LED light bar

[jelfert]

I plan On installing a 30 inch 180w led light bar. Voltage input is
9-48 volts. I've installed these light bars on atvs before and they require a 12 volt relay and switch for a 12 volt system. For the 24v system On my deuce I'm assuming a 24 volt relay and switch (napa sells them) will do the trick? Anyone done this mod yet? These lights always come with a 12v harness so I may have to make my own if a 24v isn't offered. The smaller led lights (like a 4 or 6 bulb) don't require a relay.

 

[gimpyrobb]

A 180w system will only draw 7.5 amps. I'm not sure a relay would be needed for that.

Edit, the 12v harness would be fine, you just need to use a 24v specific relay, not 12v, if you decide to use a relay.

 

[dmetalmiki]

I have code3 mx7000 light bars on my trucks. the wrecker which has "all options" draws 180w. (at 15a Max,) though I only use the "front and side options" (obviously) in my application. A very usefull guide can be found here. I do not use relays, One switch for each function as required. and current used to come from one battery. though I plane to install an accessory high power cell battery for next season.
http://www.sirennet.com/pdf/MX7000_install.pdf

 

[dmetalmiki]

Light bar and warning rotators.

Hope these pictures are clear enough.

 

[jelfert]

Nice looking trucks! Well i found a Niehoff dual voltage alternator (new) on ebay for $300. That should solve my 12 volt issues

 

[doghead]

From what you posted, I don't see why you need anything different.

Just wire it with a switch.

 

[RedBlok]

KC highlites sells 24 volt relays. They are out there you just have to dig. I plan to light bars next year.

 

[59apache]

no need to change the harness. 12V usually use thicker wires due the higher amperage.

 

[patracy]

I've got some spare 24v relays that plug in place of a standard automotive 12v relay if anyone needs one. Just pay to have it shipped. They're left overs from my MK48 cab.

 

[welldigger]

Nice looking trucks! Well i found a Niehoff dual voltage alternator (new) on ebay for $300. That should solve my 12 volt issues

Don't wire your lightbar 12v. They run cooler and more efficiently on 24v. As far as your harness and relay. Use all of it. Just wire it like you would on 12v.

 

[jelfert]

ok didnt think about it running cooler on 24 volt. I'll use a 24 volt relay since they reccomend a relay for this size light. The last one i installed on my ranger came with a relay in the wiring harness.

 

[59apache]

Don't wire your lightbar 12v. They run cooler and more efficiently on 24v. As far as your harness and relay. Use all of it. Just wire it like you would on 12v.

less amperage on the same wire or internal circuit runs a bit cooler (assuming the circuit / wire has the correct dimension for the lower voltage), that makes sense to me. But 180W are allways the same. The LED should make the same heat.
Don't want to be a smartass or offense, just want to learn. Why do they run cooler and more efficiently on 24v?

 

[gimpyrobb]

180w is 180w. If you run it on a higher voltage, they pull less amps. 24v= 7.5a and 12v= 15a. I'm not sure the led would be cooler, but the wire feeding them would be.

 

[59apache]

just what i mean. But i don't be familar with LED. maybe the build- in constant current modul warms les up. There must be one in, cause LEDs have very limited tolerance against current fluctuation.

 

[Hainebd]

Still need 24volt relay. The coil that pulls contacts in needs to be 24 volt. Be sure that the LED is good for 24 volt. Some are not and the will fail as quickly as a 12 volt relay with 24 volts wired to coil. Also make sure contacts are rated for voltage and amperage. Switches too.

 

[doghead]

At less than 10 amps, you do not need a relay. 20 amp switches are readily available, cheap.

 

[Hainebd]

You are right relay not needed for his light bar. I looked at the one posted and that one would be 12 volts

 

[welldigger]

less amperage on the same wire or internal circuit runs a bit cooler (assuming the circuit / wire has the correct dimension for the lower voltage), that makes sense to me. But 180W are allways the same. The LED should make the same heat.
Don't want to be a smartass or offense, just want to learn. Why do they run cooler and more efficiently on 24v?

I guess I should have elaborated a bit more. The led drivers and led's themselves operate on a fixed voltage and current regardless of imput voltage.

The lightbar itself may not run much cooler but running on 24v is less of an amp draw than 12v. So by running the lightbar on 24v it will be less taxing on your existing 24v system than it would be on a seperate 12v system. This would allow you to run more systems on the 12v circuit.

Led circuits can make your head spin when you really start digging into them. One common myth with leds is that they run cooler than other forms of lighting. This couldn't be further from the truth. While leds emit almost no infrared light the led diode itself and in some cases the drivers emit immense amounts of heat. Thats why the entire aluminum housing of many offroad lightbars are one giant heat sink.

On a related note I'm starting to believe this is why Trucklite led headlights and turn signals fail so often. They have no heat sink in them. Nothing. Add this to the fact that most led circuits are wired in series means the failure of one led causes a failure of that entire circuit.

 

[gimpyrobb]

Welldigger, I have seen one LED go out in the headlights and the rest work. I dunno about those being run in series.

 

[welldigger]

They may not be. And I could be very wrong as to why they fail. As we have discussed before my autopsy of a trucklite led fixture wasn't nearly as enlightening as I had hoped. But I can tell you I saw no provision for heat dissipation. This can cause a spike in forward voltage and fry the diode. I'm honestly mystified as to why they are constructed the way they are.