Malkoff MC-E - which battery combo lasts longer?

I have a Malkoff M60W MC-E (5-13v input) that I want to put into a Surefire 9P.

Can anyone tell me which battery combination would run the light longer?

Option #1 - 3xRCR123 = 11.1 volts @ 750 mAh

Option #2 - 2x17500 = 7.4 volts @ 1100 mAh.

In other words, I'd like to confirm or deny if higher initial voltage can outweigh higher cell capacity in this situation.

Thank you

Just speculating, since I haven't tried either set-up...

I assume the capacities you list are for AW cells? The RCR123s have consistently tested closer to 550mAh, and IIRC the 17500s have generally tested slightly higher than their listed capacity. I doubt the difference in driver efficiency between 7.4V and 11.1V will be significant enough to make up for the difference in Wh of the batteries (~8140 for the 17500s vs ~6105Wh for the RCR123s).

Personally, I'd stick to two cells and get an 18mm body. A pair of 18500s will be close to double the Wh of three RCR123s in the same size tube.

I was kinda leaning that way myself. Thanks for the vote of confidence.

gswitter said:

Just speculating, since I haven't tried either set-up...

I assume the capacities you list are for AW cells? The RCR123s have consistently tested closer to 550mAh, and IIRC the 17500s have generally tested slightly higher than their listed capacity. I doubt the difference in driver efficiency between 7.4V and 11.1V will be significant enough to make up for the difference in Wh of the batteries (~8140 for the 17500s vs ~6105Wh for the RCR123s).

Personally, I'd stick to two cells and get an 18mm body. A pair of 18500s will be close to double the Wh of three RCR123s in the same size tube.

Click to expand...

Gene said his MC-E modules draw 1300mAh from 6v sources and 800mAh from 9v combos. So yeah, it does make a difference.

I assume you mean 1300mA and 800mA, not mAh.

It would matter only if the higher voltage reduced the current draw by more than the reduction in battery capacity.

Without any specific current draw data for 7.4V vs 11.1V, a run time estimate is a crap shoot. But for illustrative purposes, if 2x17500 has a capacity of 1100mAh and a current draw of 1300mA while 3x16340 has a capacity of 550mAh and a current draw of 800mA, then the calculated run times are:

2x17500: 1100mAh/1300mA = 0.85h
3x16340: 550mA/800mAh = 0.69h

Of course, you would replace the notional current draws with the actual values.

But if the M60 buck driver behaves like most constant current buck drivers, you'd have to double the input voltage to halve the current draw. Since that isn't the case here, the 2x17500 most likely will have a longer run time than 3x16340.

Here is MrGman's testing
https://www.candlepowerforums.com/threads/229135

Since the Malkoff MC-E is 100% regulated as you increase the voltage the mA current draw readings at the tail and LED drop. The 17500 option seems like a better choice to me of course.

Gene said the MC-E in his P60 drop-ins are driven at 2.4A at the LED.



MCE-Cool-----This is with a fan running but the unit is warmed up so the turn on peak readings up to 500 lumens will not be seen. Shows the regulation control in the driver chip.
Volts----------Amps-----watts-----lumens
4.53______0.35_____1.59____130.1
4.74______1.21_____5.72____349.0
5.06______1.76_____8.93____445.7
5.26______1.70_____8.92____430.5
5.51______1.76_____9.69____453.3
5.77______1.71_____9.84____445.7
5.98______1.66_____9.95____451.4
6.28______1.58_____9.93____447.6
6.54______1.48_____9.70____443.8
6.74______1.44_____9.72____443.8
7.02______1.38_____9.68____443.8
7.22______1.26_____9.12____449.5
7.51______1.21_____9.08____449.5
7.76______1.16_____9.04____449.5
8.01______1.12_____9.00____445.7
8.25______1.09_____8.99____445.7
8.48______1.06_____8.96____443.8
8.66______1.04_____8.99____449.5
8.82______1.02_____9.03____443.8
9.05______1.00_____9.01____443.8
9.27______0.97_____9.00____443.8
9.52______0.94_____8.95____443.8
9.94______0.91_____9.02____443.8

That's an interesting Power In vs Voltage In result. If the MC-E is wired in 2S2P, the driver seems to behave more like a boost-buck.

Justin Case said:

That's an interesting Power In vs Voltage In result. If the MC-E is wired in 2S2P, the driver seems to behave more like a boost-buck.

Click to expand...

Except that the MC-E is wired 4p and set for 2.4 amps from the driver.

The 2X17500 batteries will give you excellent run time performance and good rechargeable batteries. Go with the AW17500's and you will be happy in the longrun gunfighter.

For even more runtime I would send your 9P to get bored to accept the 18500 AW cells.
https://www.candlepowerforums.com/threads/234868

Electroguru also sells bored 9P bodies, which I really want myself. Then you could run 2 18500 cells and get even more runtime.lovecpf

17500 = 1100mAh capacity
18500 = 1500mAh capacity

The extra 400mAh may or may not be worth it to you since the 18500 bore will cost you with shipping around $20 dollars extra. For that price you could always purchase a couple more 17500 cells.

