DIY exterior RV LED light ?

[WVVan]

Hi All,
I'm converting a van into a RV. If you're really bored and want to kill some time you can see it at this link (warning it's very long).
I need some exterior lighting fixtures. Can't find anything just like I want so I'm going to make my own. The initial plan is to use a 2" PVC end cap to hold the LEDs. I'll drill a series of holes through the cap side and place the LEDs in the holes. Put the electronics inside the cap and then seal the whole thing against the weather. Feed it 12 volt from the "house" batteries.

I'll be using thru-hole type LEDs and want to use the brightest one's I can find. I've read "Don's 'LEDs with Punch!'" and other threads on the subject. The van uses 4x6 volt golf cart batteries (260 lbs) so I'm not that worried about efficiency.

I've looked at the brightest LEDs carried by Digi-key and Mouser and other retailers. But the brightest one's I found are from a ebay seller called Topbright. I'd provide a link but I don't want anyone to think this is some kind of a stealth ad, cause it's not.

They claim "10mm 40° 1W Watt White LED 300mA 380,000mcd". The thing is the "380,000mcd" figure seems so far ahead of what the legitimate sellers are carrying my radar goes off.

Has anyone had experience with these? When something sounds to good to be true on Ebay, it is. Even if the specs are true I'm curious how a thru-hole LED would dissipate the heat. I know from reading, just reading since I'm a newbie on this subject, the 1 watt surface mount LEDs require a good heat sink.

That's my first questions. Thanks for your time.

Dave

PS. Here's a Youtube of the electric sofa-bed I built for the van/RV: Youtube

 

[John_Galt]

Forget about low power LED's. Try to find a small finned aluminum box, get a 12 driver, and wire up three neutral/warm white Cree XP-G's in series with some optics.

Triple arrays, drivers, optics and heat-sinks can be found at Cutter.com.au

These will outshine any array of 5mm LED's, and last much, much longer. Yes, such a unit will be a little more expensive initially, but the additional life-time and durability will offset that cost.

 

[WVVan]

Thanks JG,
While your advice is probably best for most applications I'm going a different way with the van.
From this picture you can see the the van with the top up. The light fixtures will be attached along the edge of the pop-up top.

Metal boxes would work but I think the PVC caps will be less obtrusive. They have the same color and look of the fiberglass top. I know that thru-hole LEDs will never give the same amount of illumination as Cree XP-G's but deep in the woods in pitch blackness a little light can go a long way. These will be just for some general illumination around the van, not as work lights.

Once I make a couple prototypes and field test them I might find that the thru-hole LEDs won't do the job and I'll have to move to something brighter. I still want to try first.

Thanks again,
Dave

 

[Ken_McE]

The thing is the "380,000mcd" figure seems so far ahead of what the legitimate sellers are carrying my radar goes off.

For lighting a tiny point, Candelas is a reasonable measure. For lighting a broad area I prefer Lumens, since that is a measure of the total light output of the emitter, not the light recieved in a small area.

I'm a little vague about how the lights will be arranged in their PVC domes, and how they're set up to not be crushed when the roof closes, but I expect that'll be clearer in later posts. Will they aim at the ground? Will they be aimable? Are they set up in clumps? Dots? bars of light?

A light that I might use in that situation would be the Acolyte Led strip. They use Superflux emitters and they're waterproof straight out of the box. Less fun than DIY, but pretty effective. They would tend to give you an even wash of light, like fluorescent office lights, rather than beams or spots.

If you're feeling wild, you could get some of those RGB LED underbody lights and mount them under the van. While on the road you could set them to some inoffensive color like white or yellow and make the van highly visible when driving at night. When your parked somewhere you could use them for ambiance lights in any color you like, or cycle them for cheap entertainment. :rock:

 

[JohnR66]

If your looking for light that is not too bright, nice color temp and low power, check the Radio Shack 276-0017 LEDs. 3 in a series with a 150 ohm resistor per fixture will give plenty of light with efficient use of the voltage drop for a 12 volt system. If you had six fixtures, three on each side, total power usage would be around 120ma with engine off. They would run for days of those batteries.

Avoid the eBay LEDs. Lots of poor quality junk with inflated ratings. I test LEDs and those 55,000mcd 5mm leds test out to around 15,000mcd with my meter and last only 3 or four days at 30ma continuous duty. The Rat Shack LEDs previously mentioned are wider angle so mcd won't be high but it tests accurate and are at 6,000 hrs and going strong in my test.

 

[WVVan]

Hey Guys,
Here's a quick drawing of what I'm planning.

The number and placement of the LEDs will depend on how they test out..

A light that I might use in that situation would be the Acolyte Led strip.

Don't think these would look that good on the outside of the van and not sure how to aim them.

If you're feeling wild, you could get some of those RGB LED underbody lights and mount them under the van.

Lights below the van wouldn't help much in seeing what's outside

I came up with the outside light idea when I was camping a couple of weeks ago. In the middle of the night something started rooting through my campsite and woke me up. I stood up in the van and looked outside through the screen sides of the pop-top. It was pitch black and it occurred to me that if I had some lights on the edge of the pop-top I would be able to see all around the van without having to search around with a flashlight, which is what I was doing.

