Need help with building first P60 type drop in.

Flashlight Modding and DIY Parts
1

I am completly new to this and could use some help.

I want to put together a 700 OTF lumen P60 style drop in. I am planning to use a pair of protected 18650 batteries to power it. The problem is I do not understand how most of this works lol.

Say I have a LED that can be operated at up to 3000 mAh but I want to run it at 2000 mAh, how would I accomplish this?

How do you know what mAh to run any given LED at to get the output you want?

How do you know which LED to choose to reach your goals?

So really I need to start with the basics. I don’t expect all this information to just be handed to me, I just need to know where to go to do some research so I can have a proper understanding of how all this works. I love learning new things and would really like to be in the know.

2

Welcome! It sounds like a fun project.

If you are going to run 2 cells in series into one LED, you will need a buck driver. The choices when it comes to buck drivers that will fit in the P60s are limited, but there are some around.

For LED output you can search for the Cree datasheets for your specific LED (XP-G2, XM-L2, etc.) or type in "crash testing xm-l2" or similar and you will find fellow BLF member's testing results at different currents.

If you want 700 lumens at around 2A, the Cree XM-L2 LED is probably the best match for you.

I would take a browse over at flashlightwiki.com, they have lots of great information there in an easy to digest format.

EDIT: One thing that I've found to be really useful when working on P60s is to use thermal adhesive to glue the MCPCB to the pill. I don't do this on most lights, but on the P60 it really helps because without the glue the LEDs wire can get cut and short when tightening the reflector onto the pill, or the LED can overheat if the reflector comes loose from the pill inside the light.

3

I’ve made a post for beginers that you’ll find very useful.
Check out my sig link.

4

I’m sure someone much more knowledgeable than I am will chime in… But since I was in your situation a very short time ago, and now I’m programming attinys and building boards from oshpark projects graciously made public by some of the awesome members of this forum… I figure I ought to give back a little.

Check out the flashlight wiki here .

Assuming you have a host that takes P60 dropins (I’m kinda partial to Solarforce, myself), and have a bare P60 dropin in front of you, you really only need a few things. Apart from a soldering iron and solder, you’ll need some sort of thermally conductive paste (or epoxy) - and then you need two main components…

1. A driver (a small microprocessor-controlled PCB board to determine the user-interface (UI) of the light, and 2. an LED mounted on an MCPCB (circuit board). The driver will need to be 17mm in diameter and the LED’s MCPCB will need to be 16mm in diameter. The current depends on your choice of driver.

I also recommend you get solder flux and a spacer to help center the LED.

Considering that you’re in TX, if you want to make things easy on yourself to start off with, ignore all China-based websites and go to mtnelectronics.com . There’s lots of great stuff for sale on many other sites, but if you’re trying to learn, most of them will confuse that process as they’re utterly riddled with incorrect information. I say this as I’ve got like 4-5 orders somewhere between China and my house. They have great stuff. They also have a ton of garbage for sale that doesn’t make any sense, and it’ll take a bit for you to be able to know the difference. MTN is safe, as is illumn.com (another good US seller)… But mtnelectronics is singularly-focused on flashlights and flashlight components. Stick to that for now. The proprietor, RMM on this forum, is from all accounts a great guy and I’ve spent way too much money on his store with zero regrets.

You said you wanted an output of 2.0A - the easiest and most simple way to accomplish this is to get you one of these and have RMM remove two 7135’s for you (an option selectable on the store). That’ll get you to roughly 2.2-2.3A, but some will be lost in the host due to inefficiency in the driver and current restrictions in the host (springs especially), so you’ll be pretty close to your desired 2.0A.

You’ll need an LED mounted on an MCPCB, which MTN also sells. Since you said you’re looking for around 700 lumens, your only option is an XM-L2 U2 or XP-L V5 at that current to get close to the 700 lumen number. An LED with a smaller sized phosphate die will throw light farther (XP-G, XP-G2, XR-E, etc), but will not have the output you’re looking for.

