I must admit, I have been thinking about using these, but haven't yet. I do check the voltage before I fly, and between each flight without fail. I even check it before leaving the house for the field. I have a 4*60 that was saved from certain death by doing this. I left the house with 5.2 volts, go to the field, checked it again 5.1 volts, did my range check and sat and bs'd for about a half hour. Before flying I decided to check again and oops....3.1 volts. Bad battery. Still this device would make it more convenient, so maybe I really should start using them.