The biggest LED COB panel yet! Voltage/current tests.

This thing is huge and bright. It runs at around 12V, but has no integrated current regulation. This means that if connected directly in a vehicle application the current could be very high and the voltage drop across the supply cable will be a factor in limiting the current.
The circuitry is basically four large parallel arrays of LEDs connected in series to make up roughly 12V combined forward voltage. I did some voltage/current tests as follows:-
10V 7mA 70mW
10.5V 170mA 1.8W
11V 790mA 8.7W
11.5V 1.72A 19.8W
12V 2.85A 34W
12.5V 4.2A 52W
12.8V 5.2A 66W Current Limit of bench supply.
As you can see form the voltage to current ratio the current increases significantly with a small voltage change.
A typical eBay search for this might be:-
www.ebay.com/sch/i.html?_from...
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.com/coffee.htm
This also keeps the channel independent of KZbin's advertising algorithms allowing it to be a bit more dangerous and naughty.

[@fogllama]

I bought several of the smaller size Clive played with in a previous video. I am using a 555 timer based PWM to dim it, and a 6.8 ohm current limiting resistor. Been running it for hours and it is still running cool. Thank you Clive for finding and playing with these things.

[@vicmiller7191]

I just love you fascination with lighting effects. A very neat panel indeed...Thanks for the Demo.

[@twocvbloke]

It's amazing to think how LED lighting has evolved in the past 15 years, from large lumps of layered PCBs filled with 5mm or 3mm white LEDs, to flat panels of LEDs like these pumping out 70 Watts of light, it's impressive... :D

[@tncorgi92]

30 years ago I was playing with components in my Grandfather's workshop, making random circuits, and he always told me to take it easy on the red LEDs because they were so expensive. Like a dollar apiece or something. These days we just throw crap away unless we absolutely need to save it for something.

[@mathuetax]

I guess what amazes me is the sheer light output. The first LEDs I played with (surplus HP and Monsanto) were only useful as indicator/pilot lights where there wasn't a lot of bright ambient light.

[@hippopotamus86]

70 watts of heat and light.

[@gordonlawrence4749]

I was working on LED's for Arrow Electronics (distributor) for lighting back in the 90's. Back then they were really rubbish but it was obvious the tech was on the way.

[@Tekwyzard]

Similar here. When I was a kid 35 ish years ago, I treated myself to my first LED, a yellow one. Blue ones, white ones, and UV ones weren't even a glimpse in some mad scientists eye yet. Anyway, during one of my dangerous experiments involving a mains transformer, I ignorantly left out the current limiting resistor, and melted the poor thing. It actually stayed lit as the plastic melted, at least until the leads parted company anyway, then I got an electric shock from the dangerously bare mains side as I unplugged it in a panic, hahaha, bloody kids eh?? I doubt any modern LED would even get close to surviving that punishment. I was gutted though, that LED cost me a fortune, and I stupidly killed it. Was lesson learned though. I'm actually using some 30 ish year old red LEDs for a project at the moment, because the colour and brightness of modern ones is just wrong and not in keeping with the setting in which the equipment will be used. I love the colour of those old LEDs :-)

[@gorinator]

Just want to point out that your video descriptions are top notch. Normally the only suggestion of how the viewers could get something is an Amazon affiliate link, where we find an inflated price. Here we get the right ebay search, with the right filters already on, so that we can get the best possible deal. Thanks for looking out for us Clive.

[@fraaggl]

Wohaou ! This one is my favorite COB for now on ! I bought two before the end of your awesome presentation !

[@BergRD]

Nice! Got some of the smaller types you showed a video or 4 back. They work great and only 1 out of 6 had bad LED's on board but the light produced even at 12v is so overwhelming it's not even noticed. Good stuff and thanks!

[@Rider19Ih]

Thanks dude for making this video with the current testing and such. Been looking into these large COB panels for a project.

[@StefanHartmann-hartiberlin]

Wow, I must get this... great big COB element ! Many thanks for the info.

[@johnbrookbank2969]

New projects in future for sure ! Thanks for the great info !

[@ImigrentfromMars]

THis just showed up and I can't believe it's been 5 years already, I bought some of these when you made this video,

[@furryearrapeuniverse324]

Is it weird i find these videos oddly relaxing? Clive's soft voice and smooth lighting in the videos really make me relaxed.

