Excessive Heating of battery is a typical, inescapable effect of using " fast or rapid " chargers. Reason behind this is the charging rate. Normal charging uses 0.5 to 0.8 C (C is the charge rate) whereas fast charging uses anything between 1 to 3C. In simple words, this is pushing more current to charge faster. Heat produced is related to Power and governed by the equation
Power = I² * R where I is current.
So increase in current has a significant effect on increase in power (being proportional to square of current) , therefore heating, and the same is being reported by your app
Yes, it does have adverse effects:
- In Short term: meaning when you charge and use, the Battery delivers less performance (another way of putting it is what charges faster Will also drain faster)
- Long Term the battery life is reduced
Refer to my answer here for detailed technical explanation and a graph showing adverse effects How does fast charger work?
Edit: A helpful note on heat increase while charging from All about Battery Chargers
Li-ion should not rise more than 10ºC (18ºF) above ambient when reaching full charge.