The driver will come with LED leads which will correspond to the + (red wire) and - (black or white or blue wire depending on driver. Once you’ve got all the parts and pieces, it goes together fairly simply - driver in the driver cavity, drop of thermal paste under the LED mcpcb, wires through the holes in the pill. Solder the wire from + on the driver to + on the LED board (usually red), likewise with the - wire (usually not red).

Hardest part in assembly is soldering the ground ring on the driver (spring side facing battery, wires toward LED, in case that wasn’t obvious) to the brass pill. This is where you’ll be glad you’ve got the solder flux as I’ve found it to be darn near impossible without it. Put flux on the ground ring and on the pill, bridge the two with solder to lock the driver in place and provide an electrical path to go from the ground ring through the host to the tailcap to the negative side of the battery via the switch.

Screw the reflector on (trying to get the LED as close to centered as possible - spacers help with this), put the huge spring on the exposed threads on the pill’s battery side, and that’s about it.

Hope that helps. Feel free to ask whatever questions you may have. This forum has been an irreplaceable reference to me, for which I am very grateful to the other members - and there’s a ton of great info and great people on here. Good luck.

5

Forgot to mention…. Using two 18650’s will be an awful lot more complicated than using one. The driver I linked cannot be used with two - it’ll be destroyed if you run it with two. Stick to one 18650. It’ll be much, much simpler.

6

RMM: Thank you for the input. I was actually browsing your store earlier and will be ordering from you for the same reasons that grantman listed.

CRX: Thank you for telling me about your guide, I’m about to read it now.

grantman: Thank you for the detailed reply, it really helped me a lot.

I was planning on using two 18650’s for increased runtime along with the fact that I have a Solarforce D18 host sitting here in need of a drop in. I was planning on using a Sportac triple XP-G2 in the D18 before thinking about building my own. If it’s going to be a royal pita to find a driver that will work with 8.4v I will just pick up another Solarforce L2P (already have one in HA III with a Lighthound drop in on my AR).

7

CRX: Just started reading your guide and all I can say is WOW. That must have taken a considerable amount of time to put together. I’ll be reading it for a while, it’s going to take some time to let it all soak in.

8

I actually started out in the exact same boat… first nice budget light I bought was a solarforce l2n with an extension tube to fit two 18650s… so I set out looking for a good buck driver that could handle 8.4v. For reasons I don’t understand and can’t explain (I’m not an electrical engineer… I work in commercial real estate), apparently it’s difficult to make a good buck driver that’ll fit in 17mm. Not that it can’t be done — there are some out there. But, for a P60 format, most of the decent buck drivers I’ve found that are 17mm are too tall to fit well in a P60 pill. Again, it can be done, and there are several ready-made dropins that’ll fit the bill…. but I don’t know of any good 17mm buck drivers that are readily available by themselves and aren’t too tall for a P60 (due to either two boards sandwiched together or utilize a toroid on top to help the buck circuit deal with 8.4v going to a 3.?v LED).

I searched high and low and eventually gave up. With the quality of cells available, I don’t think I’m missing out much by not having the second cell. Of course, thanks to this site, I now have more lights and batteries than I know what to do with, so I don’t run into runtime problems much anyways —- just grab another battery or another light altogether when one dies haha.

Could always go balls out with an MT-G2 led and a zener-modified Qlite driver - which would run great with two 18650’s in your light. It won’t throw light far at all out of a P60 reflector, and probably wouldn’t get too very hot at 2A, but it’d still get fairly warm. Fair warning: MT-G2’s are addictive. And expensive. Going that route would require a lot of patient filing to get the (smallest size available) 20mm LED MCPCB to fit into a 16mm hole in the P60 pill. Some might say it isn’t worth it since the huge LED in the little reflector won’t throw light very far…. but I disagree. MT-G2’s are freaking sweet. But I also have other bigger lights that I’d use to get the light to reach out and touch something farther away.

9

grantman: I’m just going to run the Sportac triple in the D18 and work with a single 18650 host for my project.

What are some other hosts that are better suited to my original goal?

10

If you’re sticking with P60 hosts, I may not be the one to ask — I’ve never strayed from Solarforce P60 hosts, with the exception of one terrible Ultrafire 502b that I don’t care for at all.

