Doesn't do anything
1. Lithium iOn batteries does NOT overcharge at all. Not sure why this app has this. When lithium ion battery is fully charged, charging stops and remains on A/C until it detects that the battery has lost some of it's charge. Only then will it start to charge it full again (Trickle charge). It would be great if the dev removes or change the stats for the "Overcharge" as there is no such thing for lithium ion based batteries. 2. IMO. I don't believe any battery apps fixes or improves battery life at all. The thing with this is that you have to keep the app running (in the background) to record the charge, thus makes your battery warm and therefore can make your battery life worse then it gets better. 3. If you have battery issues such that it doesn't hold a charge or it doesn't go for long, then consider taking it to the Genius Bar at the apple store and consider having them check it and see what they can do. They will likely to replace it. Or you can simply go online and buy a replacement battery and fix it yourself.