[@LazerLord10]

I really want to buy these, but I don't need any more of them. Time to start a new project, I guess.

[@thomasmcdougall614]

LazerLord10 make a grow light from them

[@agvulpine]

Thomas: Just peel off the phosphor?

[@NGC1433]

Use them as tiles in a bathroom...

[@NineSun001]

Exactly my thought. I soon have a new bench light :-D

[@braeburnhilliard8340]

That is pretty neat. It looks like it could be a lot of fun!

[@LongPlaysGames]

That thing is huge! I probably need one to light my work bench now :)

[@tazz1669]

Thanks Clive another great video. Makes me want to tinker and get the son involved in soldering which is a very useful skill for mending broken stuff, I've fixed lots of stuff over the years sometimes just by resoldering a wire or 2 where most would just chuck it out and buy another. Feel I need to buy some project boards so I can get him away from his Xbox for a while.

[@tncorgi92]

soldering is a good skill to have... I learned when I was a teenager and even though none of my jobs have been the type to require soldering skill, a situation always comes up where something is broken and someone says, "Does anyone here know how to solder?" You can be the one who saves the day and gets remembered when other opportunities arise.

[@-yeme-]

open his xbox and desolder a wire from something. too sneaky?

[@tazz1669]

yeme only if I wanted to die. Spoke to him today about it and he seems really keen. Result for dad I think, have ordered a few little boards to try out so hopefully my soldering skills are up to the task and he picks up this skill. I'll soon have him watching Big Clive with me :D

[@ryandrew8075]

Saturday mornings aren't complete without a Big Clive video

[@rodrickau]

Sent you coffee, Great video presentation. Should be in all schools. Thanks.

[@agentbertram4769]

Excellent video Clive! I must away and order one of these!

[@ArifKamaruzaman]

Another cool-to-have LED on the shelf right there.

[@JuanHerrero]

I like the "dumb", no inbuilt regulation stuff. That way you can put exactly what you want, and run it with no loses with a "barely enough" power supply.

[@PrintingPerspective]

This LED look insane :) as I saw it, I immediately thought what kind a project I can make with it! ;D

[@ianhill20101]

Good effort for the destruction test. Very informative top guy.

[@mikerhodes9198]

Take it outside at night and fire it up. Let's see what it looks like.

[@4DRC_]

In awe at the size of this lad.

[@victorcrumvictor5665]

nice video and Spectacular testing .. i love it

[@-yeme-]

0:30 almost all these ebay sellers are drop shippers. they hold no stock, they never even see any of the stuff they sell. they just list stuff on ebay and pass orders and payment, minus their cut, onto big warehousing and mailing services. thats why you see the same items with the same photos and identical descriptions listed by dozens of different sellers. you could pick any of those identical listings and no matter who you order from, it will come from the same place.

[@mrgreenswelding2853]

yeme that would explain things.

[@rodsofgod6863]

They all are drop shippers!!! All of them..

[@Debbiebabe69]

I just read up about 'drop shippers' yesterday. I always assumed the term referred to people that do business by using services that drop their shipment rather than deliver, for example myhermes, but it in fact a completely different meaning - stockless middlemen that just redivert their orders to China.

[@mrgreenswelding2853]

I just bought one from an Australian seller. It will still take over a weekto get here. Something that should take less than a week.

[@gorinator]

For some context, it's still called 'drop shipping' if it isn't the entire business model. For instance, where I work we make custom building materials. We drop ship the installation hardware. This way the customer only has to make one order, gets exactly what they need, and doesn't have to pay to ship it twice.

[@javiertorres7970]

I bet you can make some amazing grow lights, Clive.

[@neville3151]

While i enjoy watching you taking things to bits, very often i buy those items just to check them out for myself. Now i have a large drawer full of assorted little toys.

[@SeaJay_Oceans]

Looking forward to the 8.5" x 11" sized LED panel. :-) Light up the Night !

[@DigitalIP]

I use smaller 10w versions of these for Yard illumination using an AC-DC 60w 5amp power brick, they do very well for that. I also have 1 on my Tahoe as an extra Reverse/Illumination light connected to a cig lighter adapter.

[@ReeceM69]

Love the cob lights. Got them in my car

[@6F6G]

For automotive applications this lamp would benefit from having a basic 2 transistor constant current regulator so the light output doesn't vary depending on whether or not the engine is running.

