HP25 review - initial thoughts

Possibly I should start by saying I have been using twin-beam headlamps for a long time (over 9 years), both for caving and surface use, and I have developed some definite preferences, but, I think, not unreasonable ones.
Also, to save myself from using the wrong terms, I'm going to avoid talking about low/med/high/turbo, since for some as-yet-unexplained reason for this light they mean different things for the two beams.

Operation is simple, with one pushbutton per LED, and using brief presses of the appropriate button to cycle indefinitely through the power levels, longer presses for off/on, and an extended press to engage SOS on the spot beam. Button pressure is a decent ~1kg
I do like having indefinite sequences with turn-off needing a more deliberate long action, though the need to hold a button down to turn on did seem a bit unintuitive.
Since the buttons are covered by a shield when the head unit is rotated back into its bracket, the long press to turn on doesn't seem necessary to prevent accidental activation, but I suppose most users will adjust to it in time.

The headstraps attach fairly easily, though they do take a little bit of manoeuvring under the split bars on the battery box.
The battery box itself looks reasonable, with gold-plated springs and contacts, though I haven't given it any immersion testing.
The user instruction sheet suggests the O-ring on the removable part is replaceable if it eventually wears out or gets damaged, but looking at it, I'm not sure how easy that would be. That said, given that all the contacts are accessible on the slide-out battery holder, they should be fairly easy to clean if dirty or to pre-emptively lubricate if the box was eventually found to leak.

Now, onto the beams.
I'm afraid beamshots will have to wait, but I will post some in the post below this one when they are done. To be honest, I'm not sure how useful they would be - white wall shots might emphasise things which are rather less obvious in actual use, while in-use shots showing significant things like transitions between beam areas might be tricky.

The flood beam is slightly centre-weighted, and does have some minor artifacts.
Looking at a white wall, it is, to a first approximation a couple of concentric circles, with the inner circle being about 3/5 the size of the outer one, and slightly brighter, though not hugely so.
The outer circle has a fairly hard cutoff, though on my unit there is also a slightly off-centre halo of much dimmer light outside the outer circle, shifted towards top left (on bottom right, the halo edge touches the main beam edge).

Rough luxmeter results might give some perspective in terms of variation across the beam.
I made some readings with the light and meter kept at constant distance, set up so that the beam centre gave a reading of 100, with the light being rotated to measure output in various parts of the beam.
In my light, with the beam centre at 100, the output across the inner circle varied between 95 and 110, tending to be slightly brighter towards the edge, so is effectively flat. In the outer circle it was mainly around 60-70, so not drastically darker.

I suppose the acid test for flood smoothness for me is reading, and I found reading with the HP25 absolutely great - I didn't notice any unevenness at all in the area of the beam I use to read, and even further out I had to look and know what I was looking for to really see anything.
In outdoor use, even walking along a fairly uniform-coloured road and actively looking for issues, the inner/outer circle boundary only seemed to be a rather faint slightly brighter line, so essentially flawless.
The faint halo outside the main edge of the flood which was visible on a white wall was not obvious, but on my light it was most present at the top and left of the beam where much of the time there is little to be lit, and a fair amount of it overlapped the area where the rims of my glasses interrupt vision, so wasn't really somewhere I was looking anyway.

The overall width of the flood was OK, with walking typically using the headset tilted down two or three clicks to properly light the area about to be stepped on with the head at a natural angle.
It's a distinctly tighter beam than my original Zebralight, and I'm not sure I'd want it to be any tighter, but than having it just-wide-enough does give advantages in terms of intensity.

The spot beam is quite tight, with an even circular hotspot and a much dimmer local halo visible on a white wall, but at realistic distances outside, the spot just seems to have a somewhat softened edge and no obvious halo.
There is a fairly even low spill extending out to a sharp cutoff at a circular edge only a little outside the edge of the flood beam's inner circle.
Outside the centre, the spill intensity is something like 1% of the central intensity, which may not sound like much, but it still measures as brighter than the flood beam when the flood is running at half the power output.

Outdoors, the spot does light distant objects well, though if looking at distant objects, the edge of the spill on the ground can still seem quite bright.
In a twin-beam light it's arguably unlikely that someone would be using the spot beam alone for non-spot duties like walking, but apart from the spill area being slightly narrow and hard-edged, the spot is quite usable for general movement.

As beams to use individually, I think both are decent, but I'm not sure they're the perfect ones to run simultaneously. In particular, the reflectored spot beam with a naturally hard edge to the spill is maybe not ideal for mixing with a flood since the edge of the spot's spill does give a significant two-level nature to the combined flood at most flood/spot blends. A spot which had less spill and particularly a softer outer edge to the spill could be blended rather more easily.

