Building a rechargeable LED flashlight.

[Biodegrade]

Hi everyone!
I will try to make my first post clear and concise. I work as a car mechanic in small independent shop. We bought this light because it seemed impressively bright: http://www.ebay.com/itm/Cordless-LE...Ion-1000-Lumen-Cliplight-114301-/400994266221
Turns out it has to be amongst the worst designed light for automotive repair, it is often too bright for close quarters, has a useless ans flimsy hook and no magnet. So I taped a magnet on it and...eventually forget it under a car to never see it again. My work partner lost one in a similar way too.

That is why I would like some help building a worklamp similar to a flashlight but with more flood capacity. Here are the characteristics I would like for it:
-At least 250 lumens
-Somewhat compact and lightweight
-Battery powered
-Rechargeable
-Runtime of at least 2 hours
-More of a flood style lighting than beam style
-Ideally no surface mount components

I did search the forum and did not find any similar helpful thread (there is one started which has 3 posts).
I am a novice in electronics but I know that I can make this with the help of google and hopefully you guys. In theory it seems like a pretty simple project but I get lost in all the parts! I am really unsure of what materials to use, what kind of LEDs and batteries and how to recharge these batteries. I am counting on your experience and knowledge for suggestions and ideas!

 

[cjdelphi]

You're in flashlight terroritory..

it's almost as bad as electronics, biggest grip with flashaholics is the low mode setting, either it's too bright or too dim, eg a fenix will probably be ideal for a mechanic on low..

To be honest, any flashlight will have the intensity but as you pointed out you need a low but not too low

www.fenixlight.com

I think their default low is ideal for close up inspection, once you hit around 100 lumens it's pretty useless unless you're walking home/searching

I've not seen anything with a magnet on it though, how's your diy skills? You could build one but housing it is tricky without a 3D printer

But a cheap fenix, you could probably use a fenix to prop up the car and you'd never know it been used afterwards, even an older cree led would suit your needs!

While you're looking look for an el cheapo ultrafire UV flashlight, might come in handy finding leaks ...

 

[(*steve*)]

look for some COB LEDs. They are flat and produce a very wide pattern of light (I deliberately did not use the word "beam").

Then buy an appropriate controller with the features you require and attach it to batteries with sufficient capacity to give you the run time you require.

Then build the whole thing around a baseball cap (possibly modified to remove or reshape the bill).

 

[Biodegrade]

You're in flashlight terroritory..

it's almost as bad as electronics, biggest grip with flashaholics is the low mode setting, either it's too bright or too dim, eg a fenix will probably be ideal for a mechanic on low..

To be honest, any flashlight will have the intensity but as you pointed out you need a low but not too low

www.fenixlight.com

I think their default low is ideal for close up inspection, once you hit around 100 lumens it's pretty useless unless you're walking home/searching

I've not seen anything with a magnet on it though, how's your diy skills? You could build one but housing it is tricky without a 3D printer

But a cheap fenix, you could probably use a fenix to prop up the car and you'd never know it been used afterwards, even an older cree led would suit your needs!

While you're looking look for an el cheapo ultrafire UV flashlight, might come in handy finding leaks ...

Well to be clear I am not looking for a flashlight, i have some fenix ones and they come in handy at times. My DIY skills are good enough to solder a few 1 watt 3 volts LED in parallel powered by some rechargeable batteries like cr-v3 or something like that and encase all of it in a pvc or aluminium tubing then epoxy a bunch of magnets on it. I want a portable low-cost(in case of breakage or loss) flood light for welding exhaust or changing a drive belt.

 

[Biodegrade]

look for some COB LEDs. They are flat and produce a very wide pattern of light (I deliberately did not use the word "beam").

Then buy an appropriate controller with the features you require and attach it to batteries with sufficient capacity to give you the run time you require.

Then build the whole thing around a baseball cap (possibly modified to remove or reshape the bill).

Thank you for your suggestions. I will look into chip on board LEDs. Not too sure what you mean by controller and why I would need it, I was thinking more about matching the LED voltage to the batteries and maybe dropping in a few resistors if needed.
A headlamp is somewhat useful in my line of work but they are often times where you need to shine light from one way look from another and get the tool in from where you can!

 

[(*steve*)]

See the resource we have on LEDs for the reason you need a controller.

 

[cjdelphi]

Thank you for your suggestions. I will look into chip on board LEDs. Not too sure what you mean by controller and why I would need it, I was thinking more about matching the LED voltage to the batteries and maybe dropping in a few resistors if needed.