As far as other hosts… the Convoy C8 is a pretty easy place to start, and throws light pretty well for its size. If you open the requirements up past P60’s, the options are darn near limitless. Things start to get a lot more complicated. You might try and bribe RMM to scrounge up some more XinTD C8 MTN editions (side note, since I know RMM is reading… I want another one. they’re awesome.), which are - in my opinion - the best C8 host available. There are several brands making C8 lights, but in my limited experience, Convoy seems to be the most reliable and readily available and the quality is great for the price. The Ultrafire C8 I have is garbage in comparison, but they seem to vary pretty widely depending on where you buy them - some have reported good quality Ultrafire C8’s so I dunno. Convoys use the same size driver and LED MCPCB as P60 hosts, which makes them an easy first step into the vast and overwhelming world of flashlight hosts.

Past the C8 form factor (which seems like a natural second step past P60’s to me….or at least it was in my case), there are a great many options. There aren’t a whole ton of lights out there available as hosts only, but there are a fair number. Check out a few of the group buys on here, and look around in the flashlight modding subforum. It’s pretty subjective depending on what you’re looking for in terms of output, size and throw distance. In very general terms, larger lights throw light further than small lights, almost regardless of output. 500 lumens in a big reflector light might throw light three times as far as 3,000 lumens in a P60-size reflector. It all depends on what you’re looking for.

11

grantman321 thank you very much for the guide, I was looking to build the exact same thing, a P60 dropin and I was browsing BLF in search for a little guidance. I was wondering if a L2N host would be able to handle 2.8A or I should go the safe route with a 2A driver?

12

Or you could get all crazy like and order one of those custom made p60 drop ins that people only whisper about in hushed voices for fear of getting sunburned from someone shinning one on them…

Search Vinz P60 on this forum….

13

I’ve seen Vinz’ jewelery like dropins, drooled and moved on. Not budget friendly at all.

14

I really need to keep cost at a modest level. I just spent a chunk of change registering and building a SBR (Short Barrel Rifle) AR15 so I can’t drop too much on this…… right now anyway lol.

15

My l2n is currently pulling about 4.2A on high, but I almost never use it on high for more than 30 sec at a time.

I did a runtime & heat test with it at 3A and it never got too hot to hold…. It did get pretty darn hot though.

16

For a host, I would avoid the 502b. I have several of the Ultrafire type hosts, and the 502b is my least favorite. 501b has too much empty space in the head, so I only use those for low-draw 1A max drop-ins. I like my 504b as the drop-in fits much more tightly and takes very little foil-wrap to fill in the extra space to improve heat sinking.

If you want a quality host, just pick a 1x 18650 SolarForce. I don't have one personally, but those are all very well reviewed here.

Then hit RMM's store and get a big order together.

Orange peel drop in - http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=86&product_id=146

Smooth drop in - http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=86&product_id=147

Driver - http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=67&product_id=52 - buy several of these. They are 3-Amp drivers, but you can remove the 7135s to reduce current @ 350mA/each to get your desired level.

Insulation gasket for XM-L/L2 - http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=25_82&product_id=217 - to keep the emitter leads from shorting against the reflector.

Any XM-L2 emitter you like: http://www.mtnelectronics.com/opencart/index.php?route=product/category&path=60_61 - I prefer cooler tints, some like the Neutral better. Just get an assortment and build several drop-ins to find out what you like...

17

Well I’ve been doing some research and I think I’ve come up with a nice 750-800 emitter lumen build with roughly an 80 minute runtime on a single 3100 mAh 18650. That is if my math and understanding of how to calculate these things is somewhat correct.

Cree XP-G2 S2 2B

Qlite driver with two chips removed

Reflector, pill, and springs

Am I on the right track? Are my calculations correct?

18

keltex: I have a couple of the Solarforce hosts, a single and a double 18650. The single is currently running a Lighthound Cree R5 drop in and is mounted on my SBR. I’ve yet to use the 2x18650, but that will be changing soon once I get a Sportac triple.

I saw you post right after I posted mine, it seems I am on the right track. I’m just not sure if I figured runtime and lumens correctly.

Thanks for all the help everyone, I really appreciate it!

