Malkoff M60W On 2x 17500

This is my daily carry but I've never performed a runtime test. I've heard it suggested that the M60 will get 45 minutes of runtime on two 17500's but that didn't seem to be consistent with my experience. I don't know how many amps the M60W is drawing at 8.4v and I don't know if it draws a little less than the M60 does. I do know the M60W is rated at 170 lumens whereas the M60 is rated at 235, though the practical differences in throw seem to be more or less negligible to me.

So... the M60W ran for 2 hours 4 minutes continuously on 2x 17500 experiencing only a slight reduction in brightness after 1 hour. It was at all times more powerful than the M60LL or P60L running on the same batteries. As expected it also gets quite a bit warmer when sitting on the table than it does when held in the hand.

The interesting thing to me is that the AW protected 17500's are rated at 1100mah each for a total of 2.2 theoretical amp hours. While I can't say how efficient this stacking is because I don't know the M60W's draw at the concerned voltages the max potential runtime based on a 750mah draw and the 2200mah capacity would be 2.9 hours. Since there are more variables to consider than just those and I'm getting closer to 2.1 hours it's plain to see that the M60W's driver is good at getting the most out of the available cells. Off the cuff I'd guess that the M60W would get around 3.5 to 4 hours off 3x CR123 and that may go higher if the drop in voltage corresponds to a significant drop in draw.

Your calculations are flawed!

2 x 1100mA cells in series will still only give you 1100mA, just at a higher voltage.

In series, if it was not regulated. I'm no expert on flashlight electronics but if what you say was true then the M60W would not have been able to run for 2 hours and 4 minutes. 1100mah/750ma draw is only 1.46 hours of runtime. 750ma corresponds to what the M60W draws at 6v and it is likely drawing more than that at 8.4v. So the capacities are unquestionably stacking in some fashion because of the driver.

Correct because of the driver which will draw less current at higher voltages.

But stacking (in series) 2 x 1100mA batts will not give you 2.2amps. If you connect a hundred 1100mA batts in series you will still only have 1100mA.

If you want to calculate runtimes you really need to measure the current draw from the cells.

GreyShark said:

snip..... 750ma corresponds to what the M60W draws at 6v and it is likely drawing more than that at 8.4v. snip..........

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No it should be less at 8.4 volts

London Lad said:

No it should be less at 8.4 volts

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So it works counter to my direct drive hotwires then? Slurping up more milliamps to compensate for a drop in voltage or just picking at its food when the voltage is high? I was under the impression that it was acting as a governor on the rate of current consumption while higher voltages just made it run brighter.

Still, if the light is performing as if it had access to 1575mah of capacity instead of 1100mah I'm not going to begrudge the mechanism by which it achieves that.

If you want to calculate runtimes you really need to measure the current draw from the cells.

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That's why I do tests instead of perform calculations, I don't have the proper tools to measure draw accurately. Plus it has the benefit of demonstrating for sure exactly what my real world set up will do. My calculations would be all goofy because I don't have a thorough grasp of the electronics but any fool can watch a light and time it till it turns off.

OK I have just run a quick test on a M60. It draws 0.6 amps from 2 Li-Ion cells and 0.85 amps from 1 Li-Ion cell.

The converters in these lights are attempting to supply the led a constant current and / or voltage over a range of battery voltages, in order to keep it at a constant brightness.

Amps x volts = watts.
So if an item draws 2 amps when fed with 4 volts and 1amp when fed with 8 volts it's consuming the same power, 8 watts.

It gets more complicated because of the many variables such as voltage sag and differing converter efficiency at different input voltages etc tec.

I strongly recommend that you get a cheap multi meter, you can buy them for $10. They are junk but even the cheapest ones will let you measure volts and amps and see what's going on. Don't forget that when you measure volts you connect the meter in parralel with the supply and when meassuring amps connect it in series with the load.

Have fun!

BTW I agree that there is no substitute for a real live runtime test but they can get boring sometimes.

