Review: Nitecore MH10 Cree XM-L2 1000lm USB Rechargeable Flashlight

A few weeks ago, I was looking around wondering what I should buy myself, since I haven’t had a new toy for a while now and I really wanted to treat myself. I wanted something that would come in handy, that I know I would use, and that would be durable. Remembering last year’s stormy summer reminded me that I should probably improve on my stash of cheap random AA-powered LED flashlights. They worked well enough, although more light would’ve been welcome. Having a source of light when the power’s out at night is fairly important, and it’s sure to come in handy for walking about outside, or fixing something up.

As a result, I did a little digging online and I came across Nitecore, a Chinese brand with relatively favourable reviews and quite high-powered units with quite positive characteristics. Of their units, I decided to settle on one of their smaller multitasking-hybrid (MH) series torches, the MH10.

The MH10 cost me just under AU$100, and offered a Cree XM-L2 (U2) LED with 1000lm output, four output levels, high quality optics and USB charging with included 2300mAh protected 18650 Li-ion cell. I felt that was a fairly compelling offer, since it is basically a 10W LED light you can fit in your pocket, that you wouldn’t need to buy special batteries or chargers for, and can always top up from a computer, phone charger or power bank. It seemed ideal for travelling – something I hope to be doing in the near future.

While some regular people might consider this expensive, true flashaholics are known to spend several times more on similar torches, whereas some other torches have completely “bogus” output claims and poor design that won’t last the distance or measure up.

Unboxing

I was really looking forward to receiving this one, but it was a bit late and I thought it got lost in the post. When it finally arrived, it was clear why the parcel was a bit late.

That green label indicates that the parcel was inspected by our customs agency on possible suspicion of illegal items. It’s just a torch, but maybe to their scanners, it looked like an illegal device – maybe a laser, or a weapon. Needless to say, they opened it and found nothing of concern – just like last time when the quarantine service opened up my ovenized crystal.

The item came in a matte finish colour cardboard hanger box, sporting the yellow and black branding prominently across the package. It advertises compatibility with 2xCR123 disposable lithium batteries or 1×18650 cell, which is included. It advertises the micro USB port which is used for charging, and includes a cable for charging. Four output levels are provided, from a Cree XM-L2 (U2) LED with a super-low setting allowing for 520 hours of run-time. The product is made in China and comes from SYSMAX Industry Co. Ltd, backed by a five year international warranty.

The side of the box provides some other figures, including a maximum distance of 232m, a peak intensity of 13,500 candelas, 1.5m impact resistance and 2m waterproof rating.

Despite being somewhat crushed in transit, the insides fared well, with everything neatly packing into a moulded clear plastic tray with their own branding.

Included is a one page fold-open A4 leaflet with one side in English and the other in Chinese. A Worldwide Warranty Service card is also included, although it seems a bit archaic.

Included in the bundle is a nylon case for the torch which has an eye for something to “clip” on, as well as a rear loop for belt mounting. As promised, a charging cable is provided, although it’s not particularly thick and its connectors feel a little cheap. It has a nice reusable velcro tie which is nice. In the zip-lock bag, they’ve supplied a wrist strap with sliding clip and relatively “puffy” padded strap, along with a metal “clip” which can be attached to the torch if desired. A spare USB charging port cover, and two rubber O-rings are provided as well, which shows some forethought as these might be damaged within the service life of the torch, so to have them provided from day one really gives it a premium touch.

At a glance, the body of the torch looks like countless other Chinese “tube” style torches with milled aluminium construction. However, this one does have some particular features that aren’t found on the cheapest of torches. For one, it’s clearly branded, so you won’t mistake it for something else. Secondly, the tactile mode button is made of tinted translucent rubber, which a blue LED shines through to indicate battery status amongst other features. The rear has the micro USB-B charging port and cover as well, along with a laser etched serial number on the head. Apparently the grade of aluminium used is harder than the average cheap torch as well.

From the front, it’s clear that this is a well designed torch. The front window appears to be glass, and has a slight tint at some angles suggesting it is coated with an anti-reflection coating similar to photographic lens elements, to optimize performance. The reflector is very smooth, and its also very well aligned with the LED such that when viewed end-on, the whole reflector is “seeing” the phosphor coated yellow surface of the LED evenly. All good so far.

