Led truck lights

[rdickinson]

I've mounted truck underbody lites to light the area under and close beside the truck and trailer. I'm one who drives at night and sometimes late at that. Anyway there are 6 under the truck and 8 under the trailer, 3 have failed under the truck. They are either 18 or 23 or 27 watts each, not sure. There are some 27 watt and 60 watt lites on EBay.

 

The question is how do you calculate the draw? Having said that, all my interior lites have been replaced with led's and strip lites which combined draw a lot less than the old incandescent and fluorescent bulbs and tubes.

 

My choice would be the 48 watt lites on EBay if there was not an appreciable increase in draw to cause load problems.

 

I know you multiply amps x volts to get watts, but is it the same for LED's??

 

Thanks

[Phil D]

I'm not familiar with the specific lights that you're dealing with, Roger, but for home lighting purposes, LED bulbs are typically rated/sold on a "wattage equivalent" basis, with the actual power consumption being a very small fraction (less than 20%, if I'm not mistaken) of what an equivalent incandescent bulb would consume. I would suspect that is what you're dealing with, because an LED bulb that actually drew 60 watts would be intensely bright, and not what you'd select for your present purpose.

[rdickinson]

http://www.ebay.com/itm/251903402269?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Here's the link to one site. There are lots at 27 watts. They are under the truck body to lightup down and slightly out. No neeed to light up a city block, just under the truck when jackknifing turning sharply into a spot at nite so the truck underbody doesn't clip or get hung up on whatever. These lites are tapped into the truck backup lite circuit.

 

The 8 trailer lites pull off the trailer batteries thru a relay. 2 on the front landing gear, 2 in front of the trailer wheels, 2 behind and 2 at the rear of the trailer lighting slightly out and down. No sense lighting up behind the trailer, can't see there anyway. Works pretty slick. One park manager said it looked like Hollywood had arrived. Thanks for the response, I want to get these ordered asap so they can be installed on my next build cycle.

[ICPete]

Hi Roger,

Those lights look like a great deal; about $16 each. If the quality is anything near what is described in broken English in the listing, they should be very sturdy and very bright for what you want.

It states each light has 16 LEDs inside, drawing 3W each; that is how they get the 48 W rating in the listing title. I'm not sure what the 27 W figure refers to. One possibility is that the optical output (actual luminous power) is 27 W. But light output is normally rated in lumens, not watts; but watts is a perfectly good unit to use. There is also a (slight) possibility they are underdriving the LEDs, so that the total power consumption is only 27 W, but I don't think that is as likely. Actually, now that I look at some of the other lights on Ebay, I suspect the 27 W figure is simply a typo in the ad!!

 

So the maximum power draw per light is 48 W, or about 4 amps given your 12 VDC system. Wiring of at least 16 AWG should be OK, but bigger (14 or 12 AWG) would be better. To give an example, say your light is 15 feet from the battery bank. Then the total wire length would be 30 feet (out and back). The resistance of 30 feet of 16 AWG copper wire is 0.12 ohm (using an online wire resistance calculator). The total drop would be 4 A x 0.12 ohm = 0.48 V, or about 4% of your battery voltage. That's probably acceptable, but not great. And that assumes running separate wire pairs for each lamp. Just for grins, the drop for that wire length using 14 AWG would be 0.30 V, and for 12 AWG it would be 0.19 V. I think most vehicle lighting is powered by 16 AWG wire and it's generally adequate; just try to keep the runs as short as possible.

 

The LEDs inside those lights are probably quite similar to the 3W to 5W LEDs inside many LED flashlights. So you can imagine how bright they will be having essentially 16 bright flashlights on at once. This is NOT accent lighting! These are intended as work lights to illuminate a good-size area where you are working at night. Since each LED has a forward voltage drop of about 3 volts, and the current must be controlled to a known value to keep the LED happy, they are probably connecting all 16 LEDs in series, and then using an efficient solid-state boost power supply to convert the vehicle voltage to the roughly 48 volts required to power the LEDs. Those constant current power supplies have become quite cheap due to the profusion of LED lighting now available. The power supply can accept a wide range of input voltage, as long as it doesn't come too close to the 48 V nominal output. Hence the stated input range of 10 to 30 VDC.

 

For what you are describing as your goal, I think I would go with lower-wattage similar lights. For instance, there is a "Cree" 18-watt light containing six 3-watt LEDs inside. That would only draw 1.5 amps per light. And they cost less, at 2 lights for $16.99. Perhaps buy a pair of those first, and try them to see how bright they are. Given the lower amp draw, the drop in my wire length example above would only be 0.18 V for 16-gauge wire. Heck, you could get away with 18 AWG, or wire two or three lights on one pair of 16 AWG wires.

 

Pete

[ICPete]

Roger,

BTW, were your old lights (that have failed) incandescent or LED?

Because if they were incandescent, you'll need a heck of a lot less power draw with LED lights. As Phil stated above, typically you can figure on 1/5 to 1/6 the wattage for the same amount of light output, when switching from incandescent to LED.

So if you're replacing a 27-watt incandescent lamp, you only need around 5 watts of LED lighting. One or two 3-watt LEDs would be enough.

Pete

[rdickinson]

The old lites were led's, don't understand why they failed, but 3 have on the truck. They were put on last August. I'll check the trailer tonight when I hookup and do the pretrip for tomorrows run. They were not expensive, 60 bucks each so they will be going back when I return to Victoria BC. I will also look to see how many led's each one has and if possible get a name and part # to see if more can be found out.

I have been hanging around Americans too long where bigger is better and you can never have too much horsepower or "Go big or go home", is another one I heard.

