Monster 7,500 Lumens 100W LED Flashlight for under $10

I discovered that due to a lucky co-incidence of voltage and internal resistance, a 100W LED can be connected directly across the terminals of two 18V Nickel Cadmium power tool batteries. And that means you can build a 100 Watt (7,500 Lumens) flashlight for less than $10 (not including batteries).

Note: Don't try this with other battery types - you'll almost certainly fry the LED!

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Author Marty Vargo (3 months)
Polish the metal to a mirror finish and then use thermal paste in between
the metal and led and you will have great heat transfer.

Author darryl barton (5 months)
I especially appreciate your battery holder. That's clever.

Author PhantomAct (2 months)
Seems useless to build an LED that you can light up for a couple of
seconds... can you make it light up for longer?

Author metallitech (2 days)
I've heard that an LED uses less power for the same brightness if you give
it alternating current. Is this true?

Author David AE Levy (9 days)
lol this made my day, thank you!

Author MaxxHuey1 (1 month)
I am just guessing, you will need a 100 watt LED driver to regulate the
amount of current otherwise you will eventually burn out the LED anyway
even thought you have the correct limiting voltage. The is because as the
LED gets warmer, the resistance across the LED start to get lower allowing
more current to pass through, this vicious cycle goes on until the LED burn
out... Please correct me if I am wrong... :-)

Author thefotoman2010 (1 day)
Dass diese dämlichen knödel-englisch-Typen immer ihre halbe
Lebensgeschichte erzählen müssen. Kein Deutscher würde so viel erzählen.

Author Andreas Kötter (16 days)
Sure, the batteries are for free right? What? They cost 60$ each? Hmmm...
then this isn't 10 Bucks ...!!!

Author jimvandamme (1 month)
You won't get 20,000 hours out of your flashlight unless you carefully
control the heat and current of your LED. Then again, you are not going to
run it for that long anyhow. It's the internal resistance of the batteries
in series with the resistance of the LED that limits the current. Heftier
batteries would have less resistance and be worse for LED lifetime.

Author Arcadio Munoz (11 days)
Would this still work with 18V Li-Ion batteries from a cordless drill?

Author Jason Leo (25 days)
sorry but this video is complete shit. firstly how is it a lucky
co-incidence you can use 2 18v batterys? loads of batteries exist and
therefore it would be always possible to find 2 to work and secondly whats
with the fake title to get views? ryobi batteries are what £30 each so to
make this would cost £70 for yours or £30 using cheaper batteries. so no
you cant make this for $10 dollars because without batteries its half made

Author Loren Husky (22 days)
Could these be used to grow plants?

Author OfficialHardtechnoChannel (3 months)
Sorry Julian, but this is sensless since there is no current limitation in
the circuit. Even in short turn-on intervalls, the led can (and will) take
damage due to the hughe amount of current.

Author chillzwinter (1 day)
You could just solder 27 NiCd batteries together for $50. At 1000mah you'd
get 20 minutes continuous use - and closer to the exact voltage spec.

Author girlsdrinkfeck (2 days)
id use the biggest CPU heatsink i can buy

Author Nick C (15 days)
Maybe see if there's a CPU heat sink that is of equal size and can be
mounted to the back with thermal paste and a fan?! I'd guess this could
work for a few minutes or longer. There must be a way to cool it properly
or they wouldn't have produced it, so what is the application that you find
this in?

Author OlivierAstuces (3 months)
If I'm not wrong, when you touch the copper at the end, you are touching a
wire that supports a 36V 3A current. Does it hurt ?

Author D. Conn (8 hours)
off grid growers love u

Author nicholas cremato (1 month)
Next is to use an old magnifying glass as a lens and away we go! 

Author Captain Canuck (6 days)
Very clever're on to something.

Author J (13 days)
Nicads are not he way to go, I'd power it with nimh batteries or LIoN packs
with pulse modulation rather than resistance, which just wastes most of
your power as dissipated heat

Author Joseph Perrotta (1 month)
The sellers spec sheet says 32V to 34V. The combined full charged voltage
of a 18V battery is around 19-20Volts. That being the case you would be
pumping at least 36 to 40Volts into this LED How long do you think it will
last before you burn it out?
It may work well for a few seconds give it 10 minutes with a 36V ebike
charger attached to maintain the voltage. See what your results are then!

Author BlancGivre (1 month)
I wonder, what are these 100W LED normally used for? Car headlights?

Author Jacob (10 days)
how are you able to touch the leads without getting shocked?

Author Steven Marks (13 days)
just buy a cree led flash light..!! about $30, 10,000 lumens, and doesn't
look like a suitcase

Author ЭДИК РУСИН (2 months)
с таким охлаждением сгорит за 10с. проверено!

