Hi Everyone Here is the system I have made for my 4500. It uses a 5000mah Lipo battery from A RC car. Runs the 4500 for about 5 hours. Have two. Use one for a spare. I use a Amp of my own design so no more power supply hum. Everything weight about 10 ozs. Charger runs off 12v or 110v. Taks about 3 hours to charge. Can be set up to run a SD or GP with a voltage controler in the amp box. Only one wire to the headset. Ken