Quick electrical question

[bikerjosh]

I currently have two of the 35 watt HID (Kragen style-red outer ring) lights on my roof rack. Could I run 4 35 watt HIDs through the same 30 AMP relay? I'd like to splice the other to lights into the same wires going roof so I don't need to run anymore through the headliner. Does that make sense; haven't had any coffee yet and my 10 month old has a cold so sleep deprevation is making me a zombie.:gun4:
thanks

 

[nissanh]

Equation to calculate the amps is W = VxI. W = watts, V = volts and I = amps. With a 30 amp relay you can take out W = 12 X 30 = 360 watts of power. If you are using a regular cubic relay (non OEM denso), I recommend, do not run max amps. With two 100 W halogen lamps, a 30 A relay (non OEM) got roasted!

Same here with my daughter!

 

[mikebontoft]

you can calculate max amperage draw by taking the total wattage (so, if you mean 4 total 35w lights, you will have 140w draw) and dividing it by the lowest voltage your battery will see. (the lower the voltage, the higher the draw). in this case I used 12v.

140w/12v=11.6 amps. so, yes. it's fine. wire in series-parallel. you have one big wire for all four providing power, and then tap into it for each light.

 

[Socco]

you can calculate max amperage draw by taking the total wattage (so, if you mean 4 total 35w lights, you will have 140w draw) and dividing it by the lowest voltage your battery will see. (the lower the voltage, the higher the draw). in this case I used 12v.

140w/12v=11.6 amps. so, yes. it's fine. wire in series-parallel. you have one big wire for all four providing power, and then tap into it for each light.

X2. I run 3) 100W Halogens off a single 30A Bosch relay with no issues.

 

[mikebontoft]

^^that is cutting it close though... about a 25a max draw.

 

[zooroadbaja]

Don't HIDs pull more though when they are first fired?

 

[Socco]

^^that is cutting it close though... about a 25a max draw.

Yeah, the Bosch relay will run 30A all day but I just scabbed it in to make a trip in time.... 5 months ago... Got a switch from OTRATTW sitting on the bench and a 40A relay just for peace of mind. Just need the time to get her done.