Introduction: 36 Volt - 900 Lumen LED Stadium Lights

Picture of 36 Volt - 900 Lumen LED Stadium Lights

The end of daylight savings and no lights meant that 5:30 pm soccer practice would be totally dark. With field space severely limited this meant the end of practices.  Next year we will be ready with portable battery powered field lighting, thanks to low cost, high power LEDs and lightweight long lasting lithium 36 volt battery packs from Dewalt.

I built two stadium lights. Placed on opposite sides of the field they do a nice job of lighting a decent size practice area for 10-12 kids. For a larger field or different sport, you may need several more. Each light draws ~.750 Amps, the Dewalt pack is good for 2.3 Amphours or not quite 3 hours. Still more than long enough for practice. 

Needed  36 Volt Dewalt Lithium battery pack
These things are great, lightweight, fast charging,  and very convenient after you have followed the directions to add standard power out wires. I will not detail how to disassemble the battery as this is readily available on the internet in several places.
http://www.slkelectronics.com/DeWalt/packs.htm
http://www.youtube.com/watch?v=qQJUEeKo7KQ
9 STAR LEDs (3 watts ~100 lumen each now available direct from China for around $2 per LED, ebay and other sources)
Most  of these high power, high efficiency LEDs operate from 3.5 to 4.0 Volts.  To save money we are not going to use the recommended constant current driver, but wire directly in series. (36 V / 9 LEDs) = 4.0 volts per LED.
CPU style heat sink
1 ohm, 10 watt resister (to add some safety margin)
18 inch long piece of aluminum angle (1/16" by 1 inch)
JB Weld Epoxy
1 inch hose clamp
10' x 1/2 pole (PVC pipe)
Screws, wire, solder








Step 1: Solder Leads to the Star LEDs

Picture of Solder Leads to the Star LEDs

STAR LEDs are very nice to solder. They have wide solder pads, clearly marked + and -.  Start with the plus side and solder one lead to one + pad.

Step 2: Continue Soldering All 9 LEDs and 1 Ohm Resister in Series

Picture of Continue Soldering All 9 LEDs and 1 Ohm Resister in Series

Solder your leds into a series circuit.  The first wire goes to the + pad on the first LED.  Solder the second wire to the - pad of the first LED and solder this same wire to the + pad of the second LED. The next wire goes from the - pad to the + pad of the third LED. Continue until all 9 LEDs are soldered in the string you see below.  Next solder one terminal of the 1 ohm resister to the last wire and solder two 10' lead (+ and -) wires to the ends.

Step 3: Epoxy the STAR LEDs to the 18 Inch Aluminum Angle

Picture of Epoxy the STAR LEDs to the 18 Inch Aluminum Angle

3 watt LEDS at full power may generate enough heat to eventually destroy themselves unless applied to a heat sink.  You could buy special thermal epoxy but JB Weld brand epoxy appears to have enough metal to bond the LEDs and work as  transfer heat. Bond all your LEDs to the aluminum and clamp firmly in place for several hours.

Step 4: Add Heat Sink, Hose Clamp and Test Your Lights

Picture of Add Heat Sink, Hose Clamp and Test Your Lights

With the LEDs on the aluminum angle will become quite warm.  Adding a heat sink (from a CPU cooler) is a good idea to maintain efficiency and LED life.  Bolt on a hose clamp for mounting your lights to a tall pole. Plug in and test your lights.

Step 5: Light Up the Night.

Picture of Light Up the Night.

Mount the LED to a pole. I have used 10 foot conduit but the LEDs are light enough that PVC pipe works well too. Light up the night and enjoy.

