existing account", but couldn't add my Google account while it was already in place -- so I removed the account re-added it -- this time specifying the new password I had established earlier...and syncing started to work. It took some time to sync gmail, calendar, docs, etc -- but it all worked this time with no error.

In several hours since that time, with the phone idling, interrupted by just a few minutes of use, the battery level has only dropped 1%. Screen has consumed 42% of the battery, Android System and OS less than 15% each. Too early to be sure, but this already looks a LOT more like what I had been experiencing when battery life was great.

My guess: the Android sync service was unable to log in, and kept attempting to very frequently -- hence the wake locks, and excessing system activity that actually used more battery than any other process. Once the proper credentials were known again to the sync service, it started working normally -- and allowed deep sleep once again in between sync events. Again -- I don't know the innards, so there's some speculation here, but it seems reasonable - and the results are very promising so far.

Any of you seeing less than the stellar battery performance the G2 *should* be enjoying might want to take a look at Settings / Accounts -- and then take a look at your Google account -- display the list of accounts and then tap on the Google account itself to see Data & Synchronization. Depending on what you have installed, you'll see items like App Data, Blogger, Calendar, Contacts, Drive, Gmail, etc. From here, you should be able to see if they're all syncing properly - or not. If you're seeing the message, like I did:

Sync is currently experiencing problems, it will be back shortly

You might want to try working your way through the solution I describe above.