# Help building a LED flashlight



## thumpergirl (Apr 23, 2014)

Hello all. Newbie here. My needs are simple but specific:


must run on a 10 pack of lithium batteries for at least one night (9 hours, preferably more - up to 15). I think lithium batteries are 1.5V, so that's a 15V power supply.
2 pin connector attached to the light instead of a switch
brighter is better, but not so bright that it runs the batteries down too fast.
it has no switch, it turns on and off when you plug in the battery pack
it is very lightweight, and very dependable
it is waterproof ( i suppose this is what silicone is for)



So, this is kind of last minute because I thought I could purchase one, but I probably can't. I need to know how to make one. I realize I've not contributed to this forum, so I'm thanking you in advance for your help. Hoping I can get this put together in a couple of weeks!


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## thumpergirl (Apr 24, 2014)

I think I should state my request more clearly. I'm looking for someone to help me identify what parts I need, and where to purchase them. I don't know what kind of led driver I need, or led emitter and reflector with wire leads, and the parts for the 2 pin connector. There are too many choices and I don't know heads from tails yet.


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## thumpergirl (Apr 24, 2014)

There's the threaded 2pin connector on the tail end that replaces the switch.






Thanks for any input.


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## RetroTechie (Apr 24, 2014)

A diving light might be a better bet than a 'generic' waterproof flashlight. :thinking: Especially when that paddling is in salt water.


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## zs&tas (Apr 24, 2014)

i think you should just look for a good light that is built to withstand abuse, it will always be better built than that. FYI a basic light i have , olight m20s takes two cr123 lithiums ( they are 3v each ) and runs on the 115 lumen setting for 9 hrs. has a lower and higher setting too.


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## thumpergirl (Apr 25, 2014)

Those are great suggestions, and ones that I will consider for the future. Right now, my time is very limited and my hull is set up to accept the light detailed above. No switches, no settings, etc... The mount is set up to hold that size case. Basically, my best bet right now is to identify those parts and build another. 

The case is an ultrafire 503b.

I don't know if I need to purchase the led emitter and reflector seperately, or as a single unit with lead wires. I also don't know how to find the right driver, and where to get the parts for the 2 pin plug. 

If anyone can steer me in the right direction, I'd appreciate it.

Here is a nice looking, inexpensive light that maybe I could start with and modify. Have no idea what to even call the 2 pin connector wire at the end. Help please! Running out of time. My teammates left me which has me racing in a solo boat and trying to outfit it last minute. Usually I don't wait this long to deal with these things. 

http://www.alldaymall.com/review/product/list/id/31/category/47/


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## RepProdigious (Apr 25, 2014)

So let me see if i can get this right; You have a P60 unit (the module that holds the led light), you have a big a$$ battery pack of questionable voltage (please double check that) and then you have an old flash-light body where wires meet and you somehow ended up with some form of drivers but it doesnt hold any batteries.... Does that sound about right?

If so buy something like this;

http://www.solarforceflashlight-sales.com/product_detail.php?t=RB&s=29&id=30

It will run on anything between 4-18 volts. Its got the needed driver stuff built-in, just pull off the big spring thats on there (it should just be snapped in place) and solder the negative wire to where the big spring used to touch the brass. The little spring on the tail-end of the unit is where the positive end of you battery pack goes so you might want to de-solder that or connect your positive wire to that in some other fashion.


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## thumpergirl (Apr 25, 2014)

Yes, I am sure about the battery pack. It's got 10 AA lithiums in there. 


would you happen to know where the find the fittings for 2 pin connector at the bottom? I don't know how to find parts like that that will fit the threads in the case.


(Thank you!!!)


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## AnAppleSnail (Apr 25, 2014)

I suggest that you get at least a quality 'dropin' (Light module). The Solarforce L2P is a hard-anodized "P60" host. These are a group of flashlights designed around a particular light module size. Buying a Solarforce L2P host would give you a metal tube with a tailcap switch on one end and a P60 head on the other end.

The dropin (light module) is the part in you pictures that says R5. That is, the reflector, the LED, and a driver inside the metal cup they sit in. Your existing WF50-whatever host will take a P60 dropin and work fairly well. Please check the condition of the O-rings, and seal any penetrations you make (For your power wires, for example). While the dropin will work ok in bad conditions, it's unhealthy for the electronics when the chips get wet.

A dropin will run on power within its rated input voltage, and the LED will run happily. Be careful about getting ones with modes - They may change from bright to dim or strobing modes if power is momentarily interrupted. That may be a good thing, if you could get away with less light at some times.

I suggest a 1-mode or 3-mode dropin with about 100-300 lumens and a reflector similar to your Ultrafire. "Orange Peel" is a reflector that has ripples, instead of mirror-smooth curved parabola. They give a decent compromise between high range and ringy beam, and short range with smooth light patterns.


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## mcnair55 (Apr 25, 2014)

Save yourself the bother nip into a decent outdoor shop and buy a headlight the type favoured by cavers as they are always in water.They run for hours and have good levels of brightness.