Comments

Sbauer9 (author)2016-10-30

I don't know what happened to my previous message I guess it accidentally got caught in our conversation somewhere! Anyways I'd appreciate it if you could give me some feed back on my idea! So I plan to use a 24v drill battery and wire 7 of these LEDs in series http://m.ebay.com/itm/5-x-LED-3-Watt-Cool-Clear-White-Star-Bright-Wide-Angle-High-Power-LEDs-3w-w-/151187143805?_trkparms=aid%253D222007%2526algo%253DSIC.MBE%2526ao%253D1%2526asc%253D20150519202348%2526meid%253D85ca3f1e7a344f2da881623acc8cb078%2526pid%253D100408%2526rk%253D5%2526rkt%253D25%2526sd%253D151171352633&_trksid=p2056116.c100408.m2460 that would leave each LED with just over 3.4v each which is right in the middle of their reccomended voltage. I think the battery I'm going to use is an off brand replacement for a dewalt 24v https://www.amazon.com/gp/aw/d/B00760WJ0G/ref=mp_s_a_1_11?ie=UTF8&qid=1477831550&sr=8-11&pi=AC_SX236_SY340_QL65&keywords=24+volt+drill+battery because of the price. I think the resister you reccomended in the instructable still will be the right one (correct me if I'm wrong). Do you mind also providing a new link or explaining how to disassemble the battery in order that it is usuable? The links do not work. Thanks again for everything

pobriant made it! (author)Sbauer92016-11-09

It sounds like you've done some good research and have a solid plan. With today's options it may not be the easiest. But yes, go for it. You are guaranteed to learn a lot and hopefully have some fun.

You asked if the 1 ohm, 10 watt resistor was the right size. Instead for your specific setup I might recommend a 0.2 ohm resistor. (Still make sure you are using the wire wound resistors with 10 watt or preferably greater.) One way to calculate V = IR. 24V(input) - 23.8 (7x 3.4 (V drop)) =.2 V / I(spec on your leds = 1 amp) = 0.2 ohms.

You asked for drill battery hack links. Because easier options are now available, I do not think hacking a drill battery is really worth the time or effort for a simple low power system. But just my opinion and your mileage may vary. You will learn some interesting stuff. Again, go for it. Start here:

https://www.rcgroups.com/forums/showthread.php?t=5...

http://makezine.com/2007/09/05/breaking-down-and-r...

So ...... if you want to take a much, much easier approach (maybe too easy?)

https://www.amazon.com/gp/product/B01DJOZ78S/ref=o...

Keep It Simple - For around $7.50 apiece, these 12 Volt LED fog lights make great spot lights. Why do they work so well? These LEDs are driven by a constant current that matches and optimizes the LEDs, even as the voltage from your batteries drop. And it's got great heat sinks, is low cost, incredibly robust, and incredibly bright.

Power - I love lithiums. But..... for small systems like your lights, the new NiMH are so much easier. Not worrying about fires is really really nice. 8 rechargeable AA batteries in a pack. As the lights actually pull about 1 amp, the 8 Eneloops with ~2100 Ahr capacity will last > 2 hours. At ~$20 are a bit more expensive but probably worth it. Claimed 2100 charge/discharge cycles.

Sbauer9 (author)Sbauer92016-10-30

Another thing I could do probably is use 1 of these for each LED I have https://www.amazon.com/gp/product/B01COPLDMM/ref=abs_brd_tag_dp?smid=A3MH3MAWW32XOH this is probably cheaper than the drill battery option anyways. What do you think?

Sbauer9 (author)Sbauer92016-10-30

I'd probably use this brand though since it has better reviews https://www.amazon.com/gp/aw/d/B00IOCCDBK/ref=pd_aw_fbt_23_img_2?ie=UTF8&psc=1&refRID=QB817GKA3TYX9K7WQVMT

Sbauer9 (author)2016-10-25

Thanks for the great DIY. I have been looking for something like this for wiffle balls in the yard. I have a few questions though. 1. What kind of LED's would you reccomend going with now with the advances in LED technology? 2. Do you think I could get these LEDs in 110v so I can use them on house voltage? The reason I would like to do this is so that I can get the light directed down onto the field from higher than just a normal halogen work light stand. Any ball hit high at all gets lost in the sky because there is no light up there. Also, I think I can get a brighter light and a more efficient fixture with LEDs opposed to the halogens. Thanks for your time.

pobriant (author)Sbauer92016-10-25

Hi Sbauer9,

Wow, I had not thought about this hack in several years. Well done, you found a moldy oldie here. And you absolutely nailed the right question here, LED technology have advanced tremendously. Much simpler and easier to do now. Here is how I would solve a similar problem in 2016.

1)Yes, absolutely if you have access to 110 volt AC power, plug in with a set of outdoor extension cords.

