briandye Posted July 15, 2015 Report Share Posted July 15, 2015 I already did an LED swap, which seems to be about the same output, just crisp white. I have these small 4" 18w bulbs that I would like to add, possibly under the bumper or somewhere you can't see them, to really light up the ground since I do a lot of reversing at night (that sounds weird, lol) Could the circuit handle 18w bulbs on each side? (I doubt they're actually a true 18w, the wire going to the housing is smaller than the Edge reverse lights socket, so I would assume it should be okay? Picked these up for $18 for a cooler radio/wagon build I'm doing and had this idea since they're still sitting around. Quote Link to comment Share on other sites More sharing options...
WWWPerfA_ZN0W Posted July 15, 2015 Report Share Posted July 15, 2015 18 watts would be fine. Specs for sample 921 bulb Quote Link to comment Share on other sites More sharing options...
Tacyon Posted July 15, 2015 Report Share Posted July 15, 2015 (edited) For today's class .. you're going to look at power equations. Please turn to page 17 in your books please. The current I in amps (A) is equal to the power P in watts (W) divided by the voltage V in volts (V) We want to know "AMPS" as this is the killer of fuses and wiring if not fused. We know the power in "watts" and the voltage (~12VDC aka 12 volts direct current) and since most the fuses in automotive applications are in the 5-20 amp range, this calculation comes out to ~1.5 amps for a 18 watt load operating in a 12VDC circuit so we are fine. TL:DR - Yes. What he ^ said. Edited July 15, 2015 by Tacyon Quote Link to comment Share on other sites More sharing options...
akirby Posted July 15, 2015 Report Share Posted July 15, 2015 Except you forgot to account for the existing LED bulbs because he's adding these, not replacing the existing ones. And there are two of them on the same circuit plus the LEDs. LEDs draw little current so I'm sure it's fine. Quote Link to comment Share on other sites More sharing options...
Tacyon Posted July 15, 2015 Report Share Posted July 15, 2015 So .. please turn with me to page 18 in your books ... but seriously .. I didn't "forget". I just didn't feel a need to account for roughly 0.003 amps times "X" number of existing LEDs in a circuit built to handle far more than that. But for accuracy sake .. you're correct as well. "LEDs draw little current so I'm sure it's fine" Quote Link to comment Share on other sites More sharing options...
akirby Posted July 15, 2015 Report Share Posted July 15, 2015 Sorry, I'm a stickler for details. Quote Link to comment Share on other sites More sharing options...
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