iPhone 4 6.1.2 battery drain overnight and fast in general use

I got the same problem as well, i did tried to turn off location service and it actually helped a bit~

I had this after updating to 6.1.2 - and the phone was getting extremely hot too - two 10 mile round trips to the Apple Genius Bar and although still under warrenty, I had to demand my phone was replaced. They advised it was a software problem and that their software that they would install on my phone would solve it...it didn't. However, I was then advised on my second visit that this was because they backed-up my phone to my back-up which had the "glitch" installed in it!! Frustrated was not the word, therefore I requested phone was replaced as I was not going to "try" any more of their ideas. I'm not updating my new phone to the 6.1.2 as this new one is working perfectly.

Look to "More Like This " column on right to discover LOTS of others experiencing the same high level battery drain along with proposed solutions which have worked for some. The battery drain, which was supposedly caused by Exchange/Calendar issue, was to be fixed by iOS 6.1.2 , but I--like many others--didn't have a problem prior to installing it. I've tried all recommended fixes (remove/reinstall e-mail accounts, toggle calendar off/on, turn off location services, bluetooth, reset as new phone and downloaded apps bit-by-bit from the web (not back-up). I've also made two visits to the Genius Bar AND am working with my company's IT department. (The Exchange issues cited by Apple are NOT an issue within my company.)

My phone is unusable as a 'smart phone' as I've disabled so many features and reset almost everything. Apple offered to replace/upgrade the phone, but with no guarantees that the problem would not remain. (The 'geniuses' know this is a software glitch!). I've opted for an Android replacement from my company until Apple resolves the issue. I've invested far too much time and frustration these past few weeks, and at this point it seems easier to rely on Apple to fix than to continue fruitless efforts. The real puzzle in all this is why it is affecting some and not ALL 6.1.2 users. In addition to visiting the Genius Bar, I've formally reported the problem in writing/e-mail to Apple Support, and would urge everyone experiencing difficulties to do likewise.

A good article summarizing the issue and magnitude of such: http://www.gottabemobile.com/2013/03/08/ios-6-1-2-bugs/

Good Luck.....and remember that patience is sometimes as important as persistance!