To 'share' power in the field etc....
The 'ARRL' standard power plug:

Source End! Should be fused in positive lead receptacle with female pins is connected to the power source (battery, power supply, cigarette lighter plug) The triangular end of the connector is the positive end CRIMP & SOLDER
Load End! The triangular end of the connector is the positive end CRIMP & SOLDER
Package - Radio Shack # 274-222