I run mine in a MD4 with 2 x 18650 2200mah's.

Whats the runtime on that setup?

MrGman said:

Except that the MC-E is wired 4p and set for 2.4 amps from the driver.

The 2X17500 batteries will give you excellent run time performance and good rechargeable batteries. Go with the AW17500's and you will be happy in the longrun gunfighter.

Click to expand...

I was actually trying to give the benefit of the doubt by assuming 2S2P to explain the relatively poor Pin vs Vin data. The 4P regulated behavior is still not as even as it could or should be IMO. The voltage headroom is also a bit higher than preferred IMO.

Justin Case said:

The regulated behavior is still not as even as it could or should be IMO. The voltage headroom is also a bit higher than preferred IMO.

Click to expand...

What do you mean by that? I'm running my M60W MC-E on 2x 18500 IMRs, and the regulation is EXCELLENT.

bigchelis said:

For even more runtime I would send your 9P to get bored to accept the 18500 AW cells.
https://www.candlepowerforums.com/threads/234868

Electroguru also sells bored 9P bodies, which I really want myself. Then you could run 2 18500 cells and get even more runtime.lovecpf

17500 = 1100mAh capacity
18500 = 1500mAh capacity

The extra 400mAh may or may not be worth it to you since the 18500 bore will cost you with shipping around $20 dollars extra. For that price you could always purchase a couple more 17500 cells.

Click to expand...

Or just get this -->> http://www.lighthound.com/LeefBody-...ry-or-3x123-Battery-HA-III-Natural_p_920.html

Not cheap, but you'll have the best money can buy.

Thanks gentlemen. I now have lots of options to consider.

I appreciate the wealth of information here.

Outdoors Fanatic said:

What do you mean by that? I'm running my M60W MC-E on 2x 18500 IMRs, and the regulation is EXCELLENT.

Click to expand...

This is what I mean. Power In vs Voltage In for the MC-E M60 has what I would consider to be large variations. The curve is far from the expected quasi step function. Also voltage in for full output (~5V) seems rather high relative to the 4P MC-E's paper spec of Vf~3.35V at 2.4A. As a comparison as to what can be achieved with a good driver design, TaskLED's hipFlex and hipCC have a voltage overhead of only about 0.5V.

Here is a graph for the driver behavior for a cheap DX6090 using a PT4105-based buck IC:


Or this one using an SOB1000 buck driver:


Compare the two above curves to the analogous curve for the MC-E M60:

Thanks, but I can't read these graphs... LOL

The M60 MC-E appears to have basically one step variation transitioning through 7V region. Not the end of the world. How about doing some comparison to some other 10 watt drivers for a more accurate apples to apples type comparison. Your first comparison is only 4 watts and the second is just a little over 6 watts. This is still a great light to run off of 2X17500 or 18500 or larger batteries from my personal usage. And it works with the Unique Continuously Variable tailcap whereas some other modules won't at all, so that says a lot about it.

Never said the Malkoff's Pin vs Vin profile was "the end of the world". However, an unnecessary extra 1W of draw costs you in excess heat and shorter run time (roughly 10%). I'll take a 10% improvement any day, especially when there are drivers available that can hit that mark.

Regardless of how you want to spin your description of the Malkoff driver's Pin vs Vin curve, it isn't even close to being flat. And it has a higher than desirable (IMO) voltage overhead. As you like to claim with your IS data, "truth is truth".

IMO, the Malkoff driver is still inferior, whether compared to a lower-powered driver or a higher-powered driver. My original point for showing the various graphs was to demonstrate what IMO "good" Pin vs Vin curves look like. "Apples to apples" in terms of matching power draw wasn't my intent nor necessary. Are you suggesting that somehow a higher power draw excuses poorer Pin vs Vin performance? In any case, here is a curve for a TLS TX3 head, which uses a cheap KD buck driver, modified for 1.4A output to a 2S2P MC-E. It has a flatter Pin vs Vin curve compared to the Malkoff, and the TX3's voltage overhead is only about 0.5V, which allows for 2xLi-ion. If the voltage overhead had been the same as with the Malkoff driver, 2xLi-ion would not be a good choice. The same high voltage overhead for the Malkoff makes 1xLi-ion (e.g., an IMR18650) a non-starter as well.

What can I say. For $125 for just the drop-in, I expect "perfection".

Since the Uniq tailcap has a parasitic draw of about 1mA and also has no momentary-on capability, I have little interest in it. Its relatively low amperage rating for the switch also gives me pause. You yourself rated it at 1.5A to 2A max here (specifically, the Uniq switch "may go pop" at 1.5A, and "don't think it will survive 2 amps at all"), and your data presented by bigchelis above in Post #6 shows that the Malkoff can draw ~1.7A. Call me cautious, but that does not look like a safe current draw relative to the rated amperage for the switch.

Yep truth is truth, I did have a UCVT go poof in the past, (sample base of 1) somewhere under 2 amps.

