new and thick. LED and driver?

[activeviii]

Hello all,

Im new to all this LED and driver stuff. Im not electronically minded but i can follow instruction, Well most of the time:D.

Im trying to get my head around it all but 2 weeks of having items in my DX basket and still not sure if im reading it right so can i ask a few questions please.

I am trying to turn a 2 D cell maglite into a 12v LED light that will throw the beam as far as possible.

I know i need the LED and a driver.aspheric lens, on off switch and a jack socket for the 12V supply (lipo). i might try dimming once i have the basics.

Am i right in thinking that a 3-18v driver will work on any battery from 3v to 18v or am i reading it totally wrong and i should take up knitting and sell my solder station.

this is what i have in the basket.

SKU 26110
1*Cree 5W regulated power output
- Output current: 1.25A
- 16.8mm diameter base, 5.5mm overall depth
- Voltage: 3V-18V
- Fully regulated circuit design

SKU 2394
True Cree Q5 bin emitter (guaranteed by DX)- Cree Flux/Color BIN: Q5 WG
- 3.7V typical driving voltage
- Manufacturer Rated 228 Lumens at 1000mA input current:

• 350mA: 107~114lm
  
• 700mA: 171.2~182.4lm
  
• 1000mA: 214 ~ 228lm

- Premium "Star" connection board for heat dissipation and easy wiring and upgrading existing star Luxeon emitters



Not sure on the lens either to tell the truth. I think i have read to much and confused myself.

SKU 44653
Angle: 8~120 degree
- Diameter: 50mm
- Material: optical glass
- Light transmittance: 98%
- Compatible for LED spot light, flashlight, DIY LED light etc.

or this one

SKU 12834
Item: 50mm*18mm 2~80-Degree Glass Optics
Dimensions: 1.97 in x 1.97 in x 0.71 in
Weight: 1.59 oz


Sorry guys if i sound so thick. Once i have a basic understanding on the drivers and LED thing i hope i can stop sounding to thick. I doubt it though.

I have the lathe and metal so happy to spin the maglight down and make a pill, i think thats what you call it.


thank you so much of any help you can offer in getting this old mans brain working.

thank again and all the best
Phil.

 

[AnAppleSnail]

The driver will run on 12v. But depending on how it operates, it may be extremely inefficient at 12v and produce gobs of heat. For a first LED project that's ok. Make sure your heatsink safely touches the driver bits that get hot. You are overdriving the LED. watch for tint changes. Sudden angry blue means fast LED death. The tint may turn more blue over time.The mag reflector is pretty good for throw. If your aspheric lens won't focus in the mag, you may need a spacer to accommodate its focal length. Good luck!

 

[Gunner12]

2 NiMh D cells and a good boost circuit could also work well, higher voltage ≠ brighter light. The DX sku 25505 boost driver can be modified to a higher current by decreasing the sense resistor, and could give you similar output as the buck driver. Of course, the buck driver can also be modifies to give a higher current as well but the boost driver allows you to use normal batteries.

The stock Mag reflector is also decent for throw, and you won't end up with a lens sticking out the front of the light or headaches from trying to get the lens in focus. If you are using an aspherical lens, the Cree XR-E R2 on DX should give you a bit more throw then the Q5 version (higher flux bin). If you aren't using an aspherical lens, then the XP-E or XP-G would do well. The XP-G would usually give higher output, but a wider beam with less throw then the smaller die XP-E. You could go for the XR-E mod and the reflector. It'll give you a slightly ringy beam, but then you can also switch to the aspherical lens when you want to.

The aspherical lens works better with the Cree's XR series of LEDs due to the narrower emitting angle of the XR series compared to the XP series. A higher percentage of the light hits the lens with the XR series.

There are maglite heatsinks for sale in the Custom light B/S/T forum and they work well. Also make sure to get some thermal compound to ensure decent heat transfer from the LED to the heatsink. More thermal compound doesn't mean better thermal path. You want a really thin layer of thermal compound since the stuff is only meant to fill in the gaps between metal surface and aid thermal transfer.

:welcome:

 

[activeviii]

Thanks guys from helping :kiss:

The heat sink im not to worried about as i can make one out of aluminium. i have seen plans for one.:thumbsup:

Im going to change the LED to your suggestion of the Cree XR-E R2 on DX :thumbsup:

You where saying the the drive would have a lot of waste. what should i be looking for? similar pricing. im not tight honest, just lack of play funds at the moment.

I really an at a lose with it all. LED and resistor i can handle but all this driver, emitters and Chips really are a bit to much for my brain but i will try and learn as i go.

I will buy both lenes and see which will give the tighter beam.

Am i right in thinking that i came run the LED with the driver with any battery as long as its under 18volt. or am i missing something big time.

thanks again for all your help. i really do appreciate it.

All the best and thanks

Phil.

 

[activeviii]

2 NiMh D cells and a good boost circuit could also work well, higher voltage ≠ brighter light. The DX sku 25505 boost driver can be modified to a higher current by decreasing the sense resistor, and could give you similar output as the buck driver. Of course, the buck driver can also be modifies to give a higher current as well but the boost driver allows you to use normal batteries. This is way beyond what my capabilitys are. im stuck with off the shelf items. I need 12v as i would like a longer lamp time, 3 hours constant sometimes 6 hours. am i asking to much? i have no idea haha

The stock Mag reflector is also decent for throw, and you won't end up with a lens sticking out the front of the light or headaches from trying to get the lens in focus. If you are using an aspherical lens, the Cree XR-E R2 I have put a couple of these in my shopping basket and replaced the other one on DX should give you a bit more throw then the Q5 version (higher flux bin). If you aren't using an aspherical lens, then the XP-E or XP-G would do well. The XP-G would usually give higher output, but a wider beam with less throw then the smaller die XP-E. You could go for the XR-E mod and the reflector. It'll give you a slightly ringy beam, but then you can also switch to the aspherical lens when you want to.

