Calibrating your battery, in case of strange battery drain

After flashing your device multiple times you might notice, that the battery level of your device is droppng very fast. Also after you disconnect the device from the charger, your batterey level immidiatly drops 1-3%. This is because you didn’t charged your device to 100%, before you flashed the new ROM. Altought this might be impossible, because according to my experiences to battery isn’t charging while you’re in Recovery mode.

So you’ll have to recalibrate your battery:
First of download Terminal Emulator from the Android Market. Don’t worry, it’s free of charge. The terminal Emulator let’s you acces the Android systems built-in Linux command line. We will need this later on.
Second, you’ll have to fully deplete your battery. Turn on Wi-fi, Gps, change the sleep policy of the screen to never turn off, play games, etc. Once your device shuts down try to turn it on again, to check that the device is totally out of juice.
If it is, than connect it to the charger. Charge it until it is on 100%.
Now turn it on. After the phone boots up, you might notice that the battery level isn’t 100%, keep charging it until it is.
Now find the Terminal Emulator in the app drawer and launch it. You will see a basic command line, wich you might be familiar with. If not, then fear not, the upcoming stuff won’t be complicated.
The keyboard might not be visible, if not than hit the Settings button and tap “Toggle soft keyboard”.
Now the pesky keyboard will stop hiding, and come to our aid.
Type “Su” in the field, and hit Enter.
Now the application will ask for Superuser permissions and a window will pop-up asking for your approval. Allow it, then enter “rm /data/system/batterystats.bin” into the field and hit enter again.
This will delete the current battery config file, forcing the system to create a new one.
You won’t see any comformation text, that you in fact really deleted the battery config file, so enter “rm /data/system/batterystats.bin” again.
If you entered the text correctly for the first time, than the command line will inform you that such a file doesn’t exist.
Exit the application, and disconnect the device from the charger.

You’ll might have to do this for a couple of times, but it worked for me after the first try.
Before I used the method above, I had around 5% of battery drain in every hour. After using this method I have about 1-1,5% battery drain. 🙂
You can use JuicePlotter from the market, to monitor your battery consumption. It’s also free of charge.
[from Munszu]

My battery life

Previously I was on Darky’s v5, with that the phone lasted 2-3 days with normal usage.

After flashing to v7 (with 100% battery) I also got the fast drainage problem. Here is what I did:

1) Turn OFF phone
2) Charge till it says it is FULL
3) Start in RECOVERY (volume UP+Home+Power), here WIPE battery stats (it is in the “advanced” menu)
4) RESTART android (yes, it might already be on 98% or so)
5) USE phone heavily. Don’t worry if it drops too fast. Use it till the Android system turns OFF automatically (it happens when your battery is below 1% – for me the phone was on 1% for about 40 mins. This is where it heavily miscalculated
6) PLUG IN your charger, TURN ON android and wait till it is FULLY charged again. (It is better if you don’t use the phone at this charging up)

Now, after you disconnect the charger, you should still have 100% for some time (I’ve been using the phone for 32 mins – writing this post – and it is still on a hundred percent) and with this, I got back the 2-3 days battery life with normal usage.

Also, you should set WiFi to: “Never when plugged in” and by default I disable Data Network. But my phone is using WiFi all the time so it doesn’t really matter

So to summerize this method, the key is to show the phone the battery’s minimal capacity too, by using it till it is on null. Because with charging to 100% than wiping or flashing only introduces the maximum capacity to the system and the minimum is only guessed. THIS gives the faulty reportes and makes us think the phone drains too fast.

Try this method, than feel free to share your results.
(from xda user: TechnicR)