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## thumpergirl (Apr 25, 2014)

mcnair55 said:


> Save yourself the bother nip into a decent outdoor shop and buy a headlight the type favoured by cavers as they are always in water.They run for hours and have good levels of brightness.



Excellent suggestion, but I already have a great headlamp and I use that as well. I have a 21' hull and the bow light needs to be up at the bow. So the headlamp is a great backup, but it's about 11' shy of the bow, and can't stay on for long enough. This needs to run off an external battery pack, 15V, no dimmers/switches, and run for about 12 hours without needing a battery change. It's a pretty specific configuration. Unless there is a light out there that meets the exact criteria mentioned above, I'll have to build one.


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## thumpergirl (Apr 25, 2014)

> The dropin (light module) is the part in you pictures that says R5. That is, the reflector, the LED, and a driver inside the metal cup they sit in. Your existing WF50-whatever host will take a P60 dropin and work fairly well. Please check the condition of the O-rings, and seal any penetrations you make (For your power wires, for example). While the dropin will work ok in bad conditions, it's unhealthy for the electronics when the chips get wet. A dropin will run on power within its rated input voltage, and the LED will run happily. Be careful about getting ones with modes - They may change from bright to dim or strobing modes if power is momentarily interrupted. That may be a good thing, if you could get away with less light at some times.







if you know of good places to purchase these items, i'm all ears. er, eyes.


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## mcnair55 (Apr 25, 2014)

thumpergirl said:


> Excellent suggestion, but I already have a great headlamp and I use that as well. I have a 21' hull and the bow light needs to be up at the bow. So the headlamp is a great backup, but it's about 11' shy of the bow, and can't stay on for long enough. This needs to run off an external battery pack, 15V, no dimmers/switches, and run for about 12 hours without needing a battery change. It's a pretty specific configuration. Unless there is a light out there that meets the exact criteria mentioned above, I'll have to build one.



I have just done a quick search and there are plenty of lights out there specially made for night paddling,have a look it may help your build or adapt something already on the market.


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## thumpergirl (Apr 25, 2014)

mcnair55 said:


> I have just done a quick search and there are plenty of lights out there specially made for night paddling,have a look it may help your build or adapt something already on the market.



Thank you for the suggestion. I have spent a lot of time searching for paddling lights prior to posting on this forum. Most of them aren't made for the low visibility, high run time need that I have. I am not adept enough to spend a lot of money on a light and then try to modify it. Also, my hull is specifically set up to receive the above mentioned specifics: a p60 host, with a 2 pin connector. Anything short of that won't work for me right.

If during your search you happened to come across something that meets the criteria, please post it.


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## thumpergirl (Apr 25, 2014)

I'm finding it difficult to find a p60 drop in around 100 lumens (under 200 for sure) that accepts up to 15V with a smooth reflector. If anyone comes across that, please post a link for me!


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## AnAppleSnail (Apr 25, 2014)

thumpergirl said:


> awesome piece of information, thank you. that makes sense. trying to figure all of this out in my limited amount of available time before the race is very challenging.


We toss around all kinds of TLAs (Three Letter Abbreviations) that can get overwhelming. "A P60 L2P is a great host to replace your WF501B XP-G R5 OP Reflector, unless you need a D26-compatible WolfEyes host." What?

The trouble with your project will be identifying what has gone bad, or replacing the whole thing. Many reflectors screw on interchangeably. But if they don't, getting good optical aim will be TOUGH.

If you can match the LED and the reflector type, you will get pretty close to your picked beam pattern. If you post a focused picture of the LED (Which is 'probably' a Cree XP-G, R4 brightness bin) we can be sure for you. Same for the reflector's inner surface (Tough photo to get).



> in the pictures of the light i have, it appears the driver is seperate. so maybe he did not buy a drop in, and instead bought the driver separate for some reason. does that seem like a reasonable statement?



It sure is. The driver is some group of circuits - If the battery input is not VERY close to 3.6v, it will need some chips and bits, inductors and resistors and capacitors, to work. Wherever you see those, that's your driver.



> so if i buy a 'drop in' it already contains the driver? modes will not be good for me. so it seems the drop in will dictate if there are modes. basically, the drop in is everything you need for the flashlight, sans the power source?


It does already contain the dropin. What you usually get is a sandwich. From the outside, it looks like a cylinder with a reflector on one end and a metal body on the other, about 3cm long (And about 2.54cm wide, incidentally).

From the inside it looks like this:
[|DC
[ is the metal base the whole thing sits in. This usually slides into the front of the P60 host. The whole dropin is held in by the screw-on 'head' of the flashlight. It can be a shallow pan, or a big heat-transferring metal body.

| is the driver board. It has chips and things on it. It has a center contact point for the (+) of the battery, and a ring contact area around the perimeter for the (-). These touch the front contact spring (+) and the body of the light (-). You can solder to these board pads.

D is the LED board. There are two wires coming from the Driver output. You can usually switch out the LED board pretty easily; most P60 dropins have a 20mm LED 'star' you can pretty easily move. Use thermal goo to give good thermal transfer.