You answered your own question, the resistor(s) is the *controller* unlike regular incan bulbs, the resistor is the filament, LEDs behave more like a battery, the more voltage/current you throw at it the more it sucks!

However unlike a battery an LED's foward voltage changes and so too the current, unless you plan on driving it at 1/3rd of it's current rating, current limiting is needed, for example i power a 12v RGB chip (10watts) using just transistors from a 9v power supply, so even if i gave it 9v directly, it's vf is low enough to be happy in winter it dims a little (heat affects diodes) and in the summer it's brighter!

Hence the need of a driver to keep the current constant

 

[Biodegrade]

See the resource we have on LEDs for the reason you need a controller.

I will need to read your article multiple times to really understand it all but I did get most of it. Very well written and clear by the way, thank you very much!
Since reading your resource (https://www.electronicspoint.com/resources/got-a-question-about-driving-leds.5/) I am thinking of maybe opting for a large array of low powered LEDs.
I am setback by my limited knowledge of LEDs and especially their brightness. The only brightness reference/comparison I have, are my flashlights lumens ratings. In clear I have no clue if I should use 3, 5, or 10 mm( and how much at how many mcd) LEDs over 1 watt high powered ones.
For example what is used in cheap stick and click style 3 LEDs like these?
http://www.amazon.com/Fulcrum-30010...d=1454865867&sr=1-4&keywords=round+led+lights
I guess what I really want is a nudge in the right direction so I dont have to experiment too much. If someone could tell me something like; ''Try taking X amount of these made4you brand LEDs and you should be fine'' I would really appreciate. If it all works out I could even write a guide/how-to with pictures for future novice inquirers.

 

[Biodegrade]

Well... I did use my very limited free time to stop at my local electronics store, and purchased a few overpriced components to experiment a bit. First I tried powering multiple 5mm ''high intensity'' LEDs similar to these ones; https://www.sparkfun.com/products/531.
Its just not going to be bright enough.
So then I tried powering a 1 watt LED and heatsinked it crudly. This yielded much better results while drawing a lot more current. I did power it from and old 3.7 V 700mah old cellphone battery and I think I fried the battery by doing that since it won't recharge now. It is quite bright but far from bright enough for what I want to do.
I will keep reading and learning to try and make this light, I have been looking into heatsinks, li-on/li-po batteries and their capacity, battery discharge rates, reflectors, lenses and much more. I also found a few videos on youtube and briefly looked at some circuit diagrams.
I think what I am trying to accomplish is fairly simple, probably too simple for people with proper and advance knowledge. Yet for a novice like me it is a hard and confusing project! I will keep you guys posted on my slow progress as I go along.

 

[(*steve*)]

Read the resource on LEDs.

You can't just connect a LED to a battery. It either won't work or you'll damage the LED, the battery, or both.

 

[Biodegrade]

Read the resource on LEDs.

You can't just connect a LED to a battery. It either won't work or you'll damage the LED, the battery, or both.

Yes I understand that and have already read the resource, after you suggested it last week.
I did my experiments using resistors as I do not have a driver/controller yet.
I will try powering 8x 1 watt LEDs from a 11.1 4000mah li-po battery trough a controller. Any help or suggestions on how to make the light is welcomed.

 

[(*steve*)]

There are a number of current limited buck regulators that could be used as controllers. These are cheap on eBay and have the advantage you can vary the output to suit your load. They require the load voltage to be lower than the battery voltage.

If you're using the LEDs in series (or going by my recommendation of a COB LED), you're likely to need either a quite high voltage battery or to use a boost converter.

I'll have a quick look on eBay for you and identify what sort of thing could be used.

 

[(*steve*)]

here is a boost converter http://m.ebay.com/itm/DC-DC-boost-c...-250W-10A-LED-Driver-/181940997254?nav=SEARCH

And here is a buck converter http://m.ebay.com/itm/DC-DC-Buck-Co...ge-Adjustable-Module-/191015464867?nav=SEARCH

And here is one that can do both: http://m.ebay.com/itm/DC-DC-Convert...-Down-Voltage-Module-/321347811892?nav=SEARCH

 

[Externet]

Come on ! .... To build that rechargeable flashlight you will need the rechargeable cell(s), the LED(s), the circuitry, the switch, the magnet, the hook, and the hardest, a proper housing.

Just buy one of these ----> http://www.aliexpress.com/wholesale...archText=led+flashlight+magnetic+rechargeable

and if you want, dismantle it to pieces, then you will have ALL the correct parts that will FIT together and you can build it again by yourself. AND will cost much less than the sum of parts ordered by separate with no wait time.