# Best way to mod a Surefire for more power?



## Brasso (Jan 3, 2010)

I know next to nothing about incandescent lights. What would be the best way to mod a 6P for more output?

Is there a good drop-in bulb that can get 200 lumen? Best battery configuration? Run time?


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## Niconical (Jan 3, 2010)

For a 6P to get more power the most obvious choice would be 2xRCR123A and a P90 lamp from a 9P. 

For more, 2x IMR16340 and a P91 lamp for some wow factor. 

You can also use a 17670 battery and a 3.7v lamp (from LumensFactory) but that doesn't increase output (maybe a little), but it does make it rechargeable. NOTE: LumensFactory lumens are measured differently to Surefire lumens, so those apparently high output numbers on the LF lamps are not a direct comparison to the Surefire P60. 

All 3 battery types available here.


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## leukos (Jan 3, 2010)

Niconical said:


> For more, 2x IMR16340 and a P91 lamp for some wow factor.


 
That setup will be 400+ lumens, twisty switch only.


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## nfetterly (Jan 3, 2010)

Niconical said:


> For more, 2x IMR16340 and a P91 lamp for some wow factor.



That is one of my favorites!

I also like the custom FM/Carley 1794 that Nite had a second run made of, that goes into the custom FM holder - but the P91 is alot easier route.

The AW 3 level soft start switch that goes into the surefire tail is a nice upgrade as well (this turns it into a "soft clicky" - it doesn't really click - but push / release moves it on & between levels - it will take the high amperage). Available from AW and on lighthound.com (it's about $50 for the switch guts).


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## Brasso (Jan 3, 2010)

So the factory surefire tailcap won't work with a P91 and the 16340's? Even the twisty/momentary switch? What's the runtime like with this setup? What's this FM holder?


If I decided to go this route, would 2 IMR18650's run the P91 OK?


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## Inliner (Jan 3, 2010)

Yes, factory 6P tailswitch will work. Clicky switches cannot. Runtime will be less than 10 min and it will get very hot.


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## Dioni (Jan 3, 2010)

*+1* on P91 with 2xIMR16340


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## FlashKat (Jan 3, 2010)

Simple mod would be Lumens Factory drop ins that you would decide on.


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## ampdude (Jan 3, 2010)

Surefire clicky switches have always worked fine with the Surefire P91 and always will. I don't know what clicky switches you guys are referring to, or what you are talking about at all. Perhaps some cheap aftermarket clickies, like the type sold on Ebay and Dealextreme. But I don't know of anyone who has ever had trouble with a Surefire P91 and a Z48/Z49 or Z58/Z59 switch, I certainly have not.


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## leukos (Jan 4, 2010)

Yeah, I guess the clickie warnings were mostly for E series clickies.


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## bstrickler (Jan 5, 2010)

You could get a 17670 or 18650 (if you bore the light), and get this:

http://www.lighthound.com/Lumens-Fa...ssembly-for-SureFire-C-P-Z-Series_p_1016.html

I haven't bought it yet, (no money for one right now) but it should be fairly good. Once I get some more money, I'm buying one. (Don't want to use my CR123's unless its an emergency). I like rechargeable options 

~Brian


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## kramer5150 (Jan 5, 2010)

you should be aware that run times will be very short with the 2xIMR16340 cells on a P91, like 10 minutes. Plus the voltage sag under load will prevent you form getting full output from that P91.

You should also be aware of the fire/safety hazards running a 2x Lithium cell setup at high current draw, and depleting them into cell reversal. You are basically WAY over 1C (discharge/capacity). That combined with excessive discharge into cell reversal can increase the likelihood of a fire/vent incident.

My suggestion would be to get the 6P bored for an 18650, add a solarforce 1x18650 extension and 2xIMR18650. That plants you in the ~400L+ range with longer run times.

You might also want to consider a P90 + 2xIMR18650 setup. If your goal is ~200L, the P91 is overkill at the expense of run time. Of course theres always the M60W, which will get you just over 200L With all the benefits of a warm tinted LED.... but that discussion is for the other forum.


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## ICUDoc (Jan 5, 2010)

kramer5150 said:


> you should be aware that run times will be very short with the 2xIMR16340 cells on a P91, like 10 minutes. Plus the voltage sag under load will prevent you form getting full output from that P91.
> 
> You should also be aware of the fire/safety hazards running a 2x Lithium cell setup at high current draw. You are basically WAY over 1C (discharge/capacity), which can be very dangerous.



I think the IMR cells are easily capable of this current draw.


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## n2deep (Jan 5, 2010)

kramer5150 said:


> you should be aware that run times will be very short with the 2xIMR16340 cells on a P91, like 10 minutes. Plus the voltage sag under load will prevent you form getting full output from that P91.
> 
> You should also be aware of the fire/safety hazards running a 2x Lithium cell setup at high current draw. You are basically WAY over 1C (discharge/capacity), which can be very dangerous.
> 
> ...