C is the reflector. It sits over the LED, held centered somehow. It often screws on, and you may have to slightly unscrew it for perfect focus. "Perfect Focus" means the beam looks great and reaches fully without dark holes in the center hot spot. You will also see that the whole reflector looks 'yellow' with the LED off and the light far away from your eyes and pointed straight at you. The reflectors with matched attaching methods (Screw-on to screw-on) are interchangeable.



> the reflector i have now was chosen specifically by an electrical engineer who is also an ultramarathon paddler who competes in this race, so i think he's chosen the right tool for the job. i just wish i knew the specifics of the reflector. it's smooth, and it's a compromise between a narrow beam and just enough to see what's on your left and right in the river at night.


That sounds like a "Light Orange Peel" or a "Smooth" reflector. An XP-G in a smooth reflector gives a PRETTY beam.



> so if purchase an ultrafire case, i will have to purchase a drop-in light module, pop off the screw thing, find the pieces that thread into the bottom for the 2pin connector, and solder some wires in there. i guess once I have all the parts I can post and ask what gets soldered where.


Probably so. I am reluctant to guess without having tested to see what broke. Can you check for continuity, voltage, and current where those things belong, to isolate what's broken?

Lighthound.com has a lot of these things, as do illuminationsupply.com.


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## PCC (Apr 25, 2014)

thumpergirl said:


> My needs are simple but specific:
> 
> 
> must run on a 10 pack of lithium batteries for at least one night (9 hours, preferably more - up to 15). I think lithium batteries are 1.5V, so that's a 15V power supply.
> ...




In order as asked:
*10 lithium AAs? In series you should get around 15 or 16V.
*How bright is bright enough?
*Using the plug to turn it on isn't the best way to keep things waterproof nor corrosion resistant. A properly sealed switch is the way to go.
*Simple is better
*Anything can be made waterproof. This adds weight, though, and makes things harder to repair down the road.

My thoughts: if you need something quickly then get a properly made bicycle light like the Niteye B10. It has multiple modes and the dimmest mode gives you 64 hours from a fully charged battery pack. Use the next higher mode for more light and shorter run times (600lumens for about 6hours, 200lumens for about 15hours, 50lumens for about 64hours, manufacturer's specs). While this may not be completely waterproof it may suit your needs and can probably be made to work. The power connections are O-ring sealed. The battery pack itself might need to be placed into a sealed container to keep it safe.

Alternatively, you can probably get something cobbled together using a Sandwich Shoppe SOB500 driver, which will give you roughly 200 lumens of output using an XM-L2 and the amount of time it stays on is determined by the battery pack used. I'd go with a Li-Ion battery instead of lithium AAs because it'll have a higher power density, be lighter as a result, and be rechargeable, saving you money in the long run.


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## thumpergirl (Apr 25, 2014)

AnAppleSnail - Thank you so much for your patience and explanations. I know the questions can seem irritating to someone who knows what they're doing. So, thank you. <img src="http://www.candlepowerforums.com/vb/images/smilies/smile.gif" border="0" alt="" title="Smile" smilieid="1" class="inlineimg"><br>
     <br>
<br>
                <br>
The light that I have still works - the problem is that I don't trust it. It got a lot of salt water in it and there is quite a bit of corrosion. Also, the reflector is rusted. So what used to be a smooth reflector now has orange rust pits in it.A light failure will cost me the race.<br>
<br><br><br>
<br>
Somebody asked if I was sure about the batteries. Can't remember where it was, but yes I have a 10pack of lithium's wired in series to give ~15V.<br>
<br><br>


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## thumpergirl (Apr 25, 2014)

PCC said:


> [/LIST]
> In order as asked:
> *10 lithium AAs? In series you should get around 15 or 16V.
> *How bright is bright enough?
> ...




PCC, Thanks!!!


> In order as asked:
> *10 lithium AAs? In series you should get around 15 or 16V.
> *How bright is bright enough?
> *Using the plug to turn it on isn't the best way to keep things waterproof nor corrosion resistant. A properly sealed switch is the way to go.
> ...



*10 lithium AAs, yes. Wired in series providing ~16+V. Need a drop in accommodating up 18V.
*Bright enough would probably be around 120 lumens. Enough to see, but little enough to go a long way on a battery pack.
*Understand about the plug, but gotta have it. Can't reach the switch, the light is 11' feet in front of me. Details are boring, but I gotta have the 2 pin connector at the tail end right now.
*Simple is better, agree. 
*Waterproof, that's what silicone was made for!!! 


So, regarding the Sandwich Shoppe SOB500 driver, about how long you think that would last on a 10 pack of lithiums? I can't go rechargeable. I can't recharge during the race even though it saves money in the long run. If this were for more uses, I would spend the money on rechargeables.


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## thumpergirl (Apr 25, 2014)

I forgot to mention, I also want reverse polarity protection! Will most drop in's supply that?


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## TEEJ (Apr 25, 2014)

10 disposable lithium ion (Energizer, etc) at 1.5 v each would produce ~ 15 volts, and low amps.

It is very very unlikely that the set up you now run is running at that voltage....and, the AA's are probably in parallel, or, perhaps half are parallel, etc. (In series multiplies the voltage but not run-time)

If 5 were in series, that would get you ~ 7.5 volts, closer to the working voltage of some LED's you might be using (Most require 3.7 - 4.2, or, double that to get 7.4 - 8.4 etc.)