One of my long-time personal favourite beam blends is flood-plus-a-touch-of-spot, with the spot helping to significantly increase the reach of the flood without consuming meaningful extra power and without taking away from the flood nature of the beam.
Especially with a tight spot, that would involve a spot:flood output blend of the order of 10:1 or more, but given the close power stepping and the lack of a low output setting for the spot, that's not a blend that is really accessible on a HP25, since even maximum flood to minimum spot gives a beam with serious spot content.

Regarding power levels, as might be predicted from the figures, the subjective difference between the 180/90/45 lumen settings wasn't huge.
The 4lm flood was perfectly usable for walking with, though as might be expected, it was close to the lower limit for fully engaging colour vision, and the difference between it and the 45lm setting was quite noticeable in terms of colour quality as well as general brightness.

There was no visible PWM at any power setting with either eye movements or illuminating moving objects, and later testing (see below) points towards the existence of a 'pure' linear regulator.

Now, on to voltages and currents.

With 4xEneloops, I got the following current readings in mA, checking out one beam at a time.


A swift check, measuring the current draw (in mA) from both 4 and 3 Eneloops with a luxmeter present showed no difference in output and slightly higher efficiency at the lower voltage with 3 cells. To get more information, I had to sidetrack a little to build a variable voltage PSU, having been without one for a while.

With the PSU, and setting the HP25 to 180lm output on the flood beam, it could be seen that the output of my unit was perfectly regulated down to an input voltage of 3v30, with efficiency rising slightly with decreasing voltage.
Below 3v3, the output declined roughly linearly until at 2v75 it was 10% of the initial level, essentially like an LED in direct drive, or direct drive with a little extra voltage drop.

In the graph below, the lux and lux/power figures are based on an arbitrary (though fixed) positioning of the HP25 and luxmeter, in order to show relative changes in output and efficiency.
To avoid having a large amount of essentially flat lines, the horizontal scale drops in 0.5V steps to the point where interesting things happen, and then in ~0.5V steps thereafter.

Decreasing the voltage further, the light kept running, though with understandably limited output as the voltage declined further, and somewhere between 2v2 and 2v1 it turned off.
At any point above the final turn-off voltage, output would increase back to previous levels if the voltage was increased.

Overall, the light behaved as would be expected from true linear regulation with the benefit of buck conversion for input voltages in the normal operating range.
When someone opens a unit up (I'm keeping mine intact for long-term testing) it would be interesting to see if the peak current observed (700mA) is the actual LED current on the '180lm' setting.

in line with having linear regulation, there was a different dropout voltage for the different outputs - while the 180lm setting dropped out of regulation at 3v37, the 90lm setting stayed on full output down to 3v09, and the 45lm setting to 2v99.
That does mean that even in the absence of any kind of low-battery indication, the user can get some idea if they're in the final stages of battery depletion if they cycle through the levels - if they do that and there isn't a difference between the 180lm and 90lm settings, then it's really time to change cells, or maybe switch to the 4lm level if that output is bearable and more runtime is needed.

Having the light run at full output with a 700mA draw at less than 0v85 per cell, and still pulling 100mA at 0.7V/cell would suggest that in real use, the mid-power runtime after it drops out of regulation might be rather short.

I'm running some tests for behaviour in the final stages of exhaustion with 4 and 3 cells at the moment - results in a few days.
If I was somewhere where I couldn't easily keep an eye on cell condition and above all I didn't want to be surprised, I might be tempted to try running off 3 cells and a dummy cell, which at the expense of losing 25% of the full-power runtime, might give give a much longer and smoother tail-off.

In conclusion, I do really like this light, and I have to give great credit to Fenix for producing a consumer-level twin beam light at a decent price.

I'd personally prefer to have a 4 levels for the spot beam as well as the flood, and power steppings changed to something like a constant x3, since that would open up the full beam-blending experience, something I really believe there's a significant potential market for.
Thinking of beam blending, a less-hard-edged spill on the spot (TIR optic?) would make blending rather more subtle - often with a blended beam one will be looking down at the ground, at the point where the outer spot and flood edges are hard to miss.

Some white wall beamshots to show beam shape, all done at identical scale:


Flood beam alone (normal exposure)
The 'inner circle' can be seen here, but the inner/outer boundary is only just noticeable in the real-world use I've done so far.


Flood beam, 2-stop overexposed shot to show offset halo outside main beam boundary.


Spot beam alone (note hard cutoff at edge of spill).


Flood and spot beams at equal lumen output.

The colour cast is likely to be down to the rather old camera trying to do auto white balance - the shots are really to show the light distribution across the various beams.

Quick note:

I received my hp25 yesterday, the culmination of great curiosity to see if the HP11 could be bested.


In short, the light lacks: efficiency of the HP11, battery flexibility (something lightweight and invisible, to enjoy the flood. Or something beefy (2 18650), to take advantage of either high for a full 9 hour work day), and much needed toggle switch that could toggle between flood and throw.