2)These clamp type plugin fixtures are a simple and low cost approach. Can you get high enough by mounting to a ladder leaning on your house, make some tall poles or maybe a have a tree you can throw a rope over clamp on to the rope? Just be safe out there.

https://www.amazon.com/Bayco-SL-302B3-Brooder-Porc...

3) It's now pretty hard to beat the quality and price of standard screw in LED bulbs, especially from places like Home Depot and Amazon. High efficiency, robust to damage, and fairly inexpensive.

Something like these?

https://www.amazon.com/Philips-455717-Equivalent-Daylight-4-Pack/dp/B00YEMKJE2/ref=sr_1_4?ie=UTF8&qid=1477454241&sr=8-4&keywords=led+bulbs+100+watt

Sbauer9 (author)pobriant2016-10-26

Thanks for the help and quick reply despite the age of this thread. I'll take a look into those. Oh, I'd like to compliment something in your design that I do not think a lot of people caught. I think it is a great idea on how you put the aluminum angle. I see that this forced all the light from the LEDs down onto the field. This won't be a problem with clamp on lights, but without that design, you would lose light upward. Great job and thanks for all your help.

Sbauer9 (author)Sbauer92016-10-26

but if I wasn't going to go with the clamp on lights, and I would opt to use something like the 3 star LEDs, what would you reccomend there that double be wired to 110v? Thanks

Sbauer9 (author)Sbauer92016-10-26

Sorry to bother you so much but I appreciate all your time and effort. Similar to in LEDs, there have been huge advancements in batteries too. I have an application similar to yours at a local youth football league that could use something. What kind of battery would you reccomend today, and would it be any cheaper that the $150 drill battery? Thanks again for your time, it will be put to good use!

pobriant (author)Sbauer92016-10-26

Hi Sbauer9,

Another great question. Batteries have come quite a ways too, just not nearly as fast as LEDs. Hopefully in the next couple of years with more electric car companies, electric bikes, the Tesla battery factory and other manufacturers coming on line, lithium battery prices will start to drop soon. One online supplier (and a whole lot easier to use) is the 12 Volt Battery Tender -

https://www.amazon.com/Lithium-Phosphate-240CCA-Re...

https://www.amazon.com/Battery-Tender-022-0198LI-P...

And with a 12 volt battery you could either use just 4 STAR LEDs in series or and this is much easier (but does lose efficiency as converting twice) plug the batter into a 12 volt DC to 110 volt AC inverter and then power standard commercial 110 volt LED bulbs.

https://www.amazon.com/Power-Bright-PW400-12-Inverter-Watt/dp/B000OOZY5S/ref=sr_1_1?s=hi&ie=UTF8&qid=1477537861&sr=1-1&keywords=power+inverter+12+volt+dc+to+110+volt+ac

Sbauer9 (author)pobriant2016-10-27

What do you mean by 4 Star LEDs? Thanks

pobriant (author)Sbauer92016-10-29

HI Sbauer9,

Sorry, for the short cut. The more standard name to search for is "quad LED emitter". As I'm sure you are aware, each standard high power power LED emitters need to be driven by a voltage source fairly close to 3 Volts. So in LEDs wired in series, each LED drops the voltage by around 3 Volts. (My original instructable, I wired the LEDs in series (and when I accounted for the not quite 36 volts the Dewalt battery delivered plus losses and found it worked best for qty 9 LEDs wired in this series arrangement).

And.... these days the LED manufactures will do the series wiring for you. This is the quad LED star. 4 LEDs on one STAR, and instead of driving them at 3 volts. Below is one example of a quad star LED emitter. The specification says to use 11.6 to 13 volts. (Or a fairly typical 12 volt battery)

http://www.luxeonstar.com/cool-white-5650K-sinkpad...

