So this is the wiring harness I got my with my D2's originally. My question is can I run five D2's wired in parallel without any other changes or would series be better?

 

How many watts do each draw? I know that I had two 130w pro comps wired to one relay. Just run all your wires back to the relay you should be fine.

 

Dually's draw 15W and the D2's draw 28W.

 

Divide ( watts/volts=amps)
Check your relay amperage.
So, 15/12=1.25 watts.
If your relay is a 30 amp and your wire will handle the amperage.
You should be fine.
30 amp relay/ 1.25 amp per pair= a crap ton of lights

 

"cajun01" is on the right track. Most lighting manufacturers only design their harnesses to power only one set of lights. But, since LED's have such low current draw. The manufacturers harness may be capable of handling more lights. But you will have to do some research to determine if the harness is capable of handling the additional load. So, first step would be to determine the wire size of the manufactures harness. The power wire may be different from the actual lighting conductors. So you may have to look at the wiring on both sides of the relay. So, as long as the connected load doesn't exceed the limitations of the wiring. And the relay and fuse quoridnate with the load. Then - you should be fine.

 

It's a 60amp relay and the wiring says this, "E96118 AWM STYLE 1015 18AWG 105*C 600V FT1 -F- -LF- CABLEPLUS"

so with about 9A total being drawn by the 5 lights, I should be in the clear, right?

 

There is a safety factor on a relay. I don't remember the exact number.
IMO, you should be ok.
Hopefully, a couple other guys will confirm my thoughts

 

Should be good to go.

 

Ive been considering doing this as well, but havent really had the balls to cut the wire on my rigids lol. Could you do a 10' light bar and a pair of duallys?

 

I run 4 duallys out the back all through one wiring harness I just soldered the sires together and they've been fine for months. I probably wouldn't do 5 D2's though since they do eat up more wattage. I'd say run thicker wires or two sets to a relay then to one switch.