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I'm a bit ignorant about LED lights so let me ask a rookie question.
Does OHM'S law apply to LED lighting?
All manufacturers give specs as watts so theoretically speaking using OHM's law a 120 watt light bar would pull about 10 amps is that correct?
Also how many amps does a stock RZR S alternator put out?
I remember back in the day I had 4 off road lights on my Toyota pick up and while running them all I could drain my battery faster than the alternator could supply power.
Now I'm running 3 HID lights on the light bar and HID headlights would I most likely be saving power running a larger 180 watt 30" LED light bar?
 

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Yes, ohms law applies to every electrical device circuit you will ever come in to contact with unless you are into quantum physics and that stuff. Remember your voltage various from 14.7 to below 12 depending on your rpm and load on the stator. Ohms law will get you in the ballpark for your light bar but it might draw more or less power then the average "spec" model. Don't forget start up amperage is different then running amperage. LEDs are diodes, one way valves that produce light as a byproduct. They will have very little start up amperage creep compared to let's say your HID ballasts that start out with consuming up to 80 watts of power to ignite the bulb before switching to the lower output and waveform. Anyways what size HID ballasts do you use?

120w LED bar
120 watt / 12.6 volt = 9.5 amps
120 watt / 14.7 volts = 8.1 amps

HID ballasts
35 watt / 12.6 volts = 2.78 amps
35 watt / 14.7 volts = 2.38 amps
50 watt / 12.6 volts = 3.96 amps
50 watt / 14.7 volts = 3.4 amps
 

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So what do they charge at?
Can you run a light bar off the stock setup with no mods?


Sent from my SCH-I605 using RZRForums.net mobile app
 

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What if I buy a 300Watt light bar? how many amps does this drawl? Is there a easy way to figure this out or should I stick to 180w to assume it drawls less amps??? most sites don't list the amps
 

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300watt/12volts=25 amps, 300watt/14volts=21 amps
Power(Watts) is your amp draw multiplied by your voltage. Anytime you want to know Amp draw and you have your Power(watts) just divide it by the voltage you will be running.
 

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Just remember PIE. Power(watts)=amps x volts. Ohms law. Always error on the low voltage side and use the correct wire size for the run.
 

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Very simple as stated in this thread. watts divided by voltage = amps. IE 120 watts divided by 12 volts = 10 amps. you can use this as a good reference for switching and if you need a relay.
 

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However---Many of the LED light bars from China (for example, on eBay) have specifications that are HIGHLY over-rated. They know you and I would probably choose the 2000 watt light over the 500 watt light bar. So I just looked and found a bunch of 2880 watt LED bars. If that is the truth, 2880 watts / 12 volts = 240 amps! That is not realistic. If it was accurate, we'd need a 3/0 wire (0.4 inch diameter conductor!) for a ten foot run!
 
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