The other five could be in a parallel arrangement to increase run time. 


Use a multimeter to see what the output is for your current set-up is, to confirm what it is you're trying to replicate. If you have a one-of set-up with an unusual LED etc...this is the time to confirm it.



And, some drop ins will have reverse polarity protection....not all.


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## thumpergirl (Apr 25, 2014)

pinky swear this is running on 10 pack series AA lithium. I ran this setup last year during the race for 71 hours. Well, the race was 71 hours. The light was only on during the dark hours of that. The guy who made the light has engineering voodoo. He apparently did not by a drop in, he picked up the right parts and put them all together himself. I made the battery packs myself, so I'm not guessing as to what they might be.

As far as 5 running in series with another 5 running in series, doable, but my boxes are not built for that. My battery boxes are just big enough to hold a 10pack, and they're already built. So I have to make this work with the 10packs. The packs are putting out 16.27V according to my multimeter. 

Ideas? I will probably have to run 210 lumens at a minimum for a drop in. That's the lowest I've seen up to 18V. I don't know how long that will last.

Oh, how do I know for sure if the drop-in has reverse polarity protection? I've not seen it advertised anywhere. 

I'm sure it doesn't work this way, so somebody correct me. If I can run 100 lumens for 12 hours, does than mean that 200 lumens would run on the same voltage / battery pack for 6 hours? I don't think that's the case, but the hell if I know.  Anyway, if that does somehow magically prove to be true, then a 210 lumen drop-in won't be sufficient.


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## wjv (Apr 25, 2014)

thumpergirl said:


> Yes, I am sure about the battery pack. It's got 10 AA lithiums in there.




Doesn't meant it's 15 volts.

You could have 5 sets of 2 batteries each in parallel for 7.5 volts, or 2 sets of 5 batteries each in parallel for 3 volts.



thumpergirl said:


> The packs are putting out 16.27V according to my multimeter.



OK

Never mind.

It could be hard finding something that takes that voltage :shrug:


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## DIWdiver (Apr 25, 2014)

Yes, you are right that if a battery will run a 100 lm light for 12 hours, it should run a 200 lm light for only 6 hours. That's assuming the two lights are equal efficiency and efficacy (proper jargon to keep the techies happy).

But an Energizer Ultimate Lithium cell is around 3000 mAH, at 1.5V, so that's a total of 4.5 W-H (that's Watt-Hours). Ten of them would give you 45 W-H. A decent LED outputting 100 lm only consumes about 1W, so the battery pack should be able to run it for 45 hours (assuming a 100% efficient driver). If the driver is only 80% efficient, which is quite easy to do, you should still be able to get 36 hours run time. Or 18 hours at 200 lm, or 12 hours at 300 lm.

Some dropins can be modified to change the output. Going to lower output should make it more efficient. What dropins are you looking at?

For help with waterproof lights, you should be in the Special Applications Lighting -> Dive Lighting sub-forum. There's a sticky there that discusses where to get just about anything you'd need, including the cable gland (that threaded thing where the wire goes into the case). The one thing you may not find there is the two-pin connector. That looks like something I used to see in 80-s vintage Volkswagens my dad used to repair.


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## jabe1 (Apr 25, 2014)

I think you should try contacting members Nailbender, or vinhnguyen54. Either one could probably build a drop-in to meet your needs. Then you can concentrate on the bi-pin connector, and/or switch assembly.


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## RepProdigious (Apr 26, 2014)

thumpergirl said:


> I'm finding it difficult to find a p60 drop in around 100 lumens (under 200 for sure) that accepts up to 15V with a smooth reflector. If anyone comes across that, please post a link for me!



Scroll up a bit, thats exactly what i linked you earlier.


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## Supernatural (Apr 26, 2014)

RepProdigious said:


> Scroll up a bit, thats exactly what i linked you earlier.



I think she is questioning if that Solarforce dropin you linked will provide the required 9-15 hours of runtime she needs. I don't think she has a problem with the brightness as long as she can get the required runtime. If someone knows the current draw of that dropin we can do the math. I'm sure some of you can make educated guesses. Of course you'd also have to know how much is being lost when the dropin/converter has to step the voltage down from 16+ volts to the 3+ volt the LED's operate at. Am I the only one who thinks setting up those 10 AA battery pack in series so it puts out 16+ volts is _REALLY _strange? Wouldn't stepping down the voltage that much waste a *LOT *of energy in the process?

Oh wait, DIWdiver already did the math!

Mind telling us where this race is? Got a link? Can we watch in online?


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## Supernatural (Apr 26, 2014)

Hey I was wondering since the light is 11' away from her, is there any way to get some sort of remote pressure switch to extend that far?

I'm talking about something like this. I have no idea if that particular one will fit the p60 host.

I just remembered she has that 2 pin connector to her power pack, so I guess it would have to be set up in some other way to turn her power pack on and off.


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## DUQ (Apr 26, 2014)

My suggestion would to be to keep it simple and buy a light already build.

