Thanks for being with Samsung and for sharing your concern. During wireless charging or fast charging, the device may feel hotter and this is normal range of operation which does not affect the device’s lifespan/ performance. If the battery temperature goes beyond specified limit, the charger may stop charging the device and start charging again once temperature goes down up to the normal temperature (e.g. 36ºC) and this is only a precautionary action for customer safety. This mode is called as “Swelling Prevention Mode”. We would recommend taking some troubleshooting steps to further isolate what you may be experiencing. Find troubleshooting steps on provided link http://www.samsung.com/in/support/skp/faq/1101689. Please let the community knows what steps you has taken and if you have noticed any changes or improvements. This will help the Community to provide you steps without repeating any steps you may have already taken.
