New LED lighting for half the price

   / New LED lighting for half the price #31  
If I am doing this right, will handle 240 watts of 12 volt light.

Right now, I'm more concerned with the amperage draw on my system. I had a 55 watt work light that I think was drawing too much juice. So, I wanted to go LED because I understood their draw is much less than regular lights. Is the "27 watt" rating on a LED general equal in draw to a "27 watt" regular light? Do the LED sellers base their wattage ratings more on the light output than on the actual draw?
 
   / New LED lighting for half the price #32  
The 27 watt refers to the power consumption. 27w means it draws UP TO a couple amps when producing light. The lumens is amount of light the lamp produces... You will find that these LED lamps draw less than 2 amps each at 13.5 volts, which is approximately the voltage coming from your alternator when the engine is running..
 
   / New LED lighting for half the price #33  
DC is hard on switches, contacts, etc. A switch that is rated for 20 amps AC is not the same as one that is rated for 20 amps DC. AC switches polarity 60 times a second, and when you open up the switch, there is little or no arcing. DC, on the other hand, is extremly destructive, especially on inductive loads [ coils, relays, motors, etc. ] When the switch is closed a surge of current energizes a coil on ... say a relay... Once the relay armature is pulled in, not much current is required to keep the relay energized. When you open the switch to shut the relay off, the collapsing magnetic field of the relay causes a reverse pulse of DC current as the switch opens. This reverse pulse wants to cross over to the other side of the switch as you open it.... and takes copper with it as it struggles to keep crossing as the switch contacts open... :)
 
   / New LED lighting for half the price #34  
....When you open the switch to shut the relay off, the collapsing magnetic field of the relay causes a reverse pulse of DC current as the switch opens. This reverse pulse wants to cross over to the other side of the switch as you open it.... and takes copper with it as it struggles to keep crossing as the switch contacts open.. :)

An appropriately sized capacitor across the leads will absorb this pulse and significantly lengthen the life of the switch.
 
   / New LED lighting for half the price #35  
You can put a diode backwards across it, too. That is how most electronic stuff is protected. A lot of automotive relays come with the diode installed internally to the relay these days with the computerized stuff in the vehicle. The LEDs are probably a resistive load, which is not near as bad as an inductive... Still have all those holes zooming around going from postive to negative .,.. and them electrons trying to fill the holes going from negative to positive... [ that's what they were teaching in night school back in the 60's, anywhilst ] They don't like being interrupted in their quest either... The cap works for both the resistive and inductive... and if you put a big 'nuff one in... you can have a fancy OFF DELAY circuit.. :)
 
   / New LED lighting for half the price #37  
If you notice, the lamps are good to up to about 30 volts. The lamps are made up of a bunch of 3 watt LED units, the 27 watt ones have 9 of these for 27 watts. [ the 36 watt lamps have 12 LEDs, etc... ]. What they are saying is that the total maximum current draw is 27 watts. I don't know how the circuits are designed, so I don't know if the light output is regulated for any reason. I have 4 of the 27 watts lamps on my tractor, and I measured about 1.5 amp current draw on my Fluke meter... thought it might be wrong, got another meter out, and it was still about 1.5 amp. So, don't worry, be happy..!!!! They sure put out a lot of light.... :)
 
   / New LED lighting for half the price #38  
Just to confirm; this is 1.5 amps each light? Not, 1.5 amps total for the four lights.
 
   / New LED lighting for half the price #39  
Just to confirm; this is 1.5 amps each light? Not, 1.5 amps total for the four lights.

Sorry, 1.5 amps @ 13.5v [ engine running charge voltage ] per lamp... That's about 6 amps for the four...
 
   / New LED lighting for half the price #40  
Sorry, 1.5 amps @ 13.5v [ engine running charge voltage ] per lamp... That's about 6 amps for the four...

That's what I thought, just wanted to make sure.

Thanks to JerryK and everyone else for all your help and information with this project.
 
 
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