ICUDoc said:


> I think the IMR cells are easily capable of this current draw.




Well guys what is it? I was thinking about trying this. Can I safely run a 6P w/ the P91 on 2 IMR16340 cells? I have a love/hate relationship with this forum. I love all the wonderful info but every time I get on here it cost me. Oh well i'm a flashaholic!!


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## c0t0d0s0 (Jan 5, 2010)

ampdude said:


> Surefire clicky switches have always worked fine with the Surefire P91 and always will. I don't know what clicky switches you guys are referring to, or what you are talking about at all. Perhaps some cheap aftermarket clickies, like the type sold on Ebay and Dealextreme. But I don't know of anyone who has ever had trouble with a Surefire P91 and a Z48/Z49 or Z58/Z59 switch, I certainly have not.



Additionally, contrary to popular belief, my Z58 clicky has a lower internal resistance than a Z41 twisty. Yes it runs just fine with a P91 and IMR cells.


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## FlashKat (Jan 5, 2010)

Yes you can run this safely. Just short runtime.


n2deep said:


> Well guys what is it? I was thinking about trying this. Can I safely run a 6P w/ the P91 on 2 IMR16340 cells? I have a love/hate relationship with this forum. I love all the wonderful info but every time I get on here it cost me. Oh well i'm a flashaholic!!


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## kramer5150 (Jan 5, 2010)

ICUDoc said:


> I think the IMR cells are easily capable of this current draw.



Its not a matter of being capable, its more a matter of getting the most out of the P91. IMR16340 cells will sag under _that _much current draw (10 minutes to full discharge).

threads here...

https://www.candlepowerforums.com/threads/233057
380L OTF from 2xIMR16340
466L OTF from 2xAW17670

https://www.candlepowerforums.com/threads/229135
473 OTF from 2xIMR18650


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## n2deep (Jan 5, 2010)

Thank you Kramer for clarifying this. I need the most humanly possible LUMENS that I can get. :devil:


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## n2deep (Jan 5, 2010)

Thank you too FlashKat!


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## leukos (Jan 5, 2010)

kramer5150 said:


> https://www.candlepowerforums.com/threads/229135
> 473 OTF from 2xIMR18650


 
If you go that route, be aware of the risk, some CPFers are flashing their P91's with that setup.


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## ICUDoc (Jan 6, 2010)

kramer5150 said:


> Its not a matter of being capable, its more a matter of getting the most out of the P91. IMR16340 cells will sag under _that _much current draw (10 minutes to full discharge).
> You should also be aware of the fire/safety hazards running a 2x Lithium cell setup at high current draw. You are basically WAY over 1C (discharge/capacity), which can be very dangerous.



I just wanted to reassure all that your warning about safety with IMR cells was not applicable in this case (P91) as they are rated for much higher current draws.


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## kramer5150 (Jan 6, 2010)

ICUDoc said:


> I just wanted to reassure all that your warning about safety with IMR cells was not applicable in this case (P91) as they are rated for much higher current draws.



I should have been clearer in my post. Its not the high current drain by itself that creates fire/venting. Its the high current draw combined with the user excessively discharging the cells into polarity reversal. I edited my post above to elaborate on this a little.

So certainly YES the IMR cells can handle the current demands just fine.


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## Outdoors Fanatic (Jan 6, 2010)

n2deep said:


> Well guys what is it? I was thinking about trying this. Can I safely run a 6P w/ the P91 on 2 IMR16340 cells? I have a love/hate relationship with this forum. I love all the wonderful info but every time I get on here it cost me. Oh well i'm a flashaholic!!


Easily. The P91 only draws around 2.7A, the IMR 16340 cell is good for up to 4.4A.

Cheers.


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## Outdoors Fanatic (Jan 6, 2010)

kramer5150 said:


> I should have been clearer in my post. Its not the high current drain by itself that creates fire/venting. Its the high current draw combined with the user excessively discharging the cells into polarity reversal. I edited my post above to elaborate on this a little.
> 
> So certainly YES the IMR cells can handle the current demands just fine.


There is no fire/venting with IMR cells, it is a safe chemistry (LiMn). You must be confusing it with regular Li-Ion chemistry (liCo).


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## ampdude (Jan 7, 2010)

kramer5150 said:


> you should be aware that run times will be very short with the 2xIMR16340 cells on a P91, like 10 minutes. Plus the voltage sag under load will prevent you form getting full output from that P91.
> 
> My suggestion would be to get the 6P bored for an 18650, add a solarforce 1x18650 extension and 2xIMR18650. That plants you in the ~400L+ range with longer run times.
> 
> You might also want to consider a P90 + 2xIMR18650 setup. If your goal is ~200L, the P91 is overkill at the expense of run time. Of course theres always the M60W, which will get you just over 200L With all the benefits of a warm tinted LED.... but that discussion is for the other forum.



