Hi, as my colleague Ondrej said, apps cannot control battery charging speed in any way. Only the device itself can control charging process, controlling voltage, temperature etc.
Li-ion batteries works in way, that 80% is quickly charged, and rest 20% is charged slowly.
Only thing that Battery Doctor is doing here is showing nice animation.
We don't want to make such useless features in our app, we focus on things that really save battery.
Try our app for few days, that competitor app for few days and you will see the difference.