If you’re wondering where the battery is, well, it’s pre-fitted inside the torch. That’s not a particularly usual way to ship a battery, but it is a protected type so shouldn’t be damaged even if the torch accidentally comes on during shipment. There’s a slight nick in the outer wrap on my battery, but nothing major. It’s rated at 2300mAh, which isn’t anything special – it would be much nicer if they shipped the 3400mAh cell with the torch as they do for the MH27 as it’s only a little more expensive but almost 50% more capacity for the same size. The battery is a nipple type.

The battery’s negative terminal also has the Nitecore logo pressed within it. The torch end-cap isn’t active to my knowledge, but houses a golden spring contact soldered to a PCB with an ENIG finish, which uses the outer ring and the body of the torch to carry the negative side current. I suppose this ensures better contact than just having some random spring sitting in the aluminium cap. The end seems to have some silicone grease on the threads and the O-ring to ensure waterproofness.

The head also can detach from the body, and shows a special positive terminal design against reverse polarity connection. It appears to need a nipple-type battery to make the contact on the positive side, so harvested laptop battery cells with flat tops probably will need some modifying. Again, a circular ENIG finish pad is used to connect to the body of the torch and there is an ample amount of silicone grease applied to the threads and O-ring seal.

One thing I particularly like about the end-cap is that there is no active electronics or buttons on it, and it has two slots drilled plus a U-channel in-between. This allows you to thread the strap in a way where it loops securely and exits without impacting on the flatness of the base. This torch happily stands perfectly vertical even with the wrist strap attached. Big plus points for this, especially when used for emergency room illumination.

It’s also nice that the metal body clip is an optional thing and not screwed on by default. Those who like to have a perfectly cylindrical torch can leave it off, while the others clip it on. However, the quality of the clip seems a little suspect in terms of the finish – there seems to be unevenness in the paint coating and two places have significant “chips” in the coating. It’s still physically sturdy though, but the top of the clip does potentially interfere with the USB charging port slightly.

There we are – the torch, fully configured and ready for use. The best part is, even with the battery, clip and strap, it doesn’t weigh very much.

It seems like a good choice to carry around with you all the time.

In Use

It’s a torch, so what’s there to say? Well, actually, there is quite a few things worth mentioning. I’ll mention some of the impressions I had of the torch in this section, whereas more specific comments with data will be presented in the next section.

The manual says that the torch has a patented battery level display using the LED that is accurate to 0.1v. It blinks out the full volts, pauses, then blinks out the 1/10th of a volt place when the battery is inserted and the cap is screwed on. Thus, 4.2v is represented as four blinks, pause, two blinks. This is a nice feature, but on the MH10, it feels a bit neglected as to get the battery status, one has to unscrew and rescrew the end-cap. On the higher-end MH27, there’s a button combination that lets you read the voltage without such hassle.

The power switch is a clicky pushbutton that is input into an intelligent controller of sorts. A short press from off powers it up in the last brightness level selected, whereas a long-press from off powers it up in the lowest brightness level. This is great, as if you don’t remember what brightness you had it on last, you won’t inadvertently blind yourself and destroy all your night vision capabilities. Toggling between brightnesses is achieved by holding down the button once it’s on. Special modes are reachable by double-clicking the button from off, which defaults into a strobe pattern. Pressing and holding the button allows you to toggle to SOS, and again for locator beacon. There is no memory of the last special mode used, so it always enters into strobe whenever special modes are accessed. In all, the user interface is very intuitive, and not hard to use at all.

Subjectively, the output was quite bright – but as bright as expected. It seems to be quite an honest output, although inspecting the manual carefully shows that the 1000lm output mode is only available for five minutes before the torch ramps down the output to prevent overheating. I suppose this is a reflection that thermal dissipation is a problem when running at such current levels, and is to be expected on such a compact unit. The fact it wasn’t quite listed upfront feels a little dishonest, but for most people, they probably won’t even need five minutes at a go, so it’s probably okay. The unit feels quite solid, although after running for a while at the highest setting, it did get quite warm to the touch reaching about 50 degrees C. Because it has a conductive body, the battery was also probably cooking at the higher temperature, which might shorten its lifespan.

