What should I feed my M61W?

OK, here's the thing. I've streamlined my lights and everything I currently own is 123 based and primarily RCR123 fed. My Malkoff M61W is my only 2x123 unit. It is hosted by the MD2 which is 18650 bored. So should I keep it easy and use RCR123 primarily or should I invest in a couple 18650 cells? I would assume a fully charged 18650 will have more capacity than dual RCR123's? I'm honestly most concerned about runtime as far as this light is concerned. So what should I do here and why? Thank you for the input!

Jason

I guess it depends if you want full regulation the whole time, or if you don't mind a long period of diminished brightness at the tail end of the run. Notice that this module is best run on 2 cells, but can be run on 1 if you want, but regulation changes.

Quoted From Oveready's sales page:

Malkoff M61 Drop In for P60 Applications
Balanced between throw and spill the Malkoff M61 is an outstanding room lighter and short to medium spotter. The Neutral Tint Beam is close to white in color.

• Cree XP-G LED
• Approximately 260 lumens (cool version)
  
• Orange peel reflector designed by Don McLeish (maker of the McClicky switch)
  
• Fully regulated output between 3.4 and 9.0 volts
• Below 3.4v it drops out of regulation and continues running until about 3v
• Full output runtime is approximately 2 hours on two CR123 primary batteries
• 93% efficient driver with 2 lithium ion cells
• Long taper as voltage drops
• Current draw of 650ma at 6 volts
• Solid brass heatsink construction
• Fits SureFire 6P, 6Z, C2, M2 and G2 flashlights.

POWER SUPPLY OPTIONS:

This drop-in runs on 1, but is optimized for 2 rechargeable cells
It will give full output on 2 cells until your cells are completely discharged
On 1 cell, it will run most of the way in regulated, then 'drop out' into a long continuous dimming

Click to expand...

Nick, I believe that a 18650, which is a larger cell (about the size of 2 123's) has more capacity than 2xRCR123? I guess what I am looking for is clarification, will the 2900 mAh AW P18650 rated at 3.6V give me longer runtime than 2 AW RCR123's?

Yes, I see your question now, and I am aware of of what an 18650 is.

I am not a battery expert at all, but I believe cells in series increase voltage but not capacity. (Someone correct me?) So two RCR123s will have twice the voltage of one (7.2v) but the same capacity as one (750mAh?). Thus, you will get high output for a shorter time with the RCR123s, or high output for awhile, and then lower output for a longer while with the 18650 since capacity on that one is 2900 mAh. If I am making sense....

If I am wrong, I hope someone tells me.

I've got an M61W that I run in an MD2.
With 2 AWRCR123's I get 60 minutes runtime, then the protection circuit shuts the light off.
With a single AW 18650 (2600mah) I get a full 120+ minutes before the light noticeably starts dimming.
I never run RCR's in this setup, I like runtime so it's 18650's for me.

scot said:

I've got an M61W that I run in an MD2.
With 2 AWRCR123's I get 60 minutes runtime, then the protection circuit shuts the light off.
With a single AW 18650 (2600mah) I get a full 120+ minutes before the light noticeably starts dimming.
I never run RCR's in this setup, I like runtime so it's 18650's for me.

Click to expand...

This is good to know! I just ordered a 2900mAh AW 18650 so maybe that 120+ will be bumped up a bit? Thanks!