Malkoff M61 - Much brighter with RCR123s ?

Hi guys - first of all please pardon my horrible search skills if this has already been discussed. I did try to find something on this & am quite surprised I didn't.

Here's my question please: I own a Surefire 6Z that I've had for a very long time. I upgraded it with a Malkoff M61 drop-in thats rated to produce 320lumens out the front end. I really like this drop-in, it is (of course) much brighter than before when the light was stock. - - - I have tried Energizer and Surefire brand lithium primaries in this light and compared it to RCR123 protected rechargeables - Eagletac brand. Despite the voltage difference, there really doesn't seem to be all that much visible difference between the brightness of this light with primary versus rechargeable batteries. And when I possibly detect that the light might'maybe' be slightly brighter with the RCR123s, I wonder if its just my imagination playing tricks on me.
This is quite different than my experience with a Maratac 1xAA flashlight that I've had for about 4 years. With 14500 batteries that light is much brighter than with lithium primaries.
The Malkoff will handle the voltage, but have you found there to be much advantage in terms of brightness when using RCR123s ? I was considering also getting some AW RCR123s.
Thank you in advance for your comments -

The Malkoff M61 has a voltage of 3.4 to 9v's. That means that is stays in regulation from 3.4 to 9v. With 2 CR123's at 6v, you will stay in regulation from 3.4 to 6v's. Running 2xRCR123's, you will be in regulation from 3.4 to 8.4v's. You may be getting a few more lumens using the RCR123's, but your eyes may not be able to pick up the negligible lumen difference. The drop in is working fine. The advantage that you have when using RCR123's is that you can use them over and over again!

With your other Maratac 1xAA setup, your dealing with a low voltage setup. They are usually something along the lines of .8 to 4.2v's, depending on the set up that Maratac uses (I am not familiar with what internals they use). Using 1xAA you will have 1.5v's. Using 1x14500, you will have 4.2v's. The light responds to the higher voltage. The electronics of the internals may have a few different operating voltage ranges where it reacts to the higher voltage, but steps down at certain voltage levels. You may have longer run times with a single AA, but you will get more brightness for a shorter time with the higher voltage 14500.

I am no expert, but just trying to help. I hope this helps a little.

The Malkoff uses a boost circuit to make sure that it delivers a minimum amount of current to the LED. It requires a minimum voltage to achieve this but once that minimum is reached, it doesn't help to continue increasing the voltage. If more voltage is applied, the current draw from the cells just decreases and no additional current is delivered to the LED.

In the maratac, the driver is capable of delivering additional current to the LED if it has sufficient voltage (which it doesn't on a primary). But once you put a lithium ion in there, the ramp up the current delivery and actually does increase the output.

Technically, you would increase your "regulated" runtime by maintaining a higher voltage in the Malkoff such as with the lithium ions but the increased capacity of the primaries just about makes up for the lower voltage and by the time it drops out of regulation due to voltage drop, you've already outrun what the lithium ions can provide.

In short, they two circuits for the two lights are designed to do different things. Rest assured that the Malkoff is doing exactly what it's supposed to. The M61 is widely revered for its ability to accept a wide voltage range and still put out just exactly as much light as it was designed to.

I hope that helps. Please ask follow up questions if not. Also, I typed this on my phone so please forgive the typos.

Cheers!

-G

Yup! What he said! :goodjobtwothumbs

Thanks guys for kindly explaining this for me :thumbsup: I appreciate it.
I knew that with the Malkoff I was looking at bumping up voltage from 6v to 7.4v or roughly a 25% boost from the rechargeables over the primaries.
I also knew that the Martac was bumping up voltage from about 1.5v to 3.7v or almost a 150% boost in voltage, but wanted to know if there's more to it than that.
You've cleared this up for me, especially in regard to how the Malkoff works.

G's. By the time I fat fingered my way through that response, Chevy had time to respond and eat a sandwich. I guess I'm getting slow in my old age.

I'd swear I notice the same thing with my M61N LLL and M61N LLLL get considerably brighter when run on 2x RCR123 cells vs 1x 18650.

Travis.

If you'd like to simplify the setup even further, the M61 runs nicely on a single Li-Ion cell such as an AW 17670 or a Keepower 16650.