During running, the power status is reflected by the LED which blinks slowly at <50% of battery and quickly when almost depleted. By the time it blinks quickly, the output is diminished and it seems that the torch no longer regulates its output and so the output falls along with the battery voltage. This is good in case of emergencies where every last drop of power and illumination is desired, but it also means that you probably shouldn’t use unprotected cells with the unit or risk having them overdischarged by accident. The torch does have some “shimmer” in its output when the voltage is just on the borderline of being completely depleted.

The power button is easy to accidentally activate, with no “lockout” features to prevent activation when in a bag. I suppose you have to take out the battery when transporting to insure against a flat battery.

Testing and Analysis

This is where it comes to the “crunch” of testing and analysing data to see just how good (or not) the torch is.

Luminous Flux Output

Sadly, I don’t have an integrating sphere and a calibrated sensor to use to determine the absolute flux, but we can still at least understand if the quoted figures are reasonable by consulting datasheets.

The unit claims to use a Cree XM-L2 (U2 bin) LED. According to the datasheet, the LED has the following specifications:

It’s rated for a minimum luminous flux of 342 lumens at 25°C and 300 lumens at 85°C when driven at the test-current of 700mA.

From the flux vs current graph, the luminous flux increases to 325% of its rated flux at 85°C when driven at 3A. That’s a pretty beefy amount of current.

However, according to CREE, the LED can be operated up to 3A at the most, and has a forward voltage of 3.3V (typical). Thus it’s a 9.9W LED, which is quite impressive.

Thus, at 85°C (which is a good approximation of real life operating conditions), we can expect the LED to have 975lm minimum. I suppose for marketing purposes, they round this up to 1000lm, which is probably okay especially if the LED can be kept below 85°C. I suppose at just turning on with the temperature at 25°C, the LED can muster up a minimum of 1111lm, so it’s fair. But it also means that other torches using the same LED claiming significantly higher levels of lumens are very unlikely to be genuinely capable of it.

The LED will operate up to a junction temperature of 150°C, but it’s likely to shorten its lifetime and reduce its output significantly. Best to keep it as cool as possible, although that might not always be possible in compact form factors. I suppose that explains why there’s the five minute automatic ramp-down of drive current to prevent overheating. I suppose that’s also why the MH27 is superior, as it claims to have thermal-feedback foldback of current, so it only reduces drive current if the temperatures actually require that, so when operating in cool conditions, the LED can have higher output, and in hotter conditions, the LED is less likely to be damaged by overheating.

At a drive current of 3A at 3.3V, considering a nominal 3.7V battery with some conversion losses, it is near-as-makes-no-difference 3A from the battery which is a load of 1 to 1.5C for most 18650s, making it quite taxing on the battery as well.

Colour Temperature

For flashlights, we really never get a choice, so we’re just saddled with what we get. However, it seems that my camera thinks it’s about 6650K, making it daylight coloured. You can see a hint of anti-reflection coating colouration in the photo taken slightly off-centre because the beam was just too bright for the camera to handle.

Run-Time

It seems some people are obsessed to this to the detriment of all factors, so lets take a look at runtime. The manual itself provides the following summary (along with their test methodology):

The first thing to notice is that the figures apply for a 2600mAh battery, but the torch is supplied with a 2300mAh battery. I suppose this might be to make its “on paper” figures compare better with their competitors, but it is a little deceiving if you didn’t pick up on the discrepancy in capacity.

To test this, I decided to use a red LED as a photodiode with my Keysight U1461A meter to log the photodiode output over time. For the high and medium levels, I had the LED right on the lens itself, thus the sensor saturated, so it does not give a proper result for the brightness decay over time. The point where the battery becomes depleted to the point the regulation stops is, however, clearly evident. The low output was tested with the LED sensor remote from the torch and is affected by noise and changes in positioning (because it was rested on the floor and vibrations caused some movement). I didn’t have the patience to test the lowest setting – there really isn’t much of a point.