[@gordonlawrence4749]

The first thing that went through my mind was bulkhead light. I'm pretty certain there are some cases roughly the right size for that. They would fit a small PSU too so you could feed them with say 36-48V reducing your feed current.

[@10p6]

Nice. I put two RGBW panels on my sound bar for graphic equalizer, and the specs says needed 76 watt PSU for each panel of 8 x 32 LED's for 256 LEDs per panel. Well 76 watts blinds you. In reality, even hidden behind speaker cloth, in daylight, the panel is perfectly visible at 2 watts per panel. The sound bar is on my channel if you want to see it.

[@ranger175a2w]

Thanks from Texas Clive

[@sincerelyyours7538]

This looks like a really neat idea. Some vendors are now selling an impossibly small looking LED dimmer for this COB array that they say can handle up to 12A and deliver 244 watts(!) on 5-24V DC -- all for $2.75 delivered. Ooooookaaaaaay, lets see if it works. If it does the lamp should work well mounted on a homemade aluminum slide suspended underneath the top equipment shelf of my new electronics bench. Thanks, Clive!

[@TheFlacker99]

I got 2 of those driverless led's at 100 watts each. Fantastic light, puts out a ton of heat though with a giant heatsink.

[@GadgetBoy]

I might have to get one of these to look at. I recently picked up a 1000x usb microscope. It's good enough to see the bond wires on the COBs.

[@danielczech560]

Thumbs up for your videos! I really enjoy watching them. I bought six smaller COB LED panels with each 50 watts to give my pepper plants a little boots of light for winter time. But they heat up quite fast and i got about 70°C after 7 minutes with one of them mounted to a passive cpu cooling unit. Could you make a video how to build a passive cooling unit for serveral of those in a row? I was thinking about some kind of aluminium plate.

[@FerralVideo]

These work VERY well used on a three-cell Lithium battery pack. The full battery voltage is at the full drive voltage of the light. Then, as the battery runs down, the light will gradually dim, giving you a handy indication that your battery's running low. The LED cutoff is just above the safe minimum voltage of a 3-cell pack, so even if you set it and forget it, it shouldn't over-discharge. Only complication is that you may need some way to cool the panel at full power/full charge, until the battery runs down a little. Fortunately though, you have 12v right there if you wanted to connect a fan and heat sink system ....

[@ALAPINO]

Seems like a decent low profile light panel to build up from. Too bad the pads seem to be quite small.

[@superbun277]

Warning: This video contains graphic scenes of LED array mutilation.

[@condew6103]

The mutilation does make one cringe, but very good information that the panel is 4 regions of LEDs all in parallel, and then the regions in series for about 12v. I like the redundancy such that one or two LEDs failing open should not appreciably affect light output or longevity. Failing short would probably blow the LED off the board with 5A thru the bad chip. The one aspect of discrete or surface mount panels that I don't like losing is repairability, but if the panel can suffer some failure and keep going, that helps a lot.

[@vaio232]

:(

[@acmefixer1]

Kind of a shame, ain't it!??!

[@FryGuyNS]

I got one 7" x 8.25" rated for 300 watts! WOW the light output! Needs a huge heatsink to run cool.

[@sonajero25]

very interesting presentation

[@Globetrottahh]

Nice find!

[@Elec-DIY]

LEDs on the cob..., run!

[@SpydersByte]

I'm glad that, with 21 likes and 1 comment, at least 23 people understood this reference :D

[@frankheijkamp3792]

That panel is indeed massive. Clive do you have any way of measuring the Color Rendering Index (CRI) of this thing?

[@licensetodrive9930]

YES! I have found my new front light for my ebike :D

[@keaganknapp2237]

There is a even higher power one on Ebay that I bought and it is rated at 200w and it is in the form of a large circle measuring about 160mm

[@electronicsNmore]

12 rows by 20 is 240 chips. Must have meant 28 across That's a huge COB. Great video!

[@ArlenMoulton2]

He said 28

[@VanFlicke]

I had to listen three times and still didn’t hear 28. Shrug. No big deal

[@TheComputec]

@@VanFlicke I think he said 20 to begin with but in later comments, after he murdered the first LED he did say 28.