That's great runtime. I'm at a loss to describe the drop in brightness you mentioned, though. Should stay the same 'til the batteries protection kicks in.
I tested my M60W at 1hr. 4min. 50sec. on 2 AW R123s, and would have only expected the 17500s to run ~1.5hr.
btw, mine draws 550mA on fresh Li-ion batteries regardless of size/capacity, but that increases as the batteries' voltage drops.

GreyShark said:

So it works counter to my direct drive hotwires then? Slurping up more milliamps to compensate for a drop in voltage or just picking at its food when the voltage is high? I was under the impression that it was acting as a governor on the rate of current consumption while higher voltages just made it run brighter.

Still, if the light is performing as if it had access to 1575mah of capacity instead of 1100mah I'm not going to begrudge the mechanism by which it achieves that.



That's why I do tests instead of perform calculations, I don't have the proper tools to measure draw accurately. Plus it has the benefit of demonstrating for sure exactly what my real world set up will do. My calculations would be all goofy because I don't have a thorough grasp of the electronics but any fool can watch a light and time it till it turns off.

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Malkoffs have a constant current driver. My M60 draws around .8A at 6V and around .610A at 8.4V. The brightness remains the same because the current to the emitter is kept constant by the driver. That's what 'regulated' means. The driver will draw less current off of higher voltage and more current off of lower voltage.

M60__from Regulated power supply,
Volts___amps___watts______,
3.0_____0.09____0.27__,
3.2_____0.22____0.70__,
3.5_____0.38____1.33__,
3.6_____0.51____1.84__,
3.8_____0.66____2.51__,
4.0_____0.86____3.44__,
4.2_____1.08____4.54__,
4.5_____0.85____3.83__,
4.7_____0.88____4.14__,
5.0_____0.80____4.00__,
5.5_____0.74____4.07__,
6.0_____0.69____4.14__,
7.0_____0.60____4.20__,
7.9_____0.56____4.42__,
8.0_____0.53____4.24__,
8.4_____0.50____4.20__,
8.5_____0.49____4.17__,
9.0_____0.47____4.23__,
9.5_____0.45____4.28__,

As the voltage goes up the current draw went down keeping power mostly constant to the LED from the regulated driver inside the module. Your M60 with 2 17500 batteries under load from 8.4V down to 7V draws less current than using 2 CR123 primaries, that's why the batteries last longer. this information has been posted by myself and numerous others, it is not new. As London Lad stated 2 batteries in series still have the same current capacity as one, the voltage changes and therefore LED type lights with regulated drivers take advantage of that and draw less current.

If the battery has 1.1 ampere hour rating and the current draw is 0.5 amps than the consumption becomes 1.1 divided by 0.5 to be over 2 hours. In reality your batteries are probably good for a 1.4 ampere hour rating. No mystery here. Run times showing this effect have been posted by a lot of people.

Greyshark you need to do a lot more research if you still have no understanding that LED light modules with regulated driver circuits are nothing like an incandescent lamp filament in how they draw power and make light.

Owen said:

That's great runtime. I'm at a loss to describe the drop in brightness you mentioned, though. Should stay the same 'til the batteries protection kicks in.

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It could have been atmospheric. I was judging brightness from throw and it seemed to lose a little brightness at 200 feet after an hour. This is also the rainy season where I live and it's entirely possible there was more water in the air after an hour had elapsed than when I initially turned the light on. I'll test again on a day it hasn't been raining and compare the results.

Malkoffs have a constant current driver. My M60 draws around .8A at 6V and around .610A at 8.4V. The brightness remains the same because the current to the emitter is kept constant by the driver. That's what 'regulated' means. The driver will draw less current off of higher voltage and more current off of lower voltage.

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Amps x volts = watts.
So if an item draws 2 amps when fed with 4 volts and 1amp when fed with 8 volts it's consuming the same power, 8 watts.

It gets more complicated because of the many variables such as voltage sag and differing converter efficiency at different input voltages etc tec.