At the high setting, the run-time achieved was 2.587 hours, which is significantly longer than the claimed 1.25 hours. This is because the torch reduced its output after five minutes at high power, and continued at the lower power throughout.

For the medium setting, we achieved 5.068 hours and the low setting achieved 24.76 hours. If we scale by the battery capacity difference (26/23), we get 5.729 and 27.989 hours respectively, which pretty much match the 6 and 28 hour claims.

The end of run characteristics show that the regulator “drops out” and the torch continues on basically apply the battery voltage to the LED. The brightness diminishes rapidly, and the low light continues on until the protection board on the battery cuts off the power at the last-possible point before battery damage. Using unprotected batteries is a bad idea if it can accidentally be left on, because even at 2.6v, the LED can draw about 100mA according to the datasheet’s Vf ratings.

I didn’t actually test the cut-off voltage of the protection board or the current draw of the torch on the batteries as the connections would be rather difficult to make reliably.

Output Reduction in High Mode

Noting the mistake in using the LED as a detector in saturated state, I decided to repeat the experiment for the high output mode to see if I can detect the output reduction after five minutes as claimed in the datasheet. The LED was kept in a state where it was detecting ~0.8v so it would respond linearly.

As promised, it appears that the reduction was indeed detected, and while watching the LED, a slightly bumpy stepping down of power is witnessed at the five minute mark. When powered up from absolute cold, the output is strong but diminishes continually, which I suspect is due to self heating of the LED junction under a continuous drive current of (approximately) 3A. At five minutes and over a period of just over one minute, the output scales back to about 57% of the initial output. I’m guessing the current has folded back to about 1.8-2A. Running this over a period of 18 minutes shows very stable output, indicating thermal equilibrium (with an ambient of 23°C), thus is a good “long term” high power output drive current choice. However, if you power the torch off and on using the button, it will enter another five minute period of high drive power, which resulted in less output than initially due to the fact the LED was already hot. If you continually toggle the torch on and off, you can probably have it run at the high current level all the time, however, the LED will get quite hot and potentially overheat. Again, this seems to show that the MH27’s thermal feedback design is probably a better safeguard than the crude time-based protection.

During testing, the case reached 50°C according to my IR thermometer (emissivity 0.9) which was a little warm to hold, but not so hot as to be impossible to hold. I didn’t test the actual current consumed because getting the connections on wasn’t so straightforward, and I didn’t want to damage the unit.

Output Flicker

In the case of some of my older dimmable LED torches, the dimming is achieved by a “hard” PWM which produces significant flicker and distorts moving objects causing stroboscopic patterns which can be a safety problem and also cause eye strain.

I used the LED as a detector, with my Picoscope 2205A to see if any such PWM patterns were visible in the output.

At the lowest setting, the output was relatively smooth with a tiny ripple on it.

At low, a 100Hz ripple was visible, but its amplitude was fairly small, and at no point did the LED reach zero output, so flicker is unlikely to be apparent although a small variation in brightness of ~10% is present. It suggests that the regulator has sufficient capacitance on the output to smooth its discontinuous output. This level is present in many LED bulbs and downlights even when running at full 100%.

At medium, the same ripple is visible with a similar amplitude.

At high, no such ripple is visible, although a very small waviness is evident. This means that this torch in all modes shouldn’t have evident flicker as hard-keyed PWM torches might. A good result.

Special Modes

I thought I’d also try and work out what the special modes were like as well.

The strobe mode is a rectangular wave at a 16.3Hz frequency with a 29.44% duty cycle. Nice and simple, you can expect the torch to run about 3.4 times as long as the full power rating in this mode.

The SOS mode flashes out the SOS morse pattern which takes about 13.9s. It does seem there’s a slight bug in the SOS pattern, where the spacing between the S and O is longer than the O and S. I would have expected them to be equal. The duty cycle was read out to be 40.43% (not sure how accurate it is) but with that, I’d expect it to run about 2.47 times as long as the full power rating.

