The lights are not universal with the Explorers.
When I wired sets of them for friends of mine, I just wired them straight to a switch. I ran a fused power wire straight from the battery to the switch. Then I ran the positive wires from the LEDs to the switch, and grounded the negative wires.
The LED's only draw about 0.1 amps, so a relay is probably not necessary. But be sure to fuse the power line to the battery. A 2.5 amp fuse will do fine. If any of the power wires ever chafe and short, 2.5 amp fuses blow really easily.