Building P60 DropIn for SureFire G2

Jonas

Newly Enlightened
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Jul 3, 2012
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19
Location
Northern Germany
Hi CPF

I am reading in CPF for quite a while now.
But this is my first post as I need some help and maybe ideas from you.
I am more the realistic lumen guy.
For me a constant brightness is more important as a short time working turbo mode!
No need for SOS/strobe etc..
Iindirect accessable slow beacon is nice, but that depends...


What I would like to do

A SureFire G2 host is sitting around for a long time now - empty.
I need a dropin for it but could not find the "perfect" one for me.
If there is one that fits the following specs, I am happy for some recomendations!
I like it to be perfect and good quality (like Oveready dropins), do not mind to spent a bit of money for it to have it as I want it.
I would like to build it myself as I have all the needed knowledge.
The main thing I could not find is a good driver that fits all my needs.
I am also happy for recommendations on other parts as well...no question!


Here is what it should have:

--> P60 format, must fit a SureFire G2 without having a gap between head an body as it is the case with (for example) oveready dropin
--> spring or massive gold plated pad for positive contact, no thin layer on pcb itself!
--> XM-L2 / XP-L or other LED that delivers a good mix of flood and spot with the right reflector (no thrower combination!)
--> OP reflector with brass or copper pill (found one that fits my needs from fasttech for XM-L led) but did not buy it yet
--> led with neutral color temperature (lets say between 4000k and 4500k)
--> capable of handling 1x li-io (unprotected) or 2 CR123
--> voltage range 2.8V - 6V
--> very stable regulation on both configurations of cells down to 2.8V [important!]
--> reverse battery protection
--> battery warning at a slightly higher voltage as forward voltage of led (lets say 3V) [important!]
--> low voltage shut off (~2.5V, better little bit higher)
--> 1 or 2 modes (lo / hi or just hi)
--> no mode memory
--> no PWM, only if very(!) high frequency
--> hi mode should be max 300 lumen (XM-L2 neutral white U2 does that at 700mA and 85°C, even more at 25°C)
--> lo mode should be about 1/10 of hi, for this case 30 lumen

What I am up to is a dropin with a good runtime that does not create a lot of heat.
Should be able to run at hi constantly in the G2 host without overheating the led/driver.
To know when the battery is depleated is one of the most importatnt things, next to constant brightness over entire battery life. I hate a dimming light! For me at the end better shuts off at full brightness insted of doing long dimming.
Battery warning could be blinking (3 times or so) when regulation is not capable of driving any of the two modes at 100% anymore or
switching from hi to low at same case and do blinking only in lo mode when not capable of runnig at 100% in lo mode. For example the battery warning HDS systems using is what I like!

All that leaves a thight spot to focus on.
I am ok with leaving the track a litte bit to have something that fits the most important points.
One is that I would be okay to have it optimized for li-io for example or just hi mode insted of hi / lo.

Hopefully I mentioned everything I was thinking about.
I very much apprieciate any comments that help me building that dropin! :)
 

Woods Walker

The Wood is cut, The Bacon is cooked, Now it’s tim
Joined
Jun 8, 2008
Messages
5,433
Location
New England woods.
--> P60 format, must fit a SureFire G2 without having a gap between head an body as it is the case with (for example) oveready dropin

I believe it's the O ring that provides the water proofing not contact between the head or body.
 
Last edited:

m4a1usr

Enlightened
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May 4, 2013
Messages
884
Location
Washington State
You have a few conflicting requirements that make using a G2 a bit problematic. Heat dissipation being the main concern. Since you already realize that the Nitrolon body is a pretty good insulator your going to require a metal bezel/head to come close to your goal. Even if you were to stick with just a single rechargeable your desire for 300 lumens is the issue. While the spec sheet might claim 300 lumens at 700mah it's unlikely you will see that output. When I build mine I assume at least a 25% loss due to inefficiencies. However I tend to be on the conservative side in assumptions.

Having said all of that there are some decent choices of drivers that could be used. They vary on what limits you can accept. (low cut off/ levels/programing/etc). 700mah is a lot of heat encapsulated. And if using a 7135 powered driver the extra voltage from 2 primaries will add to the thermal load. What I can tell you is that the G2 dropins I have built for myself are based upon the Nanjg 101 and while it is a 3 or 5 mode driver it runs pretty good in a G2 providing you assume that it's not a light to use on high for very long (15 min or less). But your going to need to build it using a copper MCPCB with a solder bond on both sides, fill the pill with Fujik, use at least 24ga wire and wrap the reflector in copper/alum for a tight fit into the host body. And use a metal bezel/head

Now for just a single mode G2 P60 build my own favorite is the UltraFire branded buck/boost driver using the recommended parts and methods listed above. It will run between 470 and 550mah (apprx 300-350mah at the TC) at the led and likes a single rechargeable or 2 primaries. Output is about as bright (guesstimation) as a M61 and I have run one for over an hour continuously just to check the heat load. But it's a single mode. Still a good glove box light and is one that will take the abuse of being dropped and such.

I'm sure someone will chime in with their experienced build/ recommendations. And I love to fine tune my build techniques too!
 
Last edited:

Jonas

Newly Enlightened
Joined
Jul 3, 2012
Messages
19
Location
Northern Germany

I believe it's the O ring that provides the water proofing not contact between the head or body.

Yes, you are right! The o-ring is still covered by the head when using oveready dropin so water tighnes is preserved. But the gap is quite large and it simply does not look goot (at least I do not like it).


@ m4a1usr
Thank you for your reply!
Potting the dropin, adding more mass and using copper is what I prefere also.

You could be right with the heat issue at 300 lumens + heat from the driver.
Let's say Vf at LED is 3V at 700mA, that is ~2.1W at the led. With the drivers loss of heat (at 1x li-io config.) we
are talking about ~2.5W to 3W of power total.
Is that realy to much and causes overheating (more than 85°C/185°F) in a full nitrolon host?
Yey I could use an aluminium head, but that is not the plan as I want to keep it all nitrolon.
The 1x li-io cell I will be using for this is the Sanyo UR16650ZTA 2500mAh (9.2Wh).
So very roughly calculated the dropin will run for max 3h on hi at ~300 lumens with the dropin power of 3W total.
For my opinion that should be fine with the full nitrolon G2.
Lets say: I would risk it!
But to make this more realistic a setup with 500mA for the led would be fine to!
Like I said, im am more after a perfect setup rather than highest lumen possible.
So less than 300 lumens is not a problem.

Lets make the thing a little bit more simple.

A driver with the following configuration would be fine:

- one mode (100% only)
- 1x li-io only (~2.8V to 4.2V range)
- 500mA cc regulation
- battery reverse protection
- battery warning at full brightness with slow blinking every few seconds or even less at ~3.2 Volts (Battery warning should kick in before led brightness starts to drop! Battery warning voltage > Vf led)
- shut off at not less than 2.5V to protect the cell

Like I said before, very good regulation/constant output and the battery warning before dimming are my main preferences here!
I was still not able to find a driver that has battery warning AND cut off at low voltage. :shakehead
 

scs

Flashlight Enthusiast
Joined
Feb 9, 2015
Messages
1,803
If there is sufficient compression on the o-rings, then yes, the gap does not affect water tightness. If not, then fully tightening the head or tailcap makes a difference. I have a couple of 6Ps with tail o-rings that must have mysteriously shrunk (lights are new and so are the o-rings). Now, water gets in when the tailcap is not fully tightened.
 

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