The lights don't have to light up a city block, just the area adjacent to and under the truck fairings where the mirrors can start to see. Starting somewhere around the fuel cap area. The lites are mounted under the truck body and aimed down and out to illuminate as much ground as possible before being obscured by the side of the truck if aimed higher....if you understand. A patch 3-4' wide and 3-4' out from the side is adequate.

 

The 27 was referring to other lites on EBay, 27 watts as opposed to the 18 and 40's

 

I'm aware led's draw less 'cus the Magnum 2812 control panel only drops 5 amps when all the bathroom and bedroom lights are switched off. I think the old fluorescents were about 3 amps a fixture of 2 tubes each..

Floods are what I'm after, not spots.

 

Anyway these lites are pretty slick when parking at night. I put some of those reflective road cats eyes in a line where I want the trailer wheels to be and pretty much nail it. The trailer backup lites illuminate the road markers.

[jkoenig24]

A downside to adding extra lights is that ALL installed lighting MUST be operable; otherwise, you could be cited / ticketed and, may not pass an inspection.

[gjhunter01]

A downside to adding extra lights is that ALL installed lighting MUST be operable; otherwise, you could be cited / ticketed and, may not pass an inspection.

That's true for a commercial rig, I don't believe a private vehicle has the same requirement for added lighting required to work. The factory installed lighting must work.

Greg

[Nuke-E]

That's true for a commercial rig, I don't believe a private vehicle has the same requirement for added lighting required to work. The factory installed lighting must work.

Greg

 

It's actually not true for either. All required lighting must be operable on a commercial vehicle:

 

https://www.fmcsa.dot.gov/regulations/title49/section/393.9

All lamps required by this subpart shall be capable of being operated at all times. This paragraph shall not be construed to require that any auxiliary or additional lamp be capable of operating at all times.

[Alie&Jim's Carrilite]

A downside to adding extra lights is that ALL installed lighting MUST be operable; otherwise, you could be cited / ticketed and, may not pass an inspection.

I don't think Roger is using these lights while rolling down the highway. I, at one time, had the same thing. but I used 55watt halogen's. Mounted 2 in front of the axles pointed down and out, and 2 at the front landing gear. Had another 2 under the bumper of the Dodge. It was great having them to back into spaces at night, or to do a little roadside maintenance at night. Over time road debris killed them though.. broken lenses and housings, etc.

[jkennell]

A LED light that drew 4A---would light a city block! I have a couple LED lights on a farm tractor that draw 3A (36W) and they are BLINDING. They are rated at 3250 lumen, IIRC.

 

This whole confusion comes with the way the different ratings are done. A incandescent light of any type is rated by power used--Watts. As stated, Volts x Amps. How much light it actually produces is dependent an a lot of other things, like type of bulb (halogen, etc) and reflector. An LED light is super efficient, and they chose to rate it by actual light intensity rather than current draw (possibly because humans ALWAYS like "bigger is better", and who would buy a 5W LED when you could buy a 40W Halogen....even if the 5W LED had more light !!)

 

I think that one good "Point of reference" (at least for farmers) is the typical old 55W incandescent "utility light" found on machinery is roughly about 500 lumens. From experience, a 1200 lumen LED light is perfect lighting up areas like under a truck, or a grain tank on a combine....

 

There is one other factor to watch for in Lighting---beam angle. An incandescent filament throws light 360 degrees. It is then reflected and focused by the lensing on the bulb & housing. Hopefully most comes out the front as usable light...the lens determines the spread pattern (thin & far or wide & short). LED lights, on the other hand, are inherently unidirectional. They send light out in a fairly narrow beam, which must be spread by a lens to get a wider pattern. I'm not sure what the standards are for measuring Lumens--but I've wondered if some of the "Cheap" LED lights are very much a spot light, with the high Lumen rating because all the light is focused on that one spot. (They do that on panel indicator LEDs--you can buy a 5 lumen, 70 degree indicator , or a 25 lumen, 15 degree indicator---same LED, different lens, measured lumens right in front.) Maybe I'm just cynical.

[Darryl&Rita]

Used these before. Nice pool of light, without being super-nova.

[rdickinson]

I can see now how things run off the rails. I thought I was clear in the use of these lights, for backing into an RV pad after dark. Not going down the road or anything else. I have my CDL but like most others here the rig is not commercial.

Thanks A&J. Maybe some of these lights will light up a city block but not when it is 1 foot from the ground at a 45 degree angle. I've tried led work lights, they are bright but don't light up a room like a halogen...at least in my experience.

My lights have 6 led's in each one. Not able to get more info until I get under the truck and see the back of the housing.

 

I'll get either the 18 or 27 watt lites and order 6. 3 are dead and I want extras in case more fail.

[JEEPOHOLIC]

how about these ; http://luxlightingsystems.com/

[rdickinson]

Pete,

 

I went with your recommendation for the 18's. The intention is not to melt blacktop or be seen by the Space station. Just to get into a dark pad without going back and forth more than once as well as not hitting something and winding up on UTubes epic failures.

 

Thanks

[Big5er]

A downside to adding extra lights is that ALL installed lighting MUST be operable; otherwise, you could be cited / ticketed and, may not pass an inspection.

David (Nuke-E) beat me to it. Guess I should read the whole thread before responding, eh?

[rdickinson]

A downside to adding extra lights is that ALL installed lighting MUST be operable; otherwise, you could be cited / ticketed and, may not pass an inspection.

 

Give me a break. How many commercial and other non commercial vehicles plow down the roads with 1 or more lights out as well as other deficiencies.. At least I do a friggin precheck, find the problem and get it dealt with asap. And don't do a micky mouse fix. Any doubts, ask those who know me.

 

I didn't ask for a lecture.

 

This is not required lighting. The issue has been dealt with, subject closed.