The aspherical lens works better with the Cree's XR series of LEDs due to the narrower emitting angle of the XR series compared to the XP series. A higher percentage of the light hits the lens with the XR series.

There are maglite heatsinks for sale in the Custom light B/S/T forum and they work well. Also make sure to get some thermal compound to ensure decent heat transfer from the LED to the heatsink. More thermal compound doesn't mean better thermal path. You want a really thin layer of thermal compound since the stuff is only meant to fill in the gaps between metal surface and aid thermal transfer.

:welcome:

Thanks again


Phil.

 

[activeviii]

The driver will run on 12v. But depending on how it operates, it may be extremely inefficient at 12v and produce gobs of heat. For a first LED project that's ok. Make sure your heatsink safely touches the driver bits that get hot. You are overdriving the LED. watch for tint changes. Sudden angry blue means fast LED death. The tint may turn more blue over time.The mag reflector is pretty good for throw. If your aspheric lens won't focus in the mag, you may need a spacer to accommodate its focal length. Good luck!

Now you have me worried.haha.

What should i be looking for in drivers, off the shelf as there is no way i could modify a ready built one.

thanks again for all the help

kind regards

Phil

 

[Gunner12]

Higher voltage also doesn't mean longer runtime. What's the amp hour rating on the 12v battery? Also, wiring up the boost drive and the buck drive will be identical, except that one raises the input voltage to the LED's voltage, and another lower the input voltage to the LED's voltage. I prefer using normal batteries instead of specialized battery packs so if the batteries dies, I can always get new batteries easily. That is why I'm pushing you towards

Watts = Voltage X Current
Watt hours = Voltage x Amp Hours

Say I have a LED at 3w with a 75% efficient driver running off a battery at 3v and 10 Ah (around the same as 2 D cells, 1.5v per cell, 10 Ah per battery). As a note, good drives are more efficient then 75%.

So, the LED and driver will take, 3w/75% = 4w, 4w of power.
The batteries have, 3v x 10 Ah = 30 Wh of power stored.
So the light will run 30 Wh/4W = 7.5 hours (assuming the batteries stay at 3v till they are dead).

Realistically, you'll get anywhere from 3-8 hours to 50% depending on how the batteries perform. NiMh rechargeable batteries will perform better under higher loads then alkalines. The above calculations hold for any battery, LED, and driver combination (as long as it is DC) and should give a rough estimate of how long your light will last. Note, I am not an electrical engineer, I am a biomedical engineer. Much of this is from classes and what I picked up reading on the internet.

If you don't know the wattage to the LED, then this might help. White LEDs run from 3-4v depending on Brand, Mode, and current to the LED. 1000 mA = 1A. Personally I use 3.7v for the LED for a more conservative runtime estimate. So, a white LED at 600 mA will be, 3.7v x 0.6 A = 2.22 W.

For the drives your mentioned and I've also mentioned (the DX sku 25505 boost driver and the DX sku 26110 buck driver), there is one resistor on the driver called the "sense resistor", making this resistance lower will increase the current to the LED and making it higher will increase the current. On both of the drivers mentioned, there are posts about how to modify the sense resistor, but that requires small soldering and low resistance surface mounted resistors.

Generally drivers work more efficiently when the battery voltage is closer to the LED's voltage, so 3v would be closer to the LED's 3.7v then 12v. As a rule of thumb, boost drivers are also less efficient then buck drivers.

 

[turkeylord]

Don't mean to threadjack here, but it sounds like the OP got his question answered and I have a similar one...

Looking to replace a 3W Luxeon Star in an old Streamlight. I've been looking at datasheets, and it looks like the Vf on the Lux is 3.7V. The Nichia 219 I'd like to replace it with lists a 3.1V Vf. I assume that means I'll need a new driver? Any suggestions?

 

[Gunner12]

Depends on how the driver works, if it is a constant current driver, then you'll be fine. But if it's a constant voltage driver, then you might overdrive the LED. I'm not sure how you'll check that though. Most likely it's a constant current driver, since the same model of LEDs from the same company can have varying Vfs.

 

[turkeylord]

Thanks, I guess for $7.50 I'll have to just try it and find out. I don't like the Luxeon or the flashlight body that much anyway, so not much to lose. :)

 

[Gunner12]

If you have a set of resistors (5W or more rated power), you could test with 4 and 5 ohm resistors, if you don't have the right Resistance or rates power, you could wire up resistors in parallel until you reach the correct resistance and power rating. Just search up "resistors in parallel" if you forgot how to calculate the resistance of parallel resistors. Wire up the resistors and measure the voltage drop across the resistor, and then the current across the resistor. If the currents across both resistors are the same/similar, but the voltage drop is different, then the driver should be current controlled. Someone correct me if I'm wrong, I'm not a EE.

 

[turkeylord]

That's good advice, then I can just adjust the resistance to get the Vf required. :)

 

[Gunner12]

I was talking about replacing the LED with a dummy load (the resistor) and measuring how the driver reacts to the different resistances. If the current stays constant, then the driver should be a constant current source, aka the Vf would not matter (within reason).

 

[turkeylord]

Ok, I understand now. Initially I thought you meant in series as a voltage divider.