really it works, really! It allow the battery circuitry to calibrate to the right energy level.
After flash a ROM, I let the battery completly discharging and then I charge my device for minimum 8 hours. then on 30% battery level I repeat this process. my battery has 40 - 50% longer life with the same usage.
"Even though lithium batteries don't have the memory effect issue, they still have a phenomenon called state-of-charge (SOC) mismatch. Battery Discharger employs various hardware resources available on the phone to discharge the battery power at a faster but controlled rate. Charging the phone completely from this state would allow the microprocessors on the battery circuitry to recalibrate and start reporting accurate energy levels.
Battery Discharger is a smart app that lets you discharge the battery of your phone at various discharge rates in a controlled manner. User can configure Battery Discharger app to use one or more of the following hardware resources to achieve the optimum discharge rate"