[@yiravarga]

This is the first thing you’ve shown off that I’m really tempted to buy! It’s a very nice looking panel, and I got a lot of cool ideas for this. Could you do some more testing? Would it handle 300W for at least 200 milliseconds? Maybe 100W for 400 milliseconds? With heat sink of course, I never go without a heatsink.

[@RWBHere]

Very nice. Thanks BC.

[@AwsomeVids83]

I think I'm going to buy one right now.

[@Chickey]

Have two of these, one turned up with a single bad LED another had a chunk out of it which was a shame but got my money back so hey oh shall use them for some new lights i've planned still.

[@funkybobblehat]

Hello big Clive. Love your videos and in this one you mentioned that you would not run 70 Watts through this panel. I've just ordered one to play around with I was wondering what controller you might suggest 2 power one or more of these? What you need one controller per panel or could you get one controller to Power four or five of these. I am looking to keep temperatures down and figured this unit could help in that regard. Any help gratefully received. Regards

[@ElmerFuddGun]

12:35 - The current went up 10x when that section was shorted out. And that is with the reduced voltage... if it was being run with a higher voltage PS (not current regulated) the current would be very high and limited "by the wiring". Something to keep in mind when wiring it up.

[@fastbike175]

Thats a great pannel. How small could a regulator be built for this? Ive put together a rectifier for my wr450 lighting to be able to use LEDs. The single large pannel would make a very interesting replacement for the entire original headlight.

[@meowcula]

"excuse me rambling about, i'm just experimenting" umm... that's one reason why I watch you :D

[@fourzerofour7860]

Woohoo. Big LED light!

[@EFLO3D]

I bought four of these a while ago. Thinking of making a work light.

[@1kreature]

As a public service you should expose more of the wiring on the board and discover if it's safe to drill holes anywhere. Mounting these to a proper heatsink with good/firm pressure will be hard since they have no holes in middle. If it is safe to drill holes in a few locations inbetween the LEDs it would help.

[@jagboy69]

I think my welding table is about to get some new seriously bright lighting!

[@Karl_Kampfwagen]

Nice 👍 12 V solar array, to battery, to lighting, or a regulated 12 V supply would be BOSSSS

[@rafaeloda]

How the hell this channel wasn't in my life before?!?

[@iamdarkyoshi]

Your favourite 100w LEDs are being sold in COB form now, and they're perfectly even I got some for my garage, they haven't had any issues with dying rows or uneven leds after running them at 90w+ a day

[@urugulu1656]

m.ebay.de/itm/COB-LED-Panel-Lampe-Spotlicht-10W-30W-50W-70W-100W-120x36-220X120-200x10mm-/263642714031?nav=SEARCH

[@urugulu1656]

they are intrigingly cheap... less then 6 euros...

[@MegaMetinMetin]

Luke Den Hartog i find with leds they last forever but its the converter thats dies

[@stinkycheese804]

A "WHOLE" day? I've ran lots of 10W to 100W COB that lasted 100 hours before dies started dying... You're much better off running something like this at half power and that on a massive heatsink, or closer to 1/10th power if you prefer little to nothing heatsinking it.

[@cnerde]

Meaning 90+w every day all day... derp.

[@mevk1]

hot clothing iron is vice of knowledge -great tip!

[@willybee3056]

I heard that someone said, let there be light.. Was his first name Clive, too? Keep up the good work. ..

[@evghenim1955]

I’d really love some of there but in UV. Would work perfect for a small exposure box.

[@Moostery]

I wish PAR meters weren't so expensive. I would like to get a closer look at the spectrum coverage of that COB. It seems like a fun COB to wire up a ton of for an indoor grow light. Nice to see another post from ya, Clive.

[@youtubekillerxxl3878]

Moose 8

[@rub3nelmillor]

Might be late, but look for MIGRO youtube chanel. He did a good analysis on this one. Cheers

[@budandbean1]

Where do you suppose you might be able to get a heat sink for something this size? If I could figure out a lens and a way to keep it from overheating, this really could be a great little fog light.

[@jasondoe2596]

Very very neat! I wonder if I could find some "warm white" ones with known specs... (emission spectrum & CCT). I think you shouldn't underestimate the accumulated heat though, especially if not directly heat-sinked (or actively air-cooled). I don't think over 1A is realistic for 24/7 usage, if you care about its longevity. Then again, this thing is quite cheap for what it is.

