Hi Dave, Wayne told me not to exceed the published DC Voltage...14VDC... i may have gone above that a few times... i have modified my KX1 to use 1/2 AA NiCad batteries and have an external recharging socket on the side. i use 10 1/2 AA's and 1 regular AA NiCad. i can adjust the maximum voltage by mixing 1/2 AA's and regular AA's. Paul w0rw