Sbauer9 (author)pobriant2016-10-30

I think I'm going to avoid the quad star because of the high price. As you can probably see, I'm trying to work around a fairly tight budget for each pole. Thanks for the idea though. I've got a plan laid out and it would be great if you gave me your opinion on it. I would use these as my LEDs http://m.ebay.com/itm/5-x-LED-3-Watt-Cool-Clear-White-Star-Bright-Wide-Angle-High-Power-LEDs-3w-w-/151187143805?_trkparms=aid%253D222007%2526algo%253DSIC.MBE%2526ao%253D1%2526asc%253D20150519202348%2526meid%253D85ccf6e45d4e43f3bf736958eef57af6%2526pid%253D100408%2526rk%253D5%2526rkt%253D25%2526sd%253D151171352633&_trksid=p2056116.c100408.m2460 and I'd use 7 of them. The reason for this so that I can get each LED to plus or minus 3.4v which is right in the middle of their reccomended voltage. Like I said before, I'd power them with a modified 24 volt drill battery. At this set up would you still go with a 1 ohm 10 watt resister? It's been a while since I've done a project where I've had to calculate the resistance needed, so I'd appreciate it if you could help. Thanks again for everything

Sbauer9 (author)Sbauer92016-10-27

Maybe these? https://www.amazon.com/gp/aw/d/B00ZWOYV7C/ref=mp_s_a_1_3?ie=UTF8&qid=1477621172&sr=8-3&refinements=p_85%3A2470955011&rps=1&pi=AC_SX236_SY340_QL65&keywords=3w+led+emitter&dpPl=1&dpID=41mYat3sEBL&ref=plSrch

Sbauer9 (author)Sbauer92016-10-27

If I had a pad of paper in front of me, I could do the math, but if I only put 8 Star LEDs on 1pole opposed to 9, would the amperage allow me to get to a smaller and cheaper battery? If so what would you reccomend?

pobriant (author)Sbauer92016-10-29

Hi Sbauer, It is pretty easy to overdrive (too high voltage plus too high current) and burn out the LEDs by over heating. Read the voltage specifications for each LED. 10 years ago virtually the only emitter (bright) LEDs available required around 3 volts. But if you wired 8 in series, then 8x3 volts = at least 24 volts. (add a little extra to account for voltage drop across each). So you could use a modified 24 volt drill battery or 2 x 12 volt batteries. But with LED suppliers now offering other prepackaged solutions like the quad star (4 in one I wrote about above) that take 12 volts, you may want to keep it simple approach and low cost with rechargeable 8 AA batteries.

https://www.amazon.com/8pcs-Cells-Battery-Holder-B...

pobriant (author)Sbauer92016-10-29

Sure, those should work if you wire 4 in series.

pedude (author)2012-08-28

Not sure my priv message went through couldnt read the captcha thing. sorry if it did for repeating these questions. I am totally going to try to make your awesome field lights. I had some questions: how big a square feet or yard area do they light up? about how much per light stand did they cost? could I make it brighter if need to with a different battery and or light set up? I have about $250 per light stand. Is it difficult to change out lights if burn out and do they last before burning out. I only need them to work about 1 to 2 hrs per time. I am a p.e. teacher trying to solve basically the same problem you had, i have no experience doing this type of thing, is it not too difficult. thanks for any help this solves a huge problem and saves the day if i can do this, i havent seen anything out there to purchase to solve field problem. thanks, Mike pedude70@gmail.com

pobriant (author)pedude2012-08-29

Dear MIke pedude,
You have a bunch of really good questions. I will take a shot, one at a time.

Before you start down this path, can you get access to an electrical outlet? If the answer is yes then I recommend Keep It Simple (and cheap). It may not be elegant solution but if you have access to power, for an hour a day it will be nearly impossible to beat the lumen/dollar value from a set of electrical cords and halogen work lights. Go to Home Depot, Lowes, Amazon and get as many as you like.
http://www.amazon.com/Bayco-SL-1002-Halogen-Project-Light/dp/B000FW7UH4/ref=sr_1_3?ie=UTF8&qid=1346278571&sr=8-3&keywords=halogen+worklight
Mount these on tall poles and be done.

Because the world of LEDs this design now 3 years old and likely obsolete.
for the latest in LEDs and questions go here:
http://www.candlepowerforums.com/vb/content.php
for low price LEDs, search Ebay or here:
http://www.dealextreme.com/

how big a square feet or yard area do they light up?
With two sets of lights I lit 1/2 a youth size soccer practice field, roughly 30 yards by 30 yards. And for soccer low lighting is still "ok" as long as the players can see the ball fairly well. For a larger softball or baseball this you would need brighter (and higher lighting) and I would not recommend a low cost DIY approach. Use your best judgement.

about how much per light stand did they cost?
The light stands (LEDs, brackets, poles, wires, etc.) were around $30 total. Unfortunately the killer is the Dewalt 36 volt Lithium battery pack. Even on ebay these run between $90 and $120 each.

could I make it brighter if need to with a different battery and or light set up?
Absolutely. The easiest approach would be to simply to double, triple, or quadruple each light strip and add parallel connections to the power supply. More lights (or higher wattage LEDs = more lumens).