[@amorphuc]

Seems like it could be part of a pretty nice portable "Trouble Light". Somehow regulate some 18650s with an on off switch?

[@TheComputec]

I really appreciate you sacrificing the panel in the pursuit of knowledge. Just a shame the manufacturers don't share that info on a schematics document. After all they can hardly keep it a secret given the price !! If this was needed for a critical use, such as an emergency illuminated information display it is handy to know how much illumination you lose if one led were to die. Maybe they just don't want to spend the money getting the design info translated into English? or they simply don't care what happens to them once they leave the sweatshop... erm I mean factory !

[@davelordy]

The colour temperature of these are around 6000K+ so they make good SAD lights.

[@christopherames5552]

Imagine going back in time late 1970's and you forget this board in you pocket.

[@dirtrusty7228]

Instant butterfly effect. WWIII, dogs and cats living together, mass hysteria!

[@AttilaAsztalos]

When you went to 5 amps, I had to instinctively squint. Which is utterly ridiculous; I'm still looking only at my monitor's dialed-down backlight...

[@leyasep5919]

that's true and it's a really fascinating psycho-visual behaviour : your brain "feels pain" from the contrast despite the lack of dangerous light. It makes you reconsider what pain is and how it works.

[@thedillestpickle]

I watch videos of people welding and it's the same thing. I've trained myself to know not to look at a welding arc and I instinctively look away.

[@heyidiot]

At five amps, Mr. Spock was freed of the parasite, but unfortunately, he is now quite blind.

[@dazzjh40]

Yep got to get me one of those.

[@DarronBirgenheier]

I'm going to install some of these LED light panels in my 1986-vintage motorhome to replace the 12V bulb-type fixtures that are in there now. I will be living in the motorhome full-time (in a static position) starting later today (hopefully!). A few years ago, I installed one in a shipping container house that runs from a PV array and a 200AH 12V AGM battery. I have been VERY impressed by it. It's cheap, and has very "soft" output because of the large area. The motorhome has ONLY 12VDC lighting, so unless I plug in a bunch of extension cords and put up 120VAC lighting, 12VDC is all I can do. Given that I'll eventually be off-grid with the motorhome, 12VDC is actually an advantage for me, as I can run all my lights directly from the PV-charged battery in the RV, without needing to have an inverter on when only lighting is needed. These panels can be easily dimmed, too, so they use just a tiny amount of power to put out plenty of light for most situations, but crank up the knob and they get HELLA bright!

[@bigclivedotcom]

There are loads of choices for 12V lighting these days. You can also convert just about any light to 12V.

[@konnorbowen5246]

Hey Clive. Have you seen the range of tools from Aldi? They have several things like £20 soldering stations and £15 rotary tools among other smaller things such as £3 helping hands and mini vices. Might be an interesting range of products for review and testing.

[@Beany2007FTW]

Konnor Bowen aye, I picked up one of the soldering stations. I'm sure the temperature is way out on then, but they do definitely adjust their output and the kit itself is fairly clean and straightforward.

[@Jkirk3279]

Aldi America must not carry that stuff.

[@kimsleep4111]

Sit back, and enjoy..unfortunately kids, the only thing burnt today is Clives image sensor in his camera.

[@maicod]

or his eyes :(

[@anderssorenson9998]

this would make a very nice arm light for bench work or the mother of all flashlights

[@mattburrows2615]

Anders Sorenson this would make a nice work/flood light but a Cree XHP70.2 would make a more efficient concentrated beam for a 4290 lumen flashlight and only use 30w.

[@deanwaters]

Sweet i have the same measuring tape Wilkos 0.99P tape

[@LazyBunnyKiera]

Got any pictures of these things lighting up a back yard or something? Due to how thin it is, i could thing of quite a few uses for such a light.

[@proyectosledar]

Woooow, I need that!!!

[@AlkDarksniper]

Proyectos LED ¡En cuánto lo tengas, yo veré ese video! Saludos amigo. -Un seguidor fiel (aunque nunca comento) jajajaja

[@eyeswideshut7732]

what for, air traffic control? 🙂

[@jorditribo94]

Saludos desde Bariloche!

[@Dannyvirk]

So glad you didn't 'TIG weld these', last time you did it was like watching someone beat up R2D2.

