I'm thinking in make a homemade flashlight using an old flashlight case like this one

I'm thinking in make a homemade flashlight using an old flashlight case like this one:



I've already replaced the light bulb for 9led's from an old flashlight like this one





But in my homemade flashlight I have a case to 4 "D" batteries in series, but I can put 18650's instead but in series no, because the voltage would be to high, but if I put them in parallel? it would be a problem or dangerous?
later I will post here pics, thanks guys

here are the pics:

the leds





batteries holder




at the moment it holds 4x D batteries in series, but if I put on it 3x 18650 batteries in parallel it wouldn't be a problem, right?
thanks guys

9x 'micro-output' 5 mm. LEDs in such a case? My 1x CR123A light puts out more light than those 9 LEDs combined, and does so using less power.

A housing like that deserves a high-flux power LED, which (given the reflector size) doesn't have to be a tiny-emitter-surface one either. At least a Cree XM-L2, but perhaps an MK-R2, MT-G2 or something like that. For added effect, power with a set of 18650 or larger size Li-ions.

5 mm. white LEDs don't just have poor output in comparison, but also bad cooling and poor efficiency. Read: you burn through batteries for no good reason.

:welcome:

any number of 18650s in parallel would still be 4.2v, which is less than the nominal 6v of the 4xD cells that you are running now, so you are safe to use it. This is a good start and looks like a lot of fun, but with that much battery power, I do agree that a modern power LED would be more efficient than the 9 5mm ones.

thanks guys for your reply
I just made this, because I had this 9led "head" from an old flashlight and decide to make this just for fun
But, If I find a better led on ebay that consume less power and give more light I will upgrade my flashlight, of course
And the thing about the 18650s voltage in parallel it's not a problem because I just want 4.2v max but more run time, and I ask this because I know that 18650s in series is a bit dangerous :S
So I will use this in parallel
Can you guys tell me what to look for on ebay, to find a better led that consume less power and give me more light?
up to $10 +/- because I don't have a lot of money to spend in this experiment
thanks

anybody? :S

I am guessing that you might get something like 100 lumens from those 5mm leds. Probably less. The light is made of plastics. If you put in something that is a lot brighter, heat will soon become an issue and you need to take care of it. You also need a driver. Nothing that couldn't be done but it just takes some extra effort. You could have tried to replace the original bulb with a led bulb having the same base and voltage range but I guess that is too late now (and they wouldn't bee THAT bright anyway).

Regarding the use of 18650 batteries, if you are going to build a fixed pack, you should be good to go. If you are going to use separate 18650 cells and a battery holder, you should always make sure that the voltages are the same when you connect the batteries. I suggest that you use good quality batteries with protection circuits.

On the other hand, there are some 10000mAh and 12000mAh Ni-MH D-cells, too (at least in Battery Junction). If you want more runtime, I suggest that you consider them instead of 18650.

Four NiMH D cells, a Cree XP-E2, and a single AMC7135 driver. That would give you around 30 hours burn time, 100 lm, and minimal issues with heat. I'd bet this is way more output than you have with the existing 9-led light engine.

Four NiMH D cells, a Cree XP-E2, and a dual AMC7135 driver. That would give you around 15 hours burn time, 200 lm, and minor issues with heat.

Four NiMH D cells, a Cree XP-G2, and a triple AMC7135 driver. That would give you around 10 hours burn time, 300 lm, and manageable issues with heat.

Four NiMH D cells, a Cree XP-G2, and a quad AMC7135 driver. That would give you around 7.5 hours burn time, 400 lm, and potentially difficult issues with heat.

Replace the D cells with 18650's, you get about the same performance (though perhaps the output drops some approaching end of discharge). Much smaller and lighter, possibility of fitting more cells to improve burn time, but slightly higher risk fire, and usually requires different charger.

arierep60, you want a ~3W power LED that's soldered to a circuit board (pcb, common sizes are 16 mm, 20 mm. round or a star of some kind, with aluminium back for cooling). Runs into 3-5 US$ at sites like FastTech, DealeXtreme etc.

With a matching battery configuration (1x Li-ion, any number in parallel, or 3x NiMH), a simple series resistor does the job. Better is a dedicated driver that maintains a constant current within a specified voltage range (~3 US$ or so).

