Battery drains while WiFi is on

Kindle Fire HD might have an issue with the battery while not in use. I can not fail on this repair,this happens to be my most important client, my wife. My first initial analysis leads me to believe the over charging control needs to be updated on the devices.The problem reported to me is the battery loses almost 30% while not in use unless the WIFI is turned off before logging off.Is this an over charging issue or a broadband signal glitch? Of course i will report to my client that this is not human error that IFIXIT is helping me correct this issue as we speak. If you can relate to this experience please send your findings ASAP. BE the Hero my Wife believe i am and send me the ifixit repair process. thanks for reading.