I wasn't holding out a lot of hope on the ebay LEDs so went ahead and ordered the brightest white through-hole LEDs I could find at both Digi-key and Mouser today.
Digi-keys were the Cree C503C-WAN-CBADA151
Mouser was Lite-On 859-LTW-2S3D8

I'll have to see how bright they actually appear.

Next question. Once i get all the LEDs and electronics together I was going to weatherproof the PVC caps by filling the inside with silicone, epoxy or fiberglass resin. I've never actually done this before I don't know if it will work. Has anyone tried something similar?

Thanks again,
Dave

PS. The more I think about the undervan lights the more I like them. Just for fun they'll be a real hoot in the woods.

 

[mvyrmnd]

A friend of mine was having this same problem. He was trying to read a newspaper by the side of his RV and just couldn't get enough light.

The solution I though of (once I can find someone to manufacture the required parts) was to build a block on a swing arm that a D36 pill could screw into. I was going to get a warm MC-E 12V pill, and screw it back into the block and then cover it with a frosted dome. This would more or less be like a mule head with a frosted lens.

This should give you a reasonable flood, which can be pointed in any direction. You could even use a 3 mode driver, so you'd have dimming ability. The block would be the negative side of the circuit, and the positive wire could be fed back through the block and swing arm. This could be wired directly into the vehicles 12v system.

If yours is a 6V system, just get a regular driver. You could even use a P60 pill.

This way you have a very bright, directional, dimmable light that can be upgraded easily.

Two or three of these should provide more than enough light.

I call dibs on a patent if I can get a prototype built!

 

[JohnR66]

I like the PVC cap idea. It should work well. You should put 6 LEDs per cap since 3 LEDs in series with a 100/150 Ohm resistor is a simple, efficient way of using 12 volt power. Using one LED per resistor means most of the voltage is dropped in the resistor. You might as well use regular incandescent in that case.

The Cree C503C-WAN-CBADA151 specifies a wide range of brightness. The baggy you receive will have the actual bin on them. Too bad you already spent the money. I could have sent you C503C series whites for the cost of shipping (a couple bucks). The Cree LEDs are excellent quality. If mainly used with the engine off, I'd say you are safe to use 100 Ohm resistors.

I don't know much about the Lite-On brand LEDs.

 

[WVVan]

Hey guys,
I wasn't too worried about making the lights bright enough to read by. I have a headlight I use when I want to do something like that.

Much gratitude for the offer of the LEDs JohnR. But when you consider the cost of converting a van to a RV ( new RV's are around $90,000) the LEDs by far one of the cheapest things I'll be buying. I still appreciate it though.

A good idea about not running the lights with the engine on to reduce the power spread I'll have to worry about. To enforce that I'll locate the on switch in the "house" area and not in the "cab" since these are meant to be camping and not running lights.

Later,
Dave

 

[Ken_McE]

I'm curious how a thru-hole LED would dissipate the heat. I know from reading, just reading since I'm a newbie on this subject, the 1 watt surface mount LEDs require a good heat sink.

What you are calling "Though hole LEDs" I believe are what I would call 3mm and 5mm LEDs. They are shaped like a little bullet, have two wires sticking out the flat side, and emit light on the rounded end.

To the best of my recollection, all of these little fellows are small enough that they don't noticably build up heat, and the issue can be ignored. My rule of thumb is that I begin thinking about heat when I get a unit that pulls one watt or more. Smaller than that I don't feel they need a radiator.

I have some question about whether you can squeeze enough of these into a 2'' cap to be more than a night light, but hey, maybe you can. How will you mount them to the vehicle?

PS. The more I think about the undervan lights the more I like them. Just for fun they'll be a real hoot in the woods.

They can actually be useful. You pull in somewhere, you're talking to someone, you want them to meet you at the van later, if you can say "Look for the white van with the orange light under it" you're easy to find. Or lets say you set up at an event somewhere, your in a flat grassy field with 500 tents and vans parked all over, you don't know the site that well, if you can just look for the pink and blue lights it's a lot easier to find your camp in the dark. I have found that just having a few 3 or 5 mm leds shining up at the inside of a tent makes it a lot easier to find in the woods.

 

[WVVan]

If you're looking for LEDs at the Mouser site they are all sub categorized as either "SMB" or "Through Hole". Similar setup at Digi-key.

I have some question about whether you can squeeze enough of these into a 2'' cap to be more than a night light, but hey, maybe you can. How will you mount them to the vehicle?

I have the exact same question about whether it will be bright enough so I'll answer it by building one or two of the fixtures and field testing it. I freely admit that this might not work but you never know unless you try. I've already come up with a couple ideas how to do this with surface mounts if the through holes don't pan out.
To attach the fixture I'll drill a hole through it's center and the fiberglass pop-top then bolt them together.

you don't know the site that well, if you can just look for the pink and blue lights it's a lot easier to find your camp in the dark

Excellent idea. Hadn't thought of that.

 

[Ken_McE]

Thread about LED light built into a 2'' PVC cap:

http://www.candlepowerforums.com/vb/showthread.php?t=287640

 

[WVVan]

That's similar to what I have in mind but I'll mount the LEDs so they don't extend outside the edge of the cap.