The rest is a matter of lumens/Watt, runtime, and physical construction.

so, an 3w led like this one is good enought right?

http://www.ebay.com/itm/CREE-XML-XM...843?pt=LH_DefaultDomain_0&hash=item5d474db673




thanks

Yup. Note:

1) Cree XM-L2 is basically the same, but with somewhat higher output than XM-L. Slightly harder to find, but shouldn't be much more expensive.
2) There's output bins (differing in lumens output @ the same current), and tints for these LEDs. Warm white, neutral white, cool white, etc. Make sure you know what you're getting, and that it is what you had in mind.
3) 3x a NiMH cells in series or a single Li-ion cell + resistor will power this fine. More mAh's (for example D cells) = more runtime. Add a driver board for different output modes and/or more accurate current control.

thank you

wow, you will get a nice flashlight Gez777
it's easy to make it with the driver too?
i don't know what kind of driver to buy or even how to instal it :S
cause if it was easy I will buy one too to build mine instead of having only the led

arierep60 said:

wow, you will get a nice flashlight Gez777
it's easy to make it with the driver too?
i don't know what kind of driver to buy or even how to instal it :S
cause if it was easy I will buy one too to build mine instead of having only the led

Click to expand...

The driver is pretty small so you would need to be careful soldering the LED points:



The parts came in at around:

battery holder $11 (if you want to go with unprotected 18650's)
Heatsink $3 - you could just us a spare GU10 household LED bulb heat sink if you have one.
LED $8 - that was for a XML, you can find XPG, etc a bit cheaper.
Driver $3 (you can find on Dealextreme or Kaidomain, fasttech etc - search for

4* AMC7135 2-Group 3/5 Modes LED Flashlight Driver (Nanjg 101-AK-A1)
you need to short out the pins as shown for High-Med-Low otherwise you get strobe and SOS too.

You will need some type of thermal paste to be the LED on and at least epoxy to mount driver

but I solder the led wires to the driver and then what? :S

you have 4 wires here:





i don't know if i can do this right

I did not take a photo of the front of my driver so I used a stock photo of the same driver to show LED soldering points.
so red wire on the stock photo is my green to LED(+) and black is my white to LED(-).The thicker black and Black/white
wires on the back of the driver you can see (in the photo you reposted) are the ones bringing battery power to driver, (+)
in middle and (-) on the edge. I hope the below photo makes things clearer
BTW I forgot to add that the White and Green wires are Teflon sleeved ones - for heat resistance, again eBay provides.
As regards difficulty, the hardest part is soldering the wires to the driver as the (+ and (-) tabs are very small.

Gez777 said:

battery holder $11 (if you want to go with unprotected 18650's)

Click to expand...

...Which you do not want to go with. If you do, you need to be extra careful every time you touch the batteries. Otherwise, one day you will be putting a charged battery and an empty battery in parallel, causing the empty one to be rapid charged (you forget to charge one battery, or you you charge 2 and put them back in place before removing the third one, etc. etc.). You asked about safety in your first post and this is the potential danger point in parallel li-ion. Go protected, be protected.

thanks Gez777 now I understand it
but what if I don't short the 2 pins on the circuit?
what modes I got?
or if I buy this one, I got 5 modes instead

http://www.ebay.com/itm/2-8-3A-5-Mode-LED-Driver-Dimmer-Circuit-Board-fur-2-7-4-2V-lithium-ion-Batteries-/270840497213?pt=DE_M%C3%B6bel_Wohnen_Lampen_Lichtzubeh%C3%B6r&hash=item3f0f5a043d

right?

Thanks Esko, I had been having second thoughts about that holder as the battery connections are poor, so got this instead from eBay:



l'll use protected 18650's in parallel in this, and with 4 off them the runtime will be phenomenal -I ran a test with one in the old holder and it lasted 8 hours
on 'Med' so with 4x on low, who knows, days maybe!

Arerep60, you could use ether driver, yours is 2.8a so will be a lot brighter on 'Hi'. My driver will give you five modes too (or 3 modes if you short the pins)
it will use less power on 'Hi as it is 1.4a so more suited (to me) for a flood lantern that will last a long time, the choice is yours.