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That probably explains my confusion. I have heard "constant current" before but I wasn't thinking in terms of of watts. Anyway thanks for the feedback, I appreciate having a better understanding of what's going on inside my drop ins.

It just finished raining tested the M60W on a set of freshly charged 17500's and found that it was throwing the same as it was 1 hour into yesterday's test. Unless the M60W itself has declined in output I think it's safe to say that the apparent drop in out was driven by weather effects. I'll still have to test again on a dryer day.

In the meantime I'm doing a runtime test on the M60W driven by 3x CR123. I'm only half an hour into the test but to my eye it's as bright as it is on 2x 17500.

Just to gain a little bit of clarification- can I ask anyone who is willing to answer what kind of runtime I should expect for an m60W on 2 x 17500's? 2 hours sounds like a killer runtime to me, but do you think there is a chance you may have an overachiever malkoff? I think I can recall hearing that an hour and a half was a reasonable runtime for the m60W on 17500's, so should I expect something in the ballpark of 1.5-2.0 hours, perhaps an hour and forty minutes or so? :candle:

From a capacity standpoint, do two 17500's have roughly 33% more capacity than two 16340's?

Sorry for my newb questions, but all of the milliampre-watt-hour flux-capacitor talk is greek to me, although it sounds like it would be some cool knowledge to have!

My results seem to coincide pretty closely with the chart MrGMan posted so I would go out on a limb and suggest that 2 hours of runtime on 2x 17500 is probably typical.

Sorry for my newb questions, but all of the milliampre-watt-hour flux-capacitor talk is greek to me, although it sounds like it would be some cool knowledge to have!

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I know what you mean. I just needed a light that could fit in my pocket and throw a beam from my front door to the end of my driveway... though suffice it to say my driveway is considerably longer than most... I didn't really intend for this to become a hobby, or that I'd end up with serious money and time invested into it. I've been trying to artfully avoid learning too much about the electronics side of LED's.

I got about 2.5 hours of regulated runtime with the M60W on 3x CR123. After that it dropped into direct drive with output diminished to about what a P60 incan puts out. It's still running after 4 hours though the light is pretty weak now, somewhere between that P60 level and an incan MiniMag.

JonM, they have about 50% greater capacity(1100mAh vs. 750mAh).

Don't expect to match that runtime. It should be hitting just over 1.5hr. Theoretically, 2 hours is not only not typical, but not even possible(unless you believe in 100% efficient circuits and cells whose voltage doesn't drop), given the current draw vs. mAh rating of the cells. A combination of low Vf emitter, and overachieving cells, perhaps. Someone else recently commented that their AW 17500s have always performed well beyond their capacity rating, and I don't doubt it, having always gotten great performance from mine. It may well be just that simple.
Now I want to do a runtime test with my own M60W and 17500s out of curiosity, to see if it will match GreyShark's. That will be sweet if they do.
I'm planning to use 2xAW18500(1500mAh) on it soon, but was only expecting a bit over 2hrs. from them, since they're rated at double the capacity of the R123s.
Certainly won't complain if they perform beyond spec, though!

JonM said:

Just to gain a little bit of clarification- can I ask anyone who is willing to answer what kind of runtime I should expect for an m60W on 2 x 17500's? 2 hours sounds like a killer runtime to me, but do you think there is a chance you may have an overachiever malkoff? I think I can recall hearing that an hour and a half was a reasonable runtime for the m60W on 17500's, so should I expect something in the ballpark of 1.5-2.0 hours, perhaps an hour and forty minutes or so? :candle:

From a capacity standpoint, do two 17500's have roughly 33% more capacity than two 16340's?

Sorry for my newb questions, but all of the milliampre-watt-hour flux-capacitor talk is greek to me, although it sounds like it would be some cool knowledge to have!

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Owen said:

JonM, they have about 50% greater capacity(1100mAh vs. 750mAh).

