Hmmm.. i should post a guide on all the stuff I found out... here is some of the most useful
Buying cheap: Save money... but do you?
A charger can have an adverse effect. Often, cheap chargers won’t respond so well to the shutoff mechanism in the phone.
Every cheap charger I tested allowed energy to come through in sporadic bursts, which isn’t good for your battery’s life. For example I bought a $2 micro USB charger and testing the pull inside my device ranged from 500 to 1200 mAh. The official Samsung cable allowed 1000-1200 mAh to be pulled. They both charged in similar times, (1 1/5 hours and 2 hours) however I instantly threw the cheaper USB cable in the bin. The battery should handle this ok... SHOULD.... but the cut off circuit inside your device may not function correctly, which would be tragic!
Test this yourself. Plug your phone into your charger and then into the auxiliary input in your stereo. If the audio becomes fuzzy and distorted, then you can be pretty sure that your phone’s battery might not be enjoying whats happening. Swap that power source out for one with proper insulation, and the audio should be crystal clear.
Calibrate your phone’s battery level indicator about once per month. You can do this by running your device until it dies... (0% battery)
The leave it alone for five hours, before fully charging it. This will enable your device to report the battery correctly.