Well, most wall chargers will take upwards of 12 hours plus to fully charge a TX/RX. So, I guess it's self explanatory as to why you would need a fast/field charger. I gave 56 dollars for my hanger 9 double vision, and it will peak charge my TX and RX at the same time, in about 5-15 minutes, depending upon how drained they are. This way, you could literally fly all day long. However, I do believe my fuel bill has skyrocketed since my little investment....