Thinking of building my own 7500lm worklight

I wan’t to have a new floodlight / construction light for DIY work around the house and garden.
It must be powerful enough for (inside) paint jobs at night.
It must be portable, but not for travel.
And it must be a cheap.

I have owned a couple of different flood lights with claims of 20W to 100W which just aren’t bright enough. Even the more expensive ones from the tool shop are not what I expected.

Now I’m thinking of building my own.
I wanted to share my thoughts before I start building it.
Maybe you guys have got some great ideas because I never really build anything like this.

I have a large 3D printer available and I still have some stuff in my garage (which makes it possible to build cheap, with probably some overkill parts).

I have an 1000 Wh 4P20S 26650 li-ion battery left from my ebike.
It has a couple of bad cells, but I will dismount is to make my own battery packs of 4P(arallel) and 3S(series) (10,8V nominal power and 12,6V fully charged).
That is 12 x 26650 cells in total, and I want to make 2 or 3 packs.
3600mAh for one cell, so 14400 mAh in total for 1 battery pack
Capable of about 80 Amps continues (because I will never use any over 10 Amps, heat will never be the problem in case of the battery)
This way the battery pack will be 104mm x 78mm and 650mm high (+ some packaging), and will weigh about 1 KG

I also have an unused 12V led-strip of 5 meters. (120 leds/m SMD 3528)
I will use this for my first test build, but I want to buy a more powerful led strip for my final build.

Was thinking of a 5 meter SMD 3528 led strip.
240 leds/m

I will wrap this around an aluminium tube with a diameter of 150 mm.
The tube will be about 120 mm high (at least) for the 5m led strip to fit.
This tube is very light weight and will spread the heat of the led strip a little.

The tube will sit an a 3D printed base plate.
And I will slide over a 200mm polycarbonate satin finished tube for defusing and softening the light.

I want to design a round housing for the battery pack that will fit inside the aluminium tube.
The top will also be 3D printed, and I will mount a Battery Management System and dimmer in the top.

Total height will be around 20 cm.
Total weight about 2 KG
I’ll make a hook on top
I’ll put a nut under it inside the housing to be able to mount it on a tri-pod

Will this work?
Do I need any cooling for the led strip?
Any other suggestions? Better led strips to use? Or other design features to make it better?

Of course you could always go bigger and better, but then it won’t be cheap anymore.
Any suggestions on other type of LED strip that could do the job better and won’t cost me a lot?

And I will use a 12V DC powersuply so I don’t think I need a led driver.
I could use a voltage stabaliser I supose.

If heat would be a problem I could mount a fan insite the aluminium tube and vent the air from the bottom to the top, but I don’t know if that would be enough.

I still have 2 stock CPU coolers at home from PC upgrades so that won’t be a problem.

But what kind of cob leds must I look for? What kind of brands, types, specifications? Do you have a link or site to start from?

For example: YUJILEDS® CRI 95+ 100W COB LED 3200K 5600K - 400H - 2pcs — YUJILEDS High CRI Webstore

Thanks, but those aren’t nearly around the $13 that Robin mentioned.

Many thanks!
Can I use this kind of driver to power them with my batteries?

€ 4,09 | 400W DC-DC Step-Up Boost Converter 8.5-50V To 10-60V 15A Constant Power Module Led Driver Voltage Charger Power

This is a constant current driver I supose. How do I regulate the power (amps) of these things?

Interesting, i’d like to know what you come up with!

I will use a battery management system for my batteries for sure for equal balanced dicharge and safe cut off of the cells.

Will look into de SPST Pot as well.

I’m looking at design options now as I want to be able to use it outside as well. It doesn’t have to be waterproof but must be able to work in mild rain.

I did a quick and dirty sketch. Measuring isn’t accurate.
I couldn’t let loose the idea of a lantern type of light. But maybe I should, and go for something entirely different.
But this way the it will be rain proof.

I think this design will be good for lightning up an entire room when placed in the center of the room.
The “glass” in this design will be the satin finished poly-carbonate from above. This emits 85% of the light and gives it a soft tone.
I’ll hope this will give less hard shadows.

The bottom part will probably be square instead of round because that will make it more easy to install the necessary buttons or displays.
The frame will be made out of 4 large M8 bolt threads where I can mount all the parts and can carry the weight.
Of course this will not be a slick and smooth design, but I don’t care, it only has to be functional.

I bought some stuff and I found some stuff.
Now waiting for delivery witch will probably take a month (with China shipping).

” Samsung SPHWHAHDNM251ZR3D2”:
CRI80 at 5000k
13196lm at 1,62A 52V

1200 watt DC DC CC CV buck converter

Display with amp meter

BMS for the battery

And I’ve found myself a heatsink laying on the shelf.
A Thermalake Big Typhoon.

Total BOM so far: 25 euro :partying_face:

I should be able to have 1,5 hour battery time at low power mode (1,62A), taking in account an 85% efficiency of the driver and 80% use of the total battery capacity.
With 2 or 3 battery packs that will be enough for me.
I will use a 200 Watt laptop charger when I need to use the light for a longer period of time.

At high power mode (turbo mode) I must limit the battery power to 20 Amps because of the limits of this driver.
I could build an 4S4P battery to eliminate this, but this would add 400 grams to the design…
The battery already weighs an 1200 gram in 3S4P.
With 4S4P that will be 1600 gram… :open_mouth: I think I don’t want that and just limit the power output to 20Amps…

Little update here.

The design is a lot different from the first design.
I decided to go for a 4S4P ( @16V ) 26650 battery which is quit large and heavy. And I wanted the battery to be inside the housing of the lamp, so it turned out a bit rough.
But I’m not going to build it for it looks, but for it’s purpuse.

First test look really well.

This is what it should look like when it’s finished, and what I’ve got right now.
The battery will be in a closed casing though.

This is my 1200W buck boost converter. I disassembled the CC trimmer and replaced them with two pot-meters.
One for inside the housing which will regulate the maximum current, and the other one will be mountad at the housing to function as a dimmer.

CV is set at a 52,2V,
Currents are limited to 4.5 AMPS which is 234 watt at the COB LED.
When you take in account the power loss from the buck converter I think it drains about 280 watts continuously from the battery

Everything fits nice in the 3D printed housing.
With the buck converters heatsink facing the side of the CPU cooler is get’s cooled by the same fan and it works really good.

I bought a diffuse lens of 120mm that will be mounted over the cob.

So far it works really well. When I measure the temperature of the mounting plate just beside the COB it doesn’t get any hotter then 25°C (77F).
The buck boost converter doesn’t heat up at all.
Still waiting for my battery management system from Ali Express before I can build the battery.