Author superfinster (17 days)
And the whole unit fits neatly inside a GIANT'S pocket..........!!
Seems like a complete waste of time, money and effort and you might as well
just buy a great quality HAND HELD torch. ;)

Author Fabian Feilcke (3 months)
Not particulary suprising. Batteries are a power source rather than a
voltage or current source. You simply cannot draw more than a certain
wattage from it, as the internal resistance rises with the current.
So as long the maximum power the battery can supply is lower than the LEDs
Ptot there won't be any issues with the LED.

The problem is that if you use this kind of current limitation, a
significant part of the power is heating up the batteries rather than
producing light. 

Author Louis Riddle (21 day)
did anyone say how long these ryobi batteries would last?

Author MonaichFother (16 days)
WTH on Ebay UK now > Osram HLX 64663 36v 400w EVD Lamp / Bulb

Author liquidthex (2 months)
Under $10!
Except the wood
...twin 18v battery packs...
all just sitting around my garage (carport?) :)

Cool video anyways! enjoyed it

Author Ride84XL (1 month)
Best thing to drive this would be to build a constant current power souce.
For these power levels it would only cost a few dollars extra. A good thing
would also be to use a CPU cooler for a computer to cool the LED.

But that wont be as simple as this one - of course. I like how it just
flashed out the camera :)

Author Larkhill21 (21 day)
Nice ideas on the battery pack, but maybe attaching the heat sink to the
wood is worth stating that its only to used for a short time.

Author александр сергеевич (1 month)
сгорит так нахуй диод

Author Mihael Tominšek (1 month)
What the hack you've been thinking about to point 100W LED directly to
camcorder. I was thinking, he will move it aside right. No, he will just
plugit... o man. You've been lucky. But still camera may produce dead
pixels very soon.

Author Justin Steer (1 month)
Would be far better to limit the current correctly with a resistor allowing
longer use and longer life of the led. Also if you cut lots of slits into
the metal, you could easily increase the surface area of your heatsink, and
therefore its efficiecy. However this is no flashlight the word flashlight
implies a portable handheld device .... this is not :) Nice though.

Author Charagrin (3 months)
I am trying to figure out how you got 40 volts out of 2 18 volt batteries
using a inline connection, since creating an in-line connection just adds
the AH together and does not "double the voltage." The crossflow of each
battery is still capped at 18 volts as that is what they allow to pass
through them, just like how flashlights can have multiple batteries stacked
inside and yet still operate at 1.5V for example assuming normal household

I understand the difference between series and parallel connections, but in
practice if I stack 3 AA batteries in a line I still only draw 1.5V
according to my 3 different made testers. SO I am just trying to understand
how the voltage magically doubles despite the battery itself being designed
to only let so much voltage through.

Author Johnny Truong (1 month)
hahahaha That made me laugh so hard with the LED in the lens of the camera.

Author Shorty15c4007 (2 months)
3:30 You just nuked yourself. 

Author Craig Nehring (1 month)
Is there a lower voltage sweet spot that will illuminate that 100 watt LED
but will not generate as much heat and at a reduced lumen output?

Author Pat P (1 month)
area lamps like that would come in really handy during power outages.

Author Milo Tidwell (1 month)
A lot of HP Printer power supplies are 34 Volts as well.

Author fromnewark (1 month)
You didn't measure the current or voltage. My guess is those batteries were
putting out a lot more than 100W

Author Jared Connell (8 months)
cool video, I don't think the title is quite fair though because the
batteries alone cost more than that. I understand that you can use them
for other purposes but I don't think that if you mad this to use regularly
you aren't going to want to take the batteries out of your drill all the
time. I also wish you would've done something about a reflector and
lense, switch, heatsink, etc to make it more usable because I want to make
one to acutally use frequently and would like an example. 

Author Chris S (1 month)
Was für ein Voll Iddi schrottet seine Cam schier mit dem doofen LED Chip
lool dafür gibts alein schon nen Daumen Hoch hahahahaha

Author IIGrayfoxII (3 months)
You really should use an LED driver to control the current.

I have a 10W LED spotlight.

It has a 12v battery to power the LED and it can power the LED if i decided
to hook it up directly.
But the point of an LED Driver is the control the current the LED gets.

Author Piramerd Arete (2 months)
China invests hundreds of billions of dollars each year in research for
making things affordable and practical. Today China not only make things
for the world, but also started to design new ideas - A BBC documentary.
Thank you China!

Author RICHLES01 (1 month)
The 3000ma is more important than voltage. You need a current regulator

Author taylorID1 (2 months)
Twin & earth mains? Forgive this American for not speaking "English" but
that looks like our 14-2 UF except color coded red/green vs black/white. Is
that wire in common use for residential indoor or outdoor application in
the UK (assuming that's where u are)? With its moulded ground, that would
be used underground here in the US

Author Jefferson Asejo (3 months)
its hard to carry your flashlight because it is very big

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