105 lumens Surefire 6P

[SJACKAL]

With R123s being the in thing I got myself a set too and also a P90 LA as an upgrade for my trusty 6P. Since the R123 Li-ions are rated 4.2v on fresh charge and dropped to 3.7v thereafter, and the P90 is rated at 7.25v and 1.15amps, two R123 should run the P90 with no problems. After seeing someone had done it and tempted by the cost savings of long term usage since I need to use my 6P frequently, I went ahead with it.

So I put them into my 6P and I am very happy with the results. I get about 25 minutes of burn time on one set of R123 before the output starts to decrease noticably and the beam starts to turn orange. It cost me a total of about US$50 to get the P90 and the R123 locally (4 batts & 1 charger) and I say the $50 upgrade is definitely worthwhile. Certainty better than upgrading the 6P to a 9P by buying a cell extender and running it on expensive Lithium CR123.

This gives me a 3 cell output in a 2 cell 6P body, 25 minutes of rechargeable guilt free 105 blinding lumens.

The only complaint is the beam quality of the P90 lamp, which seems to be a common problem but its another matter by itself.

/ubbthreads/images/graemlins/grin.gif

 

[dano]

Cool...Thanks for the tip!

-dan

 

[quartz]

how about using a P91 Lamp Assembly?

 

[suppin]

Welcome to CPF, quartz! The P91 runs fine with 2xR123s too. But so far, they've only been successfully tested with bare/unprotected R123s. P91s do not work with protected R123s as the current draw is over the discharge protection limit of the protected cells.

Do take some time to read up on the risks and dangers involved in using unprotected R123s first though. The proper care and precaution must be taken while using unprotected cells as misuse may lead to nasty consequences.

 

[AW]

How do I know whether the R123s are protected or not?

 

[udaman]

[ QUOTE ]
SJACKAL said:
With R123s being the in thing I got myself a set too and also a P90 LA as an upgrade for my trusty 6P. Since the R123 Li-ions are rated 4.2v on fresh charge and dropped to 3.7v thereafter, and the P90 is rated at 7.25v and 1.15amps, two R123 should run the P90 with no problems. After seeing someone had done it and tempted by the cost savings of long term usage since I need to use my 6P frequently...

/ / /


So I put them into my 6P and I am very happy with the results. I get about 25 minutes of burn time on one set of R123 before the output starts to decrease noticably and the beam starts to turn orange.

This gives me a 3 cell output in a 2 cell 6P body, 25 minutes of rechargeable guilt free 105 blinding lumens.

The only complaint is the beam quality of the P90 lamp, which seems to be a common problem but its another matter by itself.

/ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

Li-Ion come off the charger at about 4.2v typically, they are not 'rated' as such. They are nonimally rated for capacity at 3.7v, but this is with very light loads seen with devices other than flashlights /ubbthreads/images/graemlins/smile.gif. Underload the voltage will always be less for much of the runtime, or all of the runtime if sufficienty high enough load is placed on the cells. See this graph for much larger sized 18650 2400ma cells, and notice how the voltage is under 3.5v for more than 1/2 the runtime for all of the high current discharge plots: http://www.candlepowerforums.com/ubbthreads/showthreaded.php?Cat=&Number=721157

P90 is not really 'rated' at 7.25v, is it? Both p90 & p91 LA are designed for 3 x 123 primary cells, which under various loads suffer substaintial voltage sag, see SilverFox's test graphs on this thread. 123 Battery Shoot Out

P91 LA would most likely place too much of a current demand on such low capacity cells. Such R123's, are at most 650ma now, but in the future may be able to supply greater currents under higher demand applications. The LA would most likely cause the voltage to sag below 3.0v, putting the cells in danger of permanent damage from running below rated low voltage cutoff point.

In the P90, I'll take a guess that for much of the runtime the voltage sag of each R123 cell will put them below 3.5v, as such the bulb is either being underdriven, and is not as white as it could be, or the bulb in the P90 is actually a 6v designed bulb. Surely the P91 is around 6v design, because with Brock's tested results of 6.25v at 2.35a current drain, this means the 9v primary 123 cells are suffering from serious voltage sag, but the bulb must be designed for operation around 6v . If the P91 were of 7.2v or greater design, the output in a 3 x123 scenario would be painfully yellow from being underdriven!
http://www.uwgb.edu/nevermab/flash.htm