19

To be honest I didn’t fully understand some of what you said in the quote above first time around. Now that I’ve done quite a bit of research I understand completely and it sounds like it’s exactly what I want. I wanted the Sportac triples because of the flood, only thing I didn’t like was the single mode. Doing the build you suggested will give me the flood I want along with having multiple modes. I’ll also be able to have the extended runtime I wanted as well.

20

I had something of a feeling that might be the case. I built a Convoy C8 that’s currently running an MT-G2 a few months ago. It’s an easy but also lengthy process… lots of waiting on parts from China. The trickiest part is making sure the parts - which come from several different China-based sellers, most of whom have erroneous product descriptions - will fit the host you choose. I put mine together using a Convoy C8 - which has distinctly different threads than all of the other C8s for the pill and for the battery tube extension - both of which are more or less critical to build it into an MT-G2 light (which takes 6V instead of 3V and generates a fair amount more heat than the 3V Cree LEDs). To that end, I’m going to post links to the same parts I bought from the same sellers… which should reduce (but unfortunately not totally eliminate) the possibility that you get something in the mail 45 days after ordering it only to find the threads aren’t quite right.

Host: Convoy C8 Convoy C8 Flashlight Host - Black

Driver (Ready-made): QLite Zener Mod http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=67&product_id=53

LED: http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=60_77&product_id=71

Pill: Brass Pill for CONVOY C8 http://www.dealsmachine.com/best_180109.html

Extension Tube: Extension tube for CONVOY C8 http://www.fasttech.com/products/1630/10007058/1575200-aluminum-alloy-extension-tube-for-1-18650-c8-led

Some things to note. The pill is slightly cheaper here. It should fit a Convoy C8 — it’s advertised with the same exact picture as the seller from whom I bought mine, and a review on the site says it fits the Convoy C8 and NOT the Ultrafire C8. If you use an Ultrafire host, this pill should work. I don’t know where to get an extension tube for an Ultrafire/Tangsfire/Uranusfire/AnyOtherGenericFire C8, mainly because the Ultrafire C8 I have is of terrible quality and I haven’t bothered to do anything with it. They vary wiiiiidely from seller to seller. Apparently I choose poorly on that one. You could go the Ultrafire C8 route with the pill above from FT and use 2x 18350 batteries and thereby not need an extension tube. The runtime, however, will not be spectacular.

If you go the Convoy route as I did, you’ll need to file down the LED star to fit, and you’ll also have to drill out the holes in the pill for the LED leads. It’s annoying, but not difficult. You’ll likely also need to enlarge the hole in the reflector to fit over the MT-G2’s giant dome. Be careful tightening everything down — the reflector can rip the dome off the emitter and destroy it if it’s too tight around the base of the dome. Better to make the hole slightly too big to be safe.

In my opinion, the end result is worth the trouble. I use mine all the time. You could try to stuff the MT-G2 in a P60 light… but in my limited experience, they really can’t handle the heat well enough. The Convoy C8 with the aluminum pill swapped out for a brass one seems to handle the heat from the MT-G2 at 3A just fine. The other reason for the pill swap is the shelf on the brass one linked above is closer to 17-18mm instead of 16mm, so you don’t have to file the LED star quite so much to get it to fit. The reflector in P60 lights is also pretty small, so using an MT-G2 might not result in the most usable light for outdoor use. I did stuff one in a AA mini-maglight, and while fairly entertaining, it wasn’t very useful at all.

I’d give the MT-G2 C8 a try after putting together a regular C8. Getting the thermal paste just right becomes a lot more important when using a setup that generates more heat. None of this is difficult stuff… just a little tricky if you’ve never done it before. You can also DIY the zener mod with any 8*7135 driver using one of these kits from MTN. It’s a little cheaper that way. The zener mod is pretty straightforward - hardest part is not dropping and losing the tiiiiiny components. Wouldn’t recommend doing it over carpet.

I’ve read around enough to note that using well-matched, similarly-charged batteries is very important when in series. I dunno if it’s the same case with rechargeable batteries, but apparently 1 dead CR123a + 1 new CR123a = explosion. So be careful with that.