[@Woermelon_cat]

Bought this based on this Video great buy!

[@larrygall5831]

Looks like it would make a good under-hood light. Need a protective lens and a resistor though. Using 16 ga. wire with a fuse from the battery would be best.. using a switch like a door switch (button switch that's closed with button out).

[@randymerrell7953]

What would I need and what would it take to use this LED as home lighting? Are there drivers you could connect to home circuitry and be able to use this LED cob?

[@thekhiman1]

This is amazing, thanks for making this video. If I were to wire it directly to a 12v car battery, what would you recommend for a voltage regulator?

[@bigclivedotcom]

Simplest thing would be a resistor. By the look of what's being sold online some seem to rely on cable resistance to limit the current.

[@thedillestpickle]

@@bigclivedotcom Since you were attempting to destroy it anyways... It would have been interesting to see what unlimiting the current would have done. Does it have enough resistance to limit the current on it's own? I am looking at getting one of these for a solar application where energy will be limited. I don't want to use just a resistor which could use up half the power itself, so I will look further into how to limit the current.

[@thedillestpickle]

Mind you without spending more than 10 dollars if possible

[@lrastus6692]

Neat ... Looks like a lot of bang for yer buck (magic smoke included) . Putting one of those in a cheapo rip-off led work light (or even an old quartz halogen type) should make a dandy trouble light .

[@volvo09]

That would be a good way of making a cheap light quite effective. Driven at low power it would probably put out more light than the fixture already had, and stay cool. Still wonder if a real bridgelux or cree cob would be better... and the price is pretty similar. It is amazing how much more light / watt you get out of a "real" led, making you wonder why these exist. These unbranded ones are neat to play around with (i do have some) but they are truly super low end as far as light output goes and need to be cheap... factoring that into a price of more than $10 they are actually a ripoff when cobs that output like double the light for a few bucks more exist, and will actually last.

[@ast_rsk]

Well color me interested in this. What would it take to have a plug-in power supply with variable power for one (or two) of these?

[@JimNichols]

Ohhhhh that's is ferocious. ..

[@Zeratuhl]

Seeing this I immediately wanted to do a diy bulky flashlight with it, but having little experience in sourcing led drivers I'd love to know if someone has any suggestions for some kind of ~60W constant current driver I could use. Most things in that range on ebay appear to be either enormously bulky or they operate at much higher output voltages than this thing will accept. My thinking right now is that I'd like to essentially wrap up a handful of 18650 cells, a driver and then bolt those to the back of this panel, optionally with a heatsink in the middle and then arranging some sort of case or frame for it in the end.

[@pequodexpress]

I also just connected one of these COB panels to a bench power supply. Using a 5v-24v dimmer switch, I was able to click on 100% brightness without the light blinking , though I don't think this was the true 100% brightness, as my bench supply was putting out a max of only16.4v at 3.16 amps (maybe the max for my bench supply), which is only 51.8 watts. This panel should be rated somewhere between 70 watts to 100 watts. My question is what is the ideal DC power supply to get maximum wattage out of this panel? Should I stick with 12v and get something that can put out at least 7 amps, or should I go to 24 volts? I will always be running the light with an LED dimmer switch.

[@JWH3]

I would really like to see this panel on a thermal camera especially at higher loads and enough time to build temperature up.

[@metalrott324]

would be cool to make a large array of these for some growing lights.

[@christopherames5552]

Only Big Clive Exes can dislike his videos.

[@pequodexpress]

I have to make a choice between variable voltage supplies. Should I go for a 3v-12v 10 amp regulated power supply or a 9v-24v 5 amp power supply?

[@alloutofbubblegum8165]

I think this would be the perfect thing for people that are converting vans into campers. A nice warm white light that would not use that much power and keep the heat down on rather hot evenings.

Connecting this directly to the potential charging voltage if 14.4V would be very bad though.

[@TheModernVictorian]

I ordered two of these before you made this video, just coming back to use get your wisdom on the best way to power them. I wonder if it would be possible to use a constant voltage 12v 5A PSU to drive these.. Or if it would be better to use a constant currant driver due to them having no limiting..

[@bigclivedotcom]

If you have a stable 12V supply I'd suggest a simple resistor to limit the current to a level that gives decent light but keeps the current and heat down a bit from the full rating.