I have about $250 per light stand.
Should be doable.

Is it difficult to change out lights if burn out and do they last before burning out?
Yes. In the current configuration the LEDs are soldered in parallel. If one burns out the string goes down and you would have to desolder, twist off, resolder/epoxy. Fortunately the life listed for thees LEDs are 2,000 - 25,000 hours depending on power/heat. With one evening practice every day the LEDs might last between 5.5 - 50 years.

i have no experience doing this type of thing, is it not too difficult?
Jumping in and getting the experience is probably the biggest challenge. LEDs are fun, cheap, and simple. Get dirty, take chances. I do have one word of caution for the power supply. The Dewalt battery packs are portable, long life, light weight, fast charging great in many ways but.... they are somewhat pricey and when you open them to solder in a wire you have a high current source exposed. Please watch the video carefully.

http://www.youtube.com/watch?v=qQJUEeKo7KQ

Decide if you feel comfortable doing this. If this is your first electrical project I might recommend another power source. Perhaps three 12 volt lead acid batteries in series in a box or handtruck would be cheaper and easier to start.

pobriant (author)pobriant2012-09-01

http://www.dealextreme.com/p/prime-100w-8000lm-led-emitter-metal-plate-pure-white-42806?item=176

As an example of how the LED world has changed in 3 years, dealextreme ( ~$67) is now selling a single LED module with an advertized output of an incredible 8000 lumen . One LED now has almost 10X the (8,000 vs the 900) light output of all nine LEDs shown in my instructable from above. (Of course you better mount that 8,000 lumen LED on a very good PC processor type heat sink, preferably one with a fan or liquid cooling).

rimar2000 (author)2009-11-29

Interesting.

Besides portability,
does this device advantages over a low energy lamp connected to the mains?

pobriant (author)rimar20002009-11-29

If you have an electrical plug easily available, I would recommend keeping it simple and plugging in with standard lighting. The soccer field is 1/4 mile from my house and my extension cords are not that long.  But if you needed a combination of high efficiency and robustness (where the light was going to be knocked around a bit) a plug in LED solution might be the best. High power LEDs are much more efficient than standard incandescent or halogen bulbs.  And much more robust then florescent bulbs.

rimar2000 (author)pobriant2009-11-29

Thanks for the answer.

I forgot to ask something that interests me more: are LEDs more expensive than equivalent  "ordinary" lamps?

pobriant (author)rimar20002009-11-29

You just asked the multi-billion dollar question that is driving today's lighting industry. The answer may be  "it depends on when you ask". 

The one thing most agree on is that  the standard cheap incandescents have lost. Go to Home Depot and on sale you can get a 60 watt incandescent bulb (claimed 15 lumen/watt = 900 lumens) for around $1. Plug it in for 24 hours a day and you will spend ~$52 of electricity.  (60 * 365 *24 / 1000 watts/kilowatt) * 10 cents per kilowatt hour, about US avg. (total $53)

The el cheapo $2 LEDS I used are about twice as efficient, 33 lumens/watt. So 9*$2 = $18 but I would only use $24 of electricity per year. (total $42)

Gross simplification and does not include fixtures, AC/DC converter, converter  efficiency,  replacement bulbs, etc. But you get the idea. Invest now, save later.

Today florescent  (up to 100 lumens/watt) easily beats both for most applications but are not robust for banging around as portable lights or smashed by an errant soccer ball.  Cree/Seol/Nichia/Philips all claim to have next generation LEDS with efficiencies from 130 to 150 lumen/watt.  And where LEDs may make sense today is if you are off-grid and already running DC power.


rimar2000 (author)pobriant2009-11-29

Thanks for that excellent summary of the situation. In my case, I will follow the mainstream, replacing filament lamps by low power as they get knocked out.

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