Take a look at *Pelican Nemo 2010n* Great runtime, water proof and 100 Lumens.

http://www.pelican.com/lights_detail.php?recordID=2010N


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## jabe1 (Apr 26, 2014)

The Solarforce drop-in is too bright, without the needed runtime (3 nights. the race is 71 hrs long). The Pelican can't be operated from 11' away.

Yes, she needs a switch on her battery pack, or inline on the power cord.


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## DIWdiver (Apr 26, 2014)

The 2-pin connector appears to be a standard SAE 2-pin connector common in automotive use, and readily available with wires attached. The one you have is unusual in that it has a sheath over the two wires, which would make it seal better in a cable gland, which is normally intended for cables with a round sheath. That's easily rectified with some silicone.

So it looks like what you need is:
UltraFire 503B body (or similar).
200 lm or less P6 dropin with 18V input capability (see my link in your other thread)
Cable gland (see sticky in Special Application Lighting -> Dive Lighting sub-forum )
SAE 2-pin connector with wires (google "SAE 2-pin")
Silicone or similar. (see sticky in Special Application Lighting -> Dive Lighting sub-forum )
Someone to assemble and test the unit (maybe).

I could build this for you, as could a number of others on the forum. PM me if you want to discuss details.


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## thumpergirl (Apr 27, 2014)

Supernatural said:


> Mind telling us where this race is? Got a link? Can we watch in online?



Late reply, sorry. I was out training all weekend. The race is called the Texas Water Safari, http://www.texaswatersafari.org. You can follow it on the day of the race pretty easily, the website changes on the day of the race to show the tracking and real time results. It's kinda fun to watch from the computer with the real time tracking. I appreciate and all support, even if it's virtual!


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## thumpergirl (Apr 27, 2014)

RepProdigious said:


> Scroll up a bit, thats exactly what i linked you earlier.



Rep, thank you. That one is 320 lumens, and I don't know enough to know if that would last as long as I need it to because it's over my lumens requirement. It's the closest one I've seen so far, for sure.  What will that do to the battery draw?


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## thumpergirl (Apr 27, 2014)

jabe1 said:


> The Solarforce drop-in is too bright, without the needed runtime (3 nights. the race is 71 hrs long). The Pelican can't be operated from 11' away.
> 
> Yes, she needs a switch on her battery pack, or inline on the power cord.



jabe1, you get an A+ in 'pays attention'. you are right on the mark, thank you! runtime is important. i could be out there for up to 3 nights. if I have to use a seperate battery pack each night, that's 3 packs. that takes up valuable space in the hull (and it is tiny - space is very limited) and it adds to the weight. This thing already weighs enough that it's hard for me to portage. Gotta operate from the seat I'm sitting in - can't stand up. The light is 11' in front of me, and I can't move my butt; only my arms.

The only switch I really need is the 2 pin connector. The light is on when it's plugged into the battery pack (the pack sits right next to me, within arms reach), and off when unplugged.


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## jabe1 (Apr 27, 2014)

Have you tried contacting Nailbender or Vinh yet? I really think they could help.

I mentioned a switch instead of just the plug, partly to make reverse polarity protection unnecessary.

Look for them in the custom and modified B/S/T forum.


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## DUQ (Apr 28, 2014)

thumpergirl said:


> jabe1, you get an A+ in 'pays attention'.



Sorry I just skimmed your post and all I got was *100 Lumens, runtime and waterproof* :fail:


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## thumpergirl (Apr 28, 2014)

jabe1 said:


> Have you tried contacting Nailbender or Vinh yet? I really think they could help.



Not yet, I contacted DIWdiver since he posted directly on this thread. If I don't get a reply in a day or two I'll contact the others that you mentioned. Thanks for the leads.


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## thumpergirl (Apr 28, 2014)

DIWdiver said:


> 200 lm or less P6 dropin with 18V input capability (see my link in your other thread)



How do I know if a drop-in has reverse polarity protection? This could easily be plugged into a battery pack that may not be correctly wired. 

What about this drop-in? http://www.dx.com/p/cree-q5-led-drop-in-module-3-7v-18v-input-11621#.U15Zd8epq_U

And one more question. Can I easily switch out a reflector in a drop-in? I can't find one that meets my specifications AND has a smooth reflector. They all seem to have orange peel, or at least the ones that have the voltage and lumen output that I require.


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## DIWdiver (Apr 28, 2014)

Polarity protection is easily added in your light body.

I actually suggested that dropin in your other thread.

Some reflectors are interchangeable, some arent. You won't know until you try, or someone else does. Though I suppose its sometimes apparent that they aren't, just from pictures.


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## thumpergirl (May 7, 2014)

DIWdiver said:


> Polarity protection is easily added in your light body.
> 
> I actually suggested that dropin in your other thread.



DIW - I was asking if the one you suggested in my other thread actually had polarity protection. I think the way I worded it was confusing. No matter now, parts are purchased!


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## Indexmill (May 7, 2014)

Just out of idle curiosity, what is a thumpergirl?


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## thumpergirl (May 8, 2014)

Indexmill said:


> Just out of idle curiosity, what is a thumpergirl?



