# Has anyone else experimented with 2x 16340 LiFePO4 cells with P60 lamp assembly?



## JCD (Mar 13, 2013)

I've found myself with several Surefire P60 lamp assemblies and some unused two cell Surefire hosts. I've been wanting to use the P60s, but I don't want to run primaries for normal use. I prefer guilt free lumens.

An Internet search yielded one thread on another Web site where a user successfully used 2x 16340 LiFePO4 cells with his P60 lamp assembly, with the caveat that the cells started at 3.35 volts each.

I started with two LiFePO4 cells that came off the charger yesterday. On the DMM, they showed a voltage of 3.45 volts. I put them in my PD30 (on turbo) for 15 seconds and rechecked the voltage. It read 3.35.

I grabbed a 6P that happened to still have a P60 installed. I installed the LiFePO4 cells and crossed my fingers. Success! It did NOT go  like I feared it might. (I once lost an MN03 trying LiFePO4 cells fresh off the charger.)

I haven't tested runtime, since my cells are 3-4 years old and well used. The user on the other site said he got about 20 minutes before experiencing significant dimming, but the cells he had pictured were the same generic DX cells I'm using. A quality LiFePO4 cell might last longer.

Now for some questions:

_Has anyone else tried this?__ If so: Were you successful?__ What was your starting voltage? What was your runtime (if you tested it)?_
_What are the theoretical issues with doing this? Should I expect significantly reduced bulb life?
_

Thanks for your feedback!


----------



## novice (Mar 13, 2013)

There are others that know far more about this than I, but I believe that you may be 'pressing your luck'. The P60 is designed to run off of 2 CR123a primary cells. When you turn this standard configuration on, 'voltage drop' takes place almost immediately, rendering the actual voltage to more like 5.5 'real' volts. As a new light guy several years ago, I tried running a P60 off of 5 AA NiMH cells, and fresh off the charger, the voltage was probably more like 5x1.3 volts instead of 1.2, which would have made for a total of 6.5 volts. I 'poofed' 2 P60 lamps before I decided that I was doing something wrong.


----------



## n2stuff (Mar 13, 2013)

I think the key here is old batteries. If you buy new batteries it will go Under load those old DX batteries have big voltage sag new IMR's batteries will insta flash that lamp like a flash cube.


----------



## JCD (Mar 14, 2013)

n2stuff said:


> I think the key here is old batteries. If you buy new batteries it will go Under load those old DX batteries have big voltage sag new IMR's batteries will insta flash that lamp like a flash cube.



Undoubtedly 2x 16340 IMR cells will destroy the bulb, but I didn't use IMR cells. I used LiFePO4 cells, which are a different chemistry, and have a lower voltage. During the vast majority of their discharge (all but the first several seconds), LiFePO4 cells (including brand new ones) will read 3.35 volts or below while resting. I'm not sure what their voltage is under load, but it is almost certainly much lower, closer to a fresh CR123A cell. Also, LiFePO4 can have a lifespan of about twice as many charging cycles as traditional lithium ion cells, so I doubt age is a factor here.

That does raise the question: _How do I test battery voltage under load?_ Is it as simple as touching one probe to the negative end of the battery and the other probe to the edge of the battery tube? Forgive my ignorance. I don't really use my DMM for anything besides monitoring the voltage on resting cells.


----------



## fivemega (Mar 14, 2013)

*If pair of LiFePO4 16340 don't flash the original P60 bulb, either your host has excessive resistance somewhere or cells are unhealthy.
Easiest way to check forwarded voltage to bulb is:
Run a pair of wires from positive (conical) and negative (cylindrical) springs of lamp assembly and connect them to DMM and read voltage while switched on.
If bulb doesn't flash then reading will be definitely under 6 volt.
I recommend using P90 with pair of IMR 16340
It's brighter and safer to use.*


----------



## cerbie (Mar 14, 2013)

I've tried two Tenergy LifePO4 cells (I no longer have working AWs). The brightness was greater, and the color temperature higher, so I stopped within the first few minutes.

Would a single protected 17670 have too little internal resistance, even at the lower voltage?


----------



## JCD (Mar 14, 2013)

fivemega said:


> If pair of LiFePO4 16340 don't flash the original P60 bulb, either your host has excessive resistance somewhere or cells are unhealthy.



I just tried each of all sixteen possible combinations of two 6P hosts, each with stock Z41 and McClicky, two P60s, and two different pairs of cells, with identical results. It is exceedingly unlikely that the results are due to excessive resistance in the host. It's only slightly less unlikely that the cells are faulty, given that neither pair flashed a bulb. I do plan to order new ones very soon, at which point I'll be able to rule that possible fault out with even higher confidence. At this time, the most plausible explanation is that LiFePO4 cells, after being discharged to 3.35 volts resting, are reasonably compatible with P60 lamp assemblies. The real question right now is how their use with the P60 affects bulb life.



fivemega said:


> Run a pair of wires from positive (conical) and negative (cylindrical) springs of lamp assembly and connect them to DMM and read voltage while switched on.