Don't expect to match that runtime. It should be hitting just over 1.5hr. Theoretically, 2 hours is not only not typical, but not even possible(unless you believe in 100% efficient circuits and cells whose voltage doesn't drop), given the current draw vs. mAh rating of the cells. A combination of low Vf emitter, and overachieving cells, perhaps. Someone else recently commented that their AW 17500s have always performed well beyond their capacity rating, and I don't doubt it, having always gotten great performance from mine. It may well be just that simple.
Now I want to do a runtime test with my own M60W and 17500s out of curiosity, to see if it will match GreyShark's. That will be sweet if they do.
I'm planning to use 2xAW18500(1500mAh) on it soon, but was only expecting a bit over 2hrs. from them, since they're rated at double the capacity of the R123s.
Certainly won't complain if they perform beyond spec, though!

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Without going into the capacity debate for RCR123's (a very long story), there have been repeated citations of Malkoff M60 runtimes on 2xAW RCR123's of ~40-50 minutes, and also repeated citations of M60 runtimes on 2xAW 17500's of 1 hr 45 minutes (which has been my experience with my AW 17500's as well).

Runtime with 2x17500 = ~ twice the runtime than with 2xRCR123.

This thread is a good start on the issue:
https://www.candlepowerforums.com/threads/194879

Hope this helps,

Hey guys,

Thanks for all of your great and informative replies, esp. that link to the Malkoff runtimes! Any runtime at or over 1.5 hours is just fine by me; something closer to 2 hours would just be icing on the cake. Its cool to know that the M60W will go into unregulated output on primaries for extra-long runtime, that is new info for me. I have a 9p running 17500's with a M60W myself, and I just wanted to get an idea of what to expect as far as a full runtime (haven't gone through the batts in one sitting yet). I am impressed that adding an extra inch and a half or so to the 6p's length can double or nearly double run time, or at least significantly increase it- it seems like a little bit of extra room goes a long way. In the same vein, I have heard that using 18500's in a bored 9p gives you an extra half hour or so of runtime, which is even more impressive, especially considering that you are only adding an extra millimeter of circumferential space or so.

Would I be on the right track to guess that significant gains in runtime complement small increases in battery diameter simply do to the squaring factor present in the cylindrical volume formula (H * pi*R ^2 or something like that)? I know that even though they are only slightly thicker, 18650's have significantly more runtime than 17670's, which leads me to suspect that it may be due to the squaring factor I mentioned. Of course this is all based on intuition and I could be hopelessly wrong about the whole thing...:duh2:

I don't mean to derail the thread if this is too off topic- I'm just a little curious about the whole battery capacity thing and am wondering if any of the experts could give me a brief, for-dummies version. I think with a little use of the search bar I may just stumble on a thread that answers all of this elegantly.

JonM said:

Its cool to know that the M60W will go into unregulated output on primaries for extra-long runtime, that is new info for me.

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It's new to me, too... which is why I'm doing these tests in the first place, I want to know what my stuff is capable of in the real world. Speaking of which the M60W has run continuously for 12 hours on 3x CR123. I'm stopping this particular test because the output has grown very faint and I need that light back but it looks like it could have went a while longer as long as you were satisfied with the low output. I was surprised, I would have thought the 3 cells would hold the voltage high enough to remain in regulation long enough to quite nearly deplete the cells giving the M60W only a very brief and very dim run in direct drive.

I am impressed that adding an extra inch and a half or so to the 6p's length can double or nearly double run time, or at least significantly increase it- it seems like a little bit of extra room goes a long way.

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I'm still very fond of the 6P but the 3 cell form factor is my favorite due to its unique capabilities. Even though I own a C3 Centurion I'd never give up my 6P w/ A19 extender as it has its own particular benefits and makes an awesome platform for experimentation.

In the same vein, I have heard that using 18500's in a bored 9p gives you an extra half hour or so of runtime, which is even more impressive, especially considering that you are only adding an extra millimeter of circumferential space or so.