Thumper = single cylinder motorcycle. I am an adventure rider and big advocate of 'less is more'. I own 2 thumpers right now, a BMWF650GS and Yammi WR250R, but single cylinder dual sport bikes.


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## thumpergirl (Mar 10, 2015)

Back at it again. For a quick follow up, I built several lights with the MR16 driver and they worked great. Best solution so far is Solarforce L2M host (has threaded shaft that can be removed to make it smaller), XM-L2 neutral white drop-in with OP reflector, some textured adhesive to go on the lens for better flood, MR16 1x3W driver, and PG7 cable gland. I had no trouble with mine last year and had a couple other people using them that really liked them. I intend to someday document the process and make it public and easy(ish) for someone to build their own light if they choose. Until then, they have this forum.

I did read that I could make the driver more efficient by removing the bridge rectifier diode since the input will always be DC. The more efficient I can make these, the better. Can anyone point me to the bridge rectifier diode on the MR16 driver? I *think* I know what it is, but I sure don't want to assume and get it wrong.

**Update, I think this is also what controls the polarity, so maybe I don't want to do this after all. It is highly likely that the light will get plugged into a battery pack the wrong way at some point.


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## thumpergirl (Mar 10, 2015)

I also have one other question. I've bought so many parts I can't keep track of what's what. How can I discern the MR16 1x1w, 1x3w, and 3x1w at a glance?


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## DIWdiver (Mar 10, 2015)

Congratulations on your success with the lights! How'd you do in the race?

A bridge rectifier is an arrangement of 4 diodes. Sometimes they are 4 separate parts, sometimes they are in one package. If it's one package, it will have 4 pins. Two will go the AC input wires, two will go to the rest of the circuit. If it's separate parts, there will be 4 identical parts. Each will have some sort of mark at one end. This is the cathode, and the other end is the anode. The bridge will have two parts with cathodes connected (this is the + output), the other two will have anodes connected (the - output). One free anode and one cathode will be tied to each AC input.

Some drivers intended to be used with batteries have bridge rectifiers at the input, some have "reverse polarity protection", which is usually a single diode, and some have nothing. A driver meant for AC will almost certainly have a bridge rectifier.

You can convert a bridge rectifier to a "reverse polarity protection" configuration and get half the efficiency improvement of removing the bridge completely. With this, it will work one way and protect the driver but not work if power is backward.

Another possible improvement is to change to a diode or diodes with lower voltage drop. Silicon diodes drop 0.6-0.7V, while schottky diodes only drop 0.1-0.5 depending on the part selected and the current through it. In a bridge rectifier, two at a time are working, giving a voltage drop of 1.2-1.4V for the silicon types, which are most common.

If you are up to the challenge, there's an even better way using an FET. It's a 'reverse polarity protection' circuit, but can drop as little as a few millivolts.

I can't help with the drivers. Maybe if we had pictures?


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## thumpergirl (Mar 13, 2015)

Hi there DIW! Race went well, 2nd in my category. Was hoping for a better time but, I had a much more 'eventful' race than anticipated. This is probably going to sound like fiction, but it's not. My rudder bent early in the race, my rudder cable broke, my bilge switch died, I had a run-in with a mystery creature in the river that bit my leg/butt and ended up with a large infection, either a gator or a 200lb catfish knocked me out of the boat near the bay, had a run-in with a coatimundi while stuck on spoil island in the bay whole stole some of my belongings (wish I was making this up because I really needed that emergency blanket), and a shark passed me near the finish and it scared the $*** out of me. BAM. Gearing up to do it again this June, hopefully far less eventful this year.

Am posting pics of the 1x3W MR16. Would love to know all the parts and components and how to make it more efficient. Have no idea how anyone would work on a such a small board, but I suppose it can be done? Polarity protection is fairly important, efficiency is very important, and size is also very important. The MR16 barely fits into the p60 host. I'm willing to switch up hosts, but without purchasing a ton of them and trying to disassemble them to see if they'll work, I'm at a loss for what to get.

Main goal is still to have a very small, compact, lightweight waterproof light, highly efficient so longer battery life, less heat so less housing necessary, and somewhere around 300-400 lumens.

I digress, back to the driver... I would love to understand and know how to do all the driver improvements you listed above. Cost and time are a consideration as well. I've heard of the schottky diodes before, but that's about as far as my knowledge goes. I'd also like to know more about the FET. Keep in mind, all of these would need to be small and I need to be able to fit them in a P60 host (unless I can go even smaller or somebody has a better idea that is cost effective). So, if a mod can't meet that spec then I'll probably need to come up with something else.

If you can look at the driver pics, help me identify the parts, and recommend improvements that fit the criteria, that would be awesome.

Can't thank you enough for your help. I really enjoy learning about this stuff and building these lights. Another addiction...  I'll post up a couple pictures of the lights I've built so far in another post. Hoping this thread helps someone else out who is trying to do this.


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## DIWdiver (Mar 13, 2015)

You know, the Chinese have a saying, "may you lead an interesting life". It's not a blessing, it's a curse.