The locator beacon pulses at 0.5Hz, and apparently has a duty cycle of 0.910% according to this trace. It’s probably not that reliable as it’s zoomed out to fit multiple pulses, so lets take a look at a single pulse:

The pulse length is about 17.85mS, in a 2000mS slot gives a duty cycle of 0.8925%. So pretty close to the above figure. I’d expect the torch to run about 112 times the full power rating in this mode. Definitely a good thing if you’re lost on a deserted island …

USB Charging

The USB charging current profile was measured with my home-made USB current shunt and the U1461A.

This was charging a freshly depleted cell, and initially a low 50mA trickle was applied indicating the cell voltage is likely to have finished below 3v. The charging has an initial spike which dips before returning to the CC regime, similar to some cheap Chinese power bank charge controllers (so I suspect it might be something similar e.g. TP4056). The charger seems to be configured for a lowly 500mA charge current, and the charging completes in 5 hours 55 minutes and 29 seconds, pretty much the six hours as advertised.

The terminating current was 57mA, which is a little low for 18650 cells (most like about 100mA), but at least there is termination. It’s likely the termination is fixed by the charge controller to 1/10th the CC current as advised previously by a reader.

The charger appears to be a linear charger, with just shy of 2500mAh delivered to the torch. In case you were wondering, it’s not likely that the cell is overcharged – the 2300mAh would have gone to the cell, leaving 200mAh which was spent over 6 hours to light up the charge LED and power other controllers – about 33mA. The battery itself could be slightly over 2300mAh as well, which is another possibility.

It’s a bit disappointing that they didn’t make the charging any faster. Most 18650 cells can easily cope with a full 1A charge current, others up to 2.4A. With higher currents, the charge can be completed in half the time or less, making for much more convenience. The downside, of course, is that some extra intelligence is needed to cope with charging from PC ports which are 500mA only and probably more heat will be developed by the linear charger. Moving to a more efficient switching mode charger would probably work well, but would mean a larger space dedicated to charger circuitry. I suppose those who need a fast charge can just swap in/out 18650 cells and buy a dedicated charger and set of protected cells (which, incidentally, Nitecore also produce).

Note that you cannot use rechargeable RCR123 batteries (the MH27 can), or recharge CR123/RCR123 batteries in the torch. In fact, I’m not sure why you’d even bother with CR123 batteries unless you were really desperate, as they are quite expensive and aren’t really suited for continuous high drain (as they’re more suited to pulsed cyclic high drain photographic flash applications).

Conclusion

Another product gets the Gough treatment, and this time, it’s one that I’ve purchased for myself. On the whole, the Nitecore MH10 seems to be well built, with simple intuitive controls, good quality LED and optics, flicker-free dim modes, inbuilt USB charging and comes with all the needed accessories. The flat tailcap and special lanyard thread design allows for the torch to stand on its end, which is great. The price is quite acceptable given the amount of light it throws out, and it’s pretty compact as well. The manufacturer claims to back it with a five year warranty.

Of course, every product has places where it can improve, and the MH10 package seems to be slightly let down by a few things. One is the inclusion of the 2300mAh battery, which is less than the 2600mAh battery on which the runtime figures are based on and less than the 3400mAh battery that the bigger and better MH27 “brother” gets. It also has a 5-minute “timer” based scale-back of the output to prevent overheating, so the 1000lm output isn’t constant, whereas the MH27 also suffers from this but uses a thermal feedback control to ensure it doesn’t scale back unless it has to. The MH10’s timed scale-back is also reset by turning it off and on, so a user could theoretically cause damage by continually powering it on and off to keep it in the high current regime. The USB charging is also rather slow at 500mA and of the inefficient linear sort, although compatible. The included clip has a few paint chips, and the cable felt a little thin and cheap. The battery level indication is also not accessible unless you remove the tailcap and re-fit it.

Of course, if you’re interested, you can always just buy a new 18650 battery, say a protected Panasonic 3400mAh cell, or get a few cells and an external charger. On the whole, it’s not a bad torch at all, and I quite like it.

But even better, maybe you’d just accept the slight increase in bulk and higher price and just go for the MH27 which gives you R, G, B LED modes, thermal feedback LED drive current control, the larger battery, and compatibility with RCR123 batteries as well. The MH27 was the one that was crowned with a Red Dot Design Award after all.