Note: This is done using a the motorola milestone 1. So if you're using any other phone, pls ask abt them in this thread b4 you do anything!!!!
The calibration of the battery is needed when you want to switch/install roms. This will make sure that the battery is really fully charged, thus preventing the battery life from dropping too drastically in a matter of hours.
I know there are some other methods to help calibrate your battery, but this is the only one I am sure of the steps. Please inform me of the other methods so to share with everybody.
1. Before flashing a new rom, use root explorer (with read/write set) to delete the file "batterystats.bin" stored in /data/system/.
2. Charge your phone with it being turned off.
3. After it is fully charged(100%), take out its battery without plugging off the power supply.
4. Wait for a few moments, and a ? sign will appear.
5. Put your battery back in. You should see that the battery percentage increases quickly to 60%. If it increases to 100% with seconds, please skip to step 6.
6. If it stops increasing at 60%, let the phone continue to charge until 100%(takes quite a while)
7. Once it reaches 100%, let it charge for a further 15-20 minutes.
8. Once that's done, you can boot to OpenRecovery and flash your rom!!!
Alternative way of calibration(thanks a lot zeppelinrox!!!):
This method allows you to calibrate the battery and use ur phone at the same time!!!
I hope this helps you people, because it really helped me!!!!
Note: i m not responsible for anything bad that happens to ur phone. Perform the calibration at ur own risk!!!(though it should be perfectly fine, unless u do something wrong or extra)
Btw, i am just writing things that i assume to be correct, so if anything needs to be edited/added, pls inform me through this thread or sending me a pm.
Credits to everyone (especially pcphobic for his post in http://forum.xda-developers.com/show...&postcount=740) who have written all these in your posts that made it possible for me to gather and get all this info!!!!!!