I am looking at your latest curve which shows pretty flat line regulation and I see that it really doesn't start to run full power until over 6 somewhere around 6.5V. It has a much different lead in curve or ramp up curve for the power draw and doesn't really turn on at 5V or less. So this doesn't do any good to run a MC-e module down to 5V either. but truth is truth and it is what it is. Do you have any curves of drivers in the 10 watt region that run from 5 to 12 or 13V to see how flat they are?

Everything comes with a price. The driver you just gave as an example would not really work well if at all below 6V on 2 CR123 batteries. The driver in the Malkoff will and does guarantee very close to full power output with the batteries sagging down to 5V based on my actual test results. So what you see as a issue of bad regulation or "poor" performance" I see as an important feature to help keep the light at full power at a lower voltage. Its a price to be paid in higher power consumption true, but everything has its trade off. As your chart so aptly demonstrates.

And we haven't even touched on how long these other drivers actually last. I have had some wonderlights that didn't last 5 minutes. So if the only real negative to the Malkoff is that at lower voltages it sucks up 1 extra watt of power, but keeps working like it should, I'll keep mine on hand and keep running it on 2 X rechargeable lithiums as it hasn't been an issue or a problem in real world usage.

(Still would like to see more 10watt range charts that start at lower voltages though).

MrGman said:

Yep truth is truth, I did have a UCVT go poof in the past, (sample base of 1) somewhere under 2 amps.

I am looking at your latest curve which shows pretty flat line regulation and I see that it really doesn't start to run full power until over 6 somewhere around 6.5V. It has a much different lead in curve or ramp up curve for the power draw and doesn't really turn on at 5V or less. So this doesn't do any good to run a MC-e module down to 5V either. but truth is truth and it is what it is. Do you have any curves of drivers in the 10 watt region that run from 5 to 12 or 13V to see how flat they are?

Everything comes with a price. The driver you just gave as an example would not really work well if at all below 6V on 2 CR123 batteries. The driver in the Malkoff will and does guarantee very close to full power output with the batteries sagging down to 5V based on my actual test results. So what you see as a issue of bad regulation or "poor" performance" I see as an important feature to help keep the light at full power at a lower voltage. Its a price to be paid in higher power consumption true, but everything has its trade off. As your chart so aptly demonstrates.

And we haven't even touched on how long these other drivers actually last. I have had some wonderlights that didn't last 5 minutes. So if the only real negative to the Malkoff is that at lower voltages it sucks up 1 extra watt of power, but keeps working like it should, I'll keep mine on hand and keep running it on 2 X rechargeable lithiums as it hasn't been an issue or a problem in real world usage.

(Still would like to see more 10watt range charts that start at lower voltages though).

Click to expand...

Of course the driver doesn't turn on at 5V or less. Why should it? The TX3 graph hits full regulation at ~7V because the head is driving a 2S2P MC-E at 700mA per core, which has a Vf of about 6.5V. It is a buck driver and thus it isn't going to do any regulating at 6V or less. I provided no data suggesting that the TX3 driver can't run below 6V, so your conclusion that the TX3 driver "would not really work well if at all below 6V on 2 CR123 batteries" is premature and not based on any facts I provided. In fact, the AX2002 buck IC used in the TX3 driver is rated from 3.6V to 23V.

Again, your new point about driver quality/life is irrelevant wrt the specific examples I provided. I agree that driver reliability is critical. But the whole point was to show what a "good" buck driver Pin vs Vin curve looks like. I've done that. And you've set up a false argument anyway. The choice doesn't have to be between a reliable driver that doesn't have a flat Pin vs Vin curve vs. an unreliable driver with a flat Pin vs Vin curve. I ask again: Do you really seem to believe that a reliable buck driver with a flat Pin vs Vin can't be done for 5V-13V at 2.4A? As for the reliability of the driver examples that I did provide, the SOB1000 is a well-respected driver from the Sandwich Shoppe. Yes, the DX6090 uses a cheap driver from Deal Extreme. Many have recommended it as a low cost alternative and in my experience it uses a reliable driver (though far less efficient than desired). The TX3 driver is the same one used in bigchelis's recent nailbender Mag mod that you apparently so coveted. As with the Uniq tailcap, your inconsistency is showing.

You keep asking for more and more information which is not relevant. The whole point is I've given 3 examples of flat Pin vs Vin curves. It can be done and it has been done. The Malkoff does not show flat Pin vs Vin behavior. You can spin it anyway you like (it's not a defect, it's a feature -- yeah right) to defend some apparent sacred cow or altar you are worshipping on, but the fact remains that the Malkoff driver generates an excess 1W of power, which cuts run time.

You can do the test you desire yourself. Your bud bigchelis has a moddoo triple XP-E (wired in parallel so that Vf should be around 3.5V, which you can check for yourself anyway) driven by a 2xSOB1500 sandwich. Test it for Pin vs Vin and see what it does in comparison to the Malkoff MC-E driver.