Sounds like a good race to have in the history books. You certainly won't have a lack of stories to tell!

Anyway, just google "FET polarity protection", then click on the 'images for fet polarity protection' link, and you'll see gobs of descriptions of how to do it. The bridge rectifier in your pics is comprised of the 4 black blocks next to the pins on the upper image. Replacing them with one of these http://www.digikey.com/product-detail/en/NTD4906N-35G/NTD4906N-35GOS-ND/2194521 would boost the driver efficiency by 8-9%. If you ensure your battery voltage never exceeds 20V, you can use the simplest of the circuits you'll find (just battery, FET, and load).

This will provide reverse battery protection (not reverse battery operation like you have now) with virtually no voltage drop - something on the order of 0.002V.


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## thumpergirl (Mar 15, 2015)

So, I googled "FET polarity protection" and a bunch of foreign languages appeared (aka circuit diagrams?). I'll keep studying.

Reverse battery protection is great, I don't need reverse battery operation but I don't want to destroy a light if it's plugged into a battery pack that is incorrectly wired. So if it doesn't turn on, that's fine, just don't want to ruin anything.

So two things - 

1) I do want to know how to modify the MR16 driver with the FET. So the bridge rectifiers are the 4 black blocks. I can just remove them without any special tools? They are sooo tiny. I suppose I'll need a different tip for my solder iron, and some tweezers for this? Solder paste? So I replace the 4 blocks with 1 FET (from here: http://www.digikey.com/product-detail/en/NTD4906N-35G/NTD4906N-35GOS-ND/2194521). Can you tell me, exactly, do I solder this? I've removed 4 chips and am adding 1.

2) Also, I would like more information about the simple circuit you talked about (battery, FET, and load). We can always assume under 20V (My battery packs will never exceed 18V. They are always 10 lithium AA batteries, never exceeding 19V), always DC power, and need reverse battery protection. So the most efficient way to build that in a tiny package less than 17mm (inside diameter of host). Would that be starting with the MR16 board and modifying it? I love the idea of little voltage drop.


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## DIWdiver (Mar 15, 2015)

Each of those 4 parts individually is a a diode (aka rectifier). A bridge rectifier is the combination of 4 of them in a specific configuration to turn AC into DC. 

If the board you have barely fits, then the best way is probably to modify it. There aren't many drivers around that small, especially ones that can handle 19V.

Yes, you'll unsolder those 4 parts and replace with the new one. You probably don't need a new tip, and you definitely don't need paste. The tools I like are solder wick (which is a strip of braided copper that will soak up the solder) and a dental pick. At work I usually keep a 1/8" tip on my iron, and I solder much smaller stuff than that.

I first wick off most of the solder (place wick on the solder, then the iron on the wick. You'll see when the solder starts to vanish). Then use the dental pick to put just a tiny bit of force to pry off the part, and hit it with the iron again. Because the terminals at the end of those parts are flexible, you can lift one end at a time.

The only things to be careful of are using too much force or keeping the heat on too long. Either can cause the metal foil to separate from the fiberglass backing. If you can, it would be good to practice on a board you don't care much about!

So in the circuit you are going to build you will have a battery , an FET, and a load. The first two are pretty obvious, the load consists of the driver and the LED. To be more specific, it will be what's left of the driver after you remove the bridge rectifier. Before you remove the diodes, you want to see how they are connected. Two of them will be connected at the cathode (the end with the whitish band across it). This will be the positive (+) side of the load. The other two will be connected at the anode side (opposite the cathode). This will be the negative (-) side of the load. The two input pins will each connect to one anode and one cathode. One pin will become your +battery connection and one will become your -battery connection. Probably best to determine this by playing around to see how the FET will connect most neatly.

You want to connect together the +battery pin, the +load connection, and the FET Gate (G). Then you want to connect the FET Source (S) to the -load connection, and the FET Drain (D) to the -battery pin. That's it!

Keep in mind that the big metal tab on the transistor is connected to the center pin, so you'll need to make sure it doesn't contact anything it shouldn't. A wrap or two of electrical tape should suffice.


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## thumpergirl (Dec 6, 2015)

More questions!

These lights are working well, but I'm not a fan of the slow dimming effect. Is there a way I can add a voltage regulator to this circuit to improve the dimming issue? I would like the LED's to get a constant voltage until the batteries are too low to function, instead of dimming. The voltage regulator would need to fit into a host with an 18mm inside diameter. I also need to understand how to hook it up to the MR16 driver and battery.

There are two configurations:

#1) 1x5W MR16 driver feeding a single XP-L LED,
#2) and the second configuration is a triple XP-G2 wired in series, driven by an MR16 3x3W driver.

Mouser Electronics seems to have what I need, although I'm not sure exactly why to buy and how to put it together. Here is an example of what I think I need:
http://www.mouser.com/Search/ProductDetail.aspx?qs=QRsLLuHQazCCdYrl%2bmPkLQ==

Each one has a different output voltage and different output current. How do I know which one I need?
I'd like each of the lights above to run around 400 lumens, plus or minus.
The XP-G2 triple is an S4. At 350mA, it's lumens are around 186-195 (according to http://flashlightwiki.com/)
If each ran at about 350mA, the lumen output would approximately be 186-196 X 3 lumens, or between 558 and 588 lumens.