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I'm very interested in the 18500's but I just can't get over the thinning in the tailcap area. I justify my reluctance by saying that the standard diameter body is better for use AA's. I really wish SureFire would just create a new generation of rechargeables that were designed for 18mm cells with slightly thicker material around the tail section and slightly larger tailcaps to fit. I realize that the tail of a bored C series light isn't just going to fall off under ordinary use but it's not the ordinary stuff I'm concerned about. Maybe one of the days I'll have to do some side by side destructive testing of a bored and non-bored 6P.

Would I be on the right track to guess that significant gains in runtime complement small increases in battery diameter simply do to the squaring factor present in the cylindrical volume formula (H * pi*R ^2 or something like that)? I know that even though they are only slightly thicker, 18650's have significantly more runtime than 17670's, which leads me to suspect that it may be due to the squaring factor I mentioned. Of course this is all based on intuition and I could be hopelessly wrong about the whole thing...:duh2:

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My gut feeling is that there's a certain amount of overhead in the design of a battery and whatever these key components are they take up space that could be used for the goop that actually yields power. A smaller cell would have a greater proportion of its total volume dedicated to this overhead whereas a larger cell would proportionally have more goop compared to its overhead. I haven't actually tried to measure the volume and capacities of various sized cells and work out the relative power densities.

I don't mean to derail the thread if this is too off topic- I'm just a little curious about the whole battery capacity thing and am wondering if any of the experts could give me a brief, for-dummies version. I think with a little use of the search bar I may just stumble on a thread that answers all of this elegantly.

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I don't mind at all, the whole purpose of starting this thread was to generate info on M60W real world runtimes and learn things I don't know. The search itself is a useful feature too but I don't really agree with the people who get especially insistent on its use at every turn. That philosophy would tend to suggest that a discussion forum's purpose is to eventually shut down because anything you might want to know is probably buried deep down in some archived thread. I've always felt a discussion forum should be for discussions. If I am not interested in a particular discussion I just don't get involved. Heck, if I was strictly relying on the search function I'd still have a backwards idea of how the M60W's regulation works.

If anybody out there does have an M60W and a 2x 17500 host to power it I'd like to hear your runtime results too.

JonM said:

I'm just a little curious about the whole battery capacity thing and am wondering if any of the experts could give me a brief version.

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It is very interesting stuff. I'm no expert, but here goes...

It definitely goes a lot further than the volume = (pi)(r^2)(L) calculation. Here's an abbreviated version, and I might have even forgotten other relevant factors:

• 16__0 = ~16.4 mm, 17__0 = ~16.9mm, 18__0 = ~18.3 mm. As you can see, the posted diameters are not all as they initially seem, '18mm' cells gain more than 1mm OD, leading to more capacity gain than would be calculated by going off their 'nominal' size.
• 3x16340 = 3 top button areas, 3 crimp seals, 3 PTC's, 3 PCB's, 3 steel bottom plates, all of which displace useful volume
• 2x1_500 = 2, 2, 2, 2, 2. Less stuff, more chemistry.
• More manufacturer dishonesty in the extremely competitive RCR123/16340 field. Capacity claims get most inflated in this area, up to !~70%! inflation, claims are less inflated in other (larger) cell sizes.
• Draining cells at a specific rate that have more amp-hours, exhibit even greater amp-hours as they are being loaded at less 'C', as related to their initial capacity. For more info, see any of the battery shootout threads by Silverfox, and see how the RCR123's begin to lose out at high drains. This behavior is lessened in larger cells, as they have an easier time since they are not being run full-out with regards to their posted capacity (i.e. amperage loads calculated not in 'current' but with respect to their 'C'). Check out Mdocod's two guides as well for a much better explanation.

Hope this helps, I bet I didn't even get all the complicating factors.

Conclusions:

2x17500 has twice the capacity of 2xRCR123/16340 for only 50% greater length, and ~50% more capacity than 3xRCR123/16340 - less 'other stuff' in the boiler room, the usable chemistry is also driven at a lower 'C' because they have greater initial capacity.

2x18500 stomps 2x17500 because of considerably more outer diameter than first apparent - check the actual cell measurements, you're gaining nearly 1.5mm in OD by going up 1mm in 'nominal' diameter.:huh: