Reviewer's Note: I am very backlogged with lights, so expect less detail than typical in my upcoming reviews. I will prioritize analyses over text descriptions.
The U21 is compact thrower light from Manker, featuring the high-output but compact XHP35 High Intensity (HI) emitter. Coupled with larger reflector, this light should produce excellent throw. Supports a standard 26650 Li-ion battery (18650 will also work in the light).
Manufacturer Reported Specifications:
(note: as always, these are simply what the manufacturer provides – scroll down to see my actual testing results).
- LED: Cree XHP35 HI
- Output / Runtime: Turbo: 1300 Lumens / 1.25 Hours, High: 650 Lumens / 3.1 Hours, Medium 2: 300 Lumens / 5.2 Hours, Medium 1: 100 Lumens / 12 Hours, Low: 15 Lumens / 100 Hours
- Peak Beam Distance: 700 Meters
- Peak Beam Intensity: 124,000cd
- Working Voltage: 2.8-4.35V
- USB Charging Current: 2A (overcharge and discharge protection)
- Circuit Driver: PFM/PWM Synchronous booster intelligent conversion
- Reflector: Aluminum Smooth Reflector
- Lens: Toughened Ultra-clear Double Glass Lens with Anti-reflective Coating
- Impact Resistance: 1.5M
- Switch type: clicky switch
- Aero-grade aluminum alloy
- Surface treatment: premium Type III hard anodizxed anti-abrasive finish, thickness >50um
- Feature: Anti-Roll Rugged Design, Cooling Slot of High efficiency, Lanyard, Lightweight, Pocket Clip, Power Indicator
- Battery Quantity: 1 x 18650 / 26650 battery (not included)
- Waterproof Standard: IPX-7 Standard Waterproof (Underwater 1m)
- Dimensions: Product weight: 0.290 kg, Product size (L x W x H): 14.80 x 5.90 x 5.90 cm / 5.83 x 2.32 x 2.32 inches
- MSRP: ~$65
Inside the cardboard box you get the light, an anti-rattle tube for 18650, a very short micro USB-charging cable, decent little wrist-strap and manual. There is no included battery.
All dimensions directly measured, and given with no batteries installed:
Manker U21: Weight 294.4g (391.5g with 26650 battery), Length: 149.1mm, Width (bezel): 59.1mm
Foursevens MMU-X3: Weight: 172.0g (264.2g with 26650), Length: 135.8mm, Width (bezel): 46.0mm
Foursevens X10: Weight: 156.9g, Length: 135.5mm, Width (bezel): 46.0mm
Lumintop SD10: Weight: 117.6g, Length: 120.3mm, Width (bezel): 40.1mm
Olight R50: Weight 158.3g (255.4g with 26650 battery), Length: 133.0mm, Width (bezel): 42.0mm
Olight S80: Weight 162.5g, Length: 151mm, Width (bezel): 38.7mm
Skilhunt K26: Weight: 188.2g (301.9g with 26650 battery), Length: 163mm, Width (bezel): 44.1mm
The U21 is reasonably compact for a 26650 thrower light.
Anodizing is flat matte black, with no blemishes or flaws on my sample. Labels are clear against the dark background. Knurling is not aggressive at all, but overall grip is ok. Note that the light can roll fairly easily.
There is a single electronic switch in the head, with typical feel. There is a red LED that serves as a low-voltage warning feature under the switch (activates when <25% remaining).
Charging is done at micro-USB port opposite the switch, under a typical dust plug. Blue/red LEDs under the switch indicate charging status. Note the charger is a 2A charger, so is only suitable for 26650 cells.
Screw threads are square-cut, and anodized for tailcap lockout. A quick turn of the tailcap is all you need to lock out the light. The light can tailstand stably.
The XHP35 HI emitter is well centered, at the base of a smooth and deep reflector. This should produce great throw. Scroll down for beamshots.
Click the electronic switch to the turn the light on, press-and-hold to turn off.
When On, click the switch to cycle through the main output modes as follows: Low > Medium 1 > Medium 2 > Hi > Turbo. There is no repeating loop on the light, it simply stays at Turbo. There is mode memory, but you access it by a press-hold of the switch from Off. Otherwise, a single click will always activate on Low.
UPDATE: Manker informs me that the above was an issue on my engineering sample - shipping versions should automatically repeat through the regular output modes on successive clicks.
Blinking modes are accessed by a double-click of the switch (from On or Off). First mode is Strobe. Single click to advance to "breath flash", which seems to turn the indicator under the switch to solid purple (i.e., both blue and red LEDs light up). Click again to advance to SOS. There is a repeating loop for strobe modes, and a single click returns to Strobe.
There is no electronic lock-out mode that I can see. You can physically lock out the light by a twist of the tailcap.
For information on the light, including the build and user interface, please see my video overview:
As with all my videos, I recommend you have annotations turned on. I commonly update the commentary with additional information or clarifications before publicly releasing the video.
There is no apparent sign of pulse width modulation (PWM) at any level. The light appears to be flat-stabilized, and is flicker-free at all output modes.
Strobe is a very fast tactical strobe of 22.4 Hz, but with reduced On time (i.e., it spends most of the strobe duty cycle off, consistent with many super-fast strobes).
Since the switch is electronic, there needs to be a standby current when the tailcap is connected. I measured this as 7uA. For a 4500mAh 26650 battery, that would translate into over 73 years before the cell would be fully discharged – and so, is not a concern.
Note that you can lock out the light by a simple twist of the tailcap.
Because the light uses a USB charging cable, I was able to take direct measures of the charging parameters using my Xtar VI01 "USB Detector" (basically a specialized USB current/voltage meter). There are many of these on the market now, and this model was favorably reviewed by HKJ here.
For charging tests, I left the USB detector in place for all readings. Note that the voltage reading on this device refers to the input voltage (i.e., from the USB port). I used an Olight 4500mAh 26650 battery.
Initial charging current was 1.64A, at 5.53V input voltage.
By just after 2 hours into the charge, current reached its maximum at 1.94A, at 5.59V. Current started to slowly drop off from this point.
At 3 hours and 10 mins, current was 0.20A, 5.28V
A complete charge cycle (for a 4500mAh cell) took about 4 hours, with the LED showing blue for termination (and 0A on the detector).
For white-wall beamshots below, all lights are on Max output on an AW protected 18650 battery. Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.
All my output numbers are relative for my home-made light box setup, as described on my flashlightreviews.ca website. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.
I have devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lightbox values to Lumens thread for more info.
Throw/Output Summary Chart:
My summary tables are reported in a manner consistent with the ANSI FL-1 standard for flashlight testing. Please see http://www.flashlightreviews.ca/FL1.htm for a discussion, and a description of all the terms used in these tables. Effective July 2012, I have updated all my Peak Intensity/Beam Distance measures with a NIST-certified Extech EA31 lightmeter (orange highlights).
Max output and throw for the U21 are close to the Manker specs. This is a lot of throw for such a small size.
Again, lumens estimates are pretty close to the Manker specs across the board. See runtimes below for more info.
All my current runtimes are done under a cooling fan.
The U21 shows a multiple-step-down pattern on all levels, so you are never left without light by surprise. Overall efficiency seems good for the class, and the light is very flat-stabilized.
Note there is a quick initial step-down on Turbo at ~3 mins into the run. You can restore max output by turning the light off/on.
Note also that there is also a red LED low voltage warning feature under the switch, as the battery runs down.
The light uses an electronic switch, and therefore requires a stand-by current when fully connected. However, this drain is completely negligible (7uA), and well below the self-discharge rate for Li-ion. You can physically lock-out the switch with a simply tailcap twist, breaking this current and preventing accidental activation.
The built-in charging feature is capable of charging at up to 2A. Only a small micro-USB cable is supplied, so you need to use your own 2A-rated AC charged.
No 26650 battery is supplied.
While the U21 can also run on standard 18650, I recommend you use a good quality IMR cell on Turbo. Also note that the charging feature only supports 26650 (due to the high 2A charging rate). And a 18650 will rattle inside the light, even with the optional insert.
Light can roll easily.
The U21 lives up to its billing – it is a sturdy throw light with a very focused beam, great runtime (thanks to the 26650 support), and an excellent 2A USB rapid charger.
The Interface is pretty basic, but serviceable enough once you learn it. Mode spacing is decent overall.
The U21 doesn't come with a battery, but any standard 26650 Li-ion will work fine – and can be charged with the good 2A charger. Note you will need to supply your own 2A-rated AC adapter. You can also run the light on 18650 with the anti-rattle insert (which is only partially effective). I recommend you stick with high-quality IMR cells if intending to run on Turbo with 18650. And of course, the 2A charger is not suitable for lower-capacity 18650.
The beam profile is very good, with minimal artifacts for such a tightly focused hotspot. Also had a broad (but dim) spillbeam.
Performance-wise, you get very good efficiency and output regulation (i.e., flat-stabilized, with multiple step-downs as the battery is exhausted). No sign of flicker anywhere.
The build is about typical for Manker – decent, but nothing extraordinary. The light lacks some of the premium extras (i.e., battery, AC adapter, holster, etc). But if these don't matter to you, there is a lot of performance here for the price. I am sure it will be popular with throw fans.
U21 provided by Manker for review.