I'm not understanding from your description How I can run wires from the lamp assembly and switch the flashlight on with those wires connected.



fivemega said:


> I recommend using P90 with pair of IMR 16340



My preferred combo is P90 and 2x 17500 cells. However, the whole point of the current experiment is to find a use for my two cell hosts and P60 lamp assemblies without resorting to primaries.


----------



## n2stuff (Mar 14, 2013)

Sorry I didn't see your batteries were A123's.
Here is a simple way to check your batteries health.

http://laserpointerforums.com/f67/h...es-how-measure-internal-resistance-57576.html


----------



## JCD (Mar 14, 2013)

n2stuff said:


> Sorry I didn't see your batteries were A123's.
> Here is a simple way to check your batteries health.
> 
> http://laserpointerforums.com/f67/h...es-how-measure-internal-resistance-57576.html



Interesting. Thanks for the link. 

If I'm reading the instructions correctly, essentially the resistor and the DMM are connected to the battery in parallel? Is that correct?


----------



## ampdude (Mar 14, 2013)

JCD said:


> I just tried each of all sixteen possible combinations of two 6P hosts, each with stock Z41 and McClicky, two P60s, and two different pairs of cells, with identical results. It is exceedingly unlikely that the results are due to excessive resistance in the host. It's only slightly less unlikely that the cells are faulty, given that neither pair flashed a bulb. I do plan to order new ones very soon, at which point I'll be able to rule that possible fault out with even higher confidence. At this time, the most plausible explanation is that LiFePO4 cells, after being discharged to 3.35 volts resting, are reasonably compatible with P60 lamp assemblies. The real question right now is how their use with the P60 affects bulb life.



The older NiCad Surefire B65 battery I just measured fresh off the charger has an open voltage of 5.68V and that seems to be about average in my experience. However the last battery cell in the pack is kind of warm, so that means the battery pack probably won't last very much longer. Fresh CR123A's are around 3.3V each. However not only are the LiFeP04 cells a greater voltage to begin with, but (and this is the real problem) their voltage doesn't sag as much under load. So that is why they have a reputation for flashing 6 volt lamp assemblies.

The Surefire 6 volt lamps are in general more robust than a lot of the other 6 volt lamp assemblies out there like those sold by Maglite, Streamlight or Brinkmann, ect. The Maglite Krypton bulbs are pretty tough for overvoltage though. I think the P60 and MN03 are both meant to be about 4.8V bulbs with normal voltage sag of fresh lithium CR123A cells. The size of cells matters as well as larger cells of a given chemistry will have less voltage sag than smaller ones under the same load.


----------



## JCD (Mar 14, 2013)

ampdude said:


> However not only are the LiFeP04 cells a greater voltage to begin with …



Fresh off the charger, they measure ~3.6, but settle down to 3.35 very quickly (within 15-60 seconds in my Fenix PD30 on turbo). For this reason, I've been "un-topping" them off down to 3.35 volts before using them with the P60. I'm pretty sure they would flash the P60 otherwise.



ampdude said:


> The Surefire 6 volt lamps are in general more robust than a lot of the other 6 volt lamp assemblies out there like those sold by Maglite, Streamlight or Brinkmann, ect. The Maglite Krypton bulbs are pretty tough for overvoltage though. I think the P60 and MN03 are both meant to be about 4.8V bulbs with normal voltage sag of fresh lithium CR123A cells. The size of cells matters as well as larger cells of a given chemistry will have less voltage sag than smaller ones under the same load.



Interestingly, I tried the LiFePO4 cells in my Streamlight Night Com (2x CR123A cell Xenon version) without flashing that bulb, also.

How can I test the voltage sag for cells with a particular lamp assembly (or LED drop-in, for that matter)? Is there a relatively easy way to do it?


----------



## n2stuff (Mar 14, 2013)

JCD said:


> Interesting. Thanks for the link.
> 
> If I'm reading the instructions correctly, essentially the resistor and the DMM are connected to the battery in parallel? Is that correct?



You got it. Just that simple.


----------



## DragonHead (Apr 3, 2013)

Does anyone know how much the LED version P60's can take? (P60L-WH) I have been running the tenergy type LiFePo cells with no problems,"yet". Will my Li Ion cells fry it? can not find any voltage ratings for that drop in.


----------



## välineurheilija (Apr 3, 2013)

DragonHead said:


> Does anyone know how much the LED version P60's can take? (P60L-WH) I have been running the tenergy type LiFePo cells with no problems,"yet". Will my Li Ion cells fry it? can not find any voltage ratings for that drop in.



I hear the P60L can take at least 9 volts because its the same module for example 9P. I have used it with two AW IMR 18350 with no problems 


Sent from a mobile telephone


----------



## BIGLOU (Apr 3, 2013)

Edit: already answered: DH since the P60L (P60L-WH) is made to use with a 2 cell 6V (6P/G2) and a 3 cell 9V (9P/G3) you are good. So you can even use the RCR123s at 4.2 volts off the charger= 8.4 V and also be good to go.


----------