I'm sorry, but I think this is bad advice. The P91 is a pretty touchy lamp, and the bulb life is likely to be very short on a set of IMR18650's because of the cells lower internal resistance than RCR black label cells, and lower voltage sag than smaller cells. I know some people do it, but lamps and cells vary, so I think at best you're looking at a very short lamp life. And possibly bulb blackening after a short amount of use, reducing overall output. At worst you're looking at $31 going out in a quick flash. I think the best pairing for the P91 is the IMR18500 cells for lamp life, runtime and overall reliability.

If there were IMR17500's, I would probably recommend them instead, for reliability and bulb life sake. It's true you won't get the same brightness out of a pair of 16340's on a P91 that you will from a pair of 18500's or 18650's, but the cells are pretty easy on the lamp, despite the short runtime.


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## kramer5150 (Jan 7, 2010)

I humbly stand corrected regarding IMR chemistry. thanks Outdoors fanatic.

ampdude and leukos have pointed out a serious risk of instaflash and short bulb life in my IMR18650 suggestion. I do remember reading about this, but it slipped my mind.

OP I think you should take my posts with a grain of salt. I am merely regurgitating data and measurements taken by other members. And I admit, outside of playing around with other members lights, and using a P91/IMR setup on a night hike, I have not experienced first hand ownership. _You should weigh heavily the testaments from real first hand users instead of my own opinions._

No hard feelings I hope


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## angelofwar (Jan 8, 2010)

kramer5150 said:


> I humbly stand corrected regarding IMR chemistry. thanks Outdoors fanatic.
> 
> ampdude and leukos have pointed out a serious risk of instaflash and short bulb life in my IMR18650 suggestion. I do remember reading about this, but it slipped my mind.
> 
> ...


 
kramer, with regards to the "discharging" the cells too fast (i.e. high amp draw)...would this also be true with the 2X RCR123A's with a P90??? I have some RCR123A's laying around and several P90's, and would be interested in running this in my 6P...dangerous or no? I don't need this set-up, but would interested in trying it out, but it's not worth getting hurt over, or worse, losing a light . Any help would be greatly appreciated.


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## Outdoors Fanatic (Jan 8, 2010)

angelofwar said:


> kramer, with regards to the "discharging" the cells too fast (i.e. high amp draw)...would this also be true with the 2X RCR123A's with a P90??? I have some RCR123A's laying around and several P90's, and would be interested in running this in my 6P...dangerous or no? I don't need this set-up, but would interested in trying it out, but it's not worth getting hurt over, or worse, losing a light . Any help would be greatly appreciated.


Not dangerous at all. The P90 is a low-discharge energy-saving lamp assembly, no worries there. RCR123's + P90 = perfectly safe and fun.


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## angelofwar (Jan 8, 2010)

Outdoors Fanatic said:


> Not dangerous at all. The P90 is a low-discharge energy-saving lamp assembly, no worries there. RCR123's + P90 = perfectly safe and fun.


 
Thanks outdoors! Guess I know what I'll be doing tonight!


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## mdocod (Jan 10, 2010)

Regular RCR123 cells are going to have a true capacity somewhere around 500-650mAH, at loads above 1C (~0.5A), the capacity is likely to drop below 600mAH for most cells. The maximum safe discharge rate is around 1.2A for most RCR123 cells. The P90 will draw almost exactly 1.2A in most applications, (sometimes a bit less).

What I am saying is that; while 2xRCR123s can be used to drive a P90, it shouldn't be considered a "light load" on the cells just because the lamp is a lower output lamp compared to so many others out there... This configuration should be considered pushing the limits of the cell without going over them. Cycle life will suffer at these loads...

This is why, for pretty much ANY incandescent configuration possible with R123 size cells, I always recommend just going with the IMR16340s, as they will wind up delivering very similar true capacity at the loads of these incandescent lamps as one would get from a higher capacity rated RCR123, while at the same time, delivering a steadier output through the discharge and substantially better cycle life. 

This post should not stop anyone from giving the P90 a whirl on some RCR123s, it's a really fun little setup, when the cells wear out, just replace em with IMRs and be happy. 

------

In response to the original question here: I would suggest getting a pair of IMR16340s, (or maybe 4 or 6 of them so you have some spares), then picking up a few lamps to play with. I would personally suggest picking up a SR-9, EO-9, and P91 to start playing with. This will give you 3 noticeable increments of output each with it's own beam profile that will excel at various tasks. The SR-9 will have the most focused beam, and prove just as effective down range as the higher wattage lamps as a result. The EO-9 will have a slightly wider beam shape, with a step up in lumens to play with, while the P91 is basically just a wall of incandescent flood light that nothing can hide from. 


Eric


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