delta q powerwise qe charger

[fm544]

I converted my 94 medalist to 48 volts and bought a 48 volt powerwise qe charger.It has 3 wires/prongs in the plug and the old 36 volt only had 2 .does anyone know where the third wire goes or does anyone have a wiring schematic for a new 48 volt rxv charging receptical to batteries?thanks for any help