Is the following correct? :
If each LED in the triple were driven at 350mA, and they were wired in series, then I would need a 3x1W MR16 driver - each LED gets it's own 350mA.
If each LED in the triple were driven at 350mA, and they were wired in parallel, then I would need a 3X3W MR16 driver - all LED's share ~1000mA or 1amp.
The single XP-L V6 could be driven by a 1X5W MR16 driver to deliver around 500 lumens.

Assuming that is correct:

A) How do I know which voltage regulator to buy? Which is the correct output voltage and output current and why?
B) How is it wired in the circuit? Is it is wired between the driver and battery, or the driver and LEDs?

Of note:
- the battery pack that is driving this light is 10AA lithium batteries, outputting 18V when fresh. 
- this circuit needs to be as efficient as possible. Battery life is important and needs to be at least 9 hours run time. More is better.

*** OR *** does the MR16 driver already have a voltage regulator on it, and if so, why is the light dimming? I'm not able to look at the parts and know what they are yet. MR16 pics in post above this.

Thanks CPF! (and DIWDiver for all of your help to this point!)


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## DrafterDan (Dec 6, 2015)

I'm glad DIW can help you TG, because I was lost several months ago.


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## DIWdiver (Dec 7, 2015)

Maybe it's time for a crash course in regulator types and what they do.

Think about what the 'ideal' battery would be. It would have a fixed voltage, and would give you however much current you ask of it. Say you have an ideal 3V battery and a handful of 3V light bulbs, each of which draws 1A at 3V. Put one across the battery, and it draws 1A. Add another one in parallel (so it's directly across the battery too), and it will also draw 1A. The battery would now be supplying 2A, half of which goes to each bulb.

Now say you have a real battery, which is about 4V under load when fully charged, and about 3V when nearly discharged. This is pretty much what a lithium ion battery does. If you want to run the bulbs at a constant 3V, you need a voltage regulator. This will take the variable voltage from the battery and turn it into a fixed voltage. Like the ideal battery, its output is a fixed voltage at whatever current the load requires.

But say you had LEDs instead of light bulbs. Unlike light bulbs, LEDs don't do predictable things at specific voltages. If you buy a "3V" LED and put it on a 3V voltage regulator, it will likely NOT draw it's rated current, but something slightly or substantially higher or lower, and this would affect the light output, heat generation, and lifetime of the LED. You might find that to get it to draw the rated current, you need to supply one with 3.1V, and another with 2.9V. It gets even worse, because as an LED heats up, the required voltage drops!

So what's to be done? We want a _current_ regulator instead of a voltage regulator. The ideal current regulator would put out a fixed current at whatever voltage the load requires. Set it for 350 mA and put that same 3.1V LED across it, it will draw exactly 350 mA at 3.1V. As the LED heats up, the current would stay the same as the voltage drops. In fact if you put the two LEDs in series across the output, you would get the required 6V at 350 mA.

Now obviously real regulators have limits. A 350 mA current regulator will have an output voltage range, say 2.5-8.0V. This can easily handle one or two of almost any white LED. Say you put your XPL across it. It will draw 350 mA, and the voltage will probably be a bit below the XPL's rated voltage, because the current is rather low for an XPL. Put an XPG across it, and the current will be the same, the voltage will be a little higher. But now say you put that triple XPG in series across it. The LEDs would want around 10V, but that's beyond the regulator's range and you will not get the desired result. Say you put a 2.0V LED across it. Some red LEDs are this low. Again it's outside the regulator's range and you will not get the desired result. 

So in most cases, a good LED driver is actually a current regulator. Sometimes they are adjustable, and there are different ways of doing this, and there are other bells and whistles, but at their heart they should all be current regulators.

So why do your lights have this dimming problem? Because the current regulators aren't very good at their job. As the input voltage changes, the output current changes. This is common in very inexpensive switching regulators. The drivers you have are 'buck' type switching regulators. This is quite a common driver type for use in flashlights. It allows for converting a higher battery voltage to a lower LED voltage at high efficiency. Done well, it's capable of >90% efficiency, and rock-steady output to the bitter end of battery life. Done poorly, well you've seen that.

So there are two possible solutions to your problem. One is to have not an additional regulator, but just a better one. You'd probably get a bit (or maybe quite a bit) better efficiency and much better output regulation.

This may or may not be easy to do. I'm not much of an expert on what's available for purchase to fit a particular light.

The other possible solution is to add a voltage regulator in front of your current regulator (driver). If you supply your driver with a constant voltage, it will have a constant output. This is kind of a band-aid approach though, as it will add additional losses thus decreasing overall efficiency and it will also restrict the input voltage range by raising the minimum battery voltage required for proper regulation. The latter may not be a concern for you given the parts you are using.

Would it be possible to add a voltage regulator in the battery pack? There are lots of cheap buck type voltage regulators available, but I really doubt you'll find one to fit in an 18mm tube.

This post is getting pretty long, so maybe we should discuss choosing regulators later.


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