I tried one dummy cell with 3 1.2 volt NiMH, but this voltage is too low for the light. The HP11 allowed me to drag voltage to darn near 3.0 volts before going out of regulation (Florinche had 3.2 volts, I had about 2.9). I doubt one could get very long runtime on one 3.7 volt 18650 (running 530 ma). However, 2s 18650, two in series (7.2 volt nominal), draws 350 milliamps per cell, giving 180 lumens (nearly 6000 candela); while the hp11 two parallel (the safer 3.7 volts) draws 350 per cell, giving 277 lumens and nearly 8000 candella. This is, what, two-thirds the efficiency of the HP11, if the output doesn't suffer from 3.7 volts. The hp11 does draw about .510 using the 7.2 nominal volt setup of 2 18650 in series.


In my book, there is something not quite right with the efficiency with this light (compared to the HP11), could be the drivers or the led bin. This is obvious too from the specs, where, you get an extra 47 lumens at the expense of halving your runtime (133 lumen hp11 v. 180 lumen hp25).


The flood is great, however still uncomfortable to use when laying in bed to read. I was hoping the flood may help in painting, at times. For example, I was up on a step ladder cutting a ceiling line, where the throw of the 180 lumen setting works best, until the wall is about or under 18 inches from my nose. I cannot step backward, so switching to flood would avoid glare and allow a second type of light for inspections. However, with no toggle, is nothing short of impractical to switch back and forth with the current system.


At the expense of 530 ma (an unacceptable amount of runtime), the high flood increases the lux of the hotspot about %2 and the corona about %85. The 4 hour 180 lumen setting is about %50 higher lux than the HP11's 133 lumen (9.5 hour) lux; the corona is about the same size & the hotspot bleed allows the hotspot of about the same size; also, at this level, the coruna is about %25 brighter than the hp11. At 90 lumen setting, the hotspot is noticeably smaller than the hp11 and the lux at 1 meter is a little shy of 3000 (fine for arm lenth detail work, but not enough for paint inspection from 6 foot).


I got to run. Just not with this light.

The regulation threshold might vary between lights, but I would have expected it not to vary by a huge amount (LED Vfs seem to vary fairly little these days), and with 3xNiMH which aren't actually close to exhaustion, any variation would seem only likely to have any effect on the highest output setting.

With my light, the point where current consumption peaks/output starts to fall is essentially the same for both LEDS - on the 180lm setting (one LED run at a time) it is 20mV different for the flood and spot beams, and low enough on both to run with flat regulation through almost all the capacity of 3xNiMH cells.

Having done some end-of battery-life runs, except for the runtime drop, I'd lean towards 3 cells being better than 4, since even with 4 largely balanced cells (all discharged on a C900 then briefly topped up), 4 cells give a rapid fall once dropping out of regulation, then a fairly flat period which coincides with the weakest cell getting driven into reversal.
With 3 cells, the fall in output was rather more gradual, and it's unlikely that any cells would get driven into reversal if there were only 3.
I'll be taking my HP25 out to Slovenia for a month this summer, using it and loaning it, and given that we have plenty of solar juice up the mountain so runtime isn't a great issue, I'll probably lend it with 3 cells in to avoid people running it dead flat and risk stressing the cells.

uk_caver said:

The regulation thershold might vary between lights, but I would have expected it not to vary by a huge amount (LED Vfs seem to vary fairly little these days), and with 3xNiMH which aren't actually close to exhaustion, any variation would seem only likely to have any effect on the highest output setting.

With my light, the point where current consumption peaks/output starts to fall is essentially the same for both LEDS - on the 180lm setting (one LED run at a time) it is 20mV different for the flood and spot beams, and low enough on both to run with flat regulation through almost all the capacity of 3xNiMH cells.

Having done some end-of battery-life runs, except for the runtime drop, I'd lean towards 3 cells being better than 4, since even with 4 largely balanced cells (all discharged on a C900 then briefly topped up), 4 cells give a rapid fall once dropping out of regulation, then a fairly flat period which coincides with the weakest cell getting reverse-charged.
With 3 cells, the fall in output was rather more gradual, and it's unlikely that any cells would get reverse-charged if there were only 3.
I'll be taking my HP25 out to Slovenia for a month this summer, using it and loaning it, and given that we have plenty of solar juice up the mountain so runtime isn't a great issue, I'll probably lend it with 3 cells in to avoid people running it dead flat and risk stressing the cells.

Click to expand...

I will need to retest, since my three 1.2 volt NiMH failed to light up the light. Also, test to make sure that the lux level is the same with the lower voltage. I, yesterday, was just noticing less lux with lower voltage setups on both the hp11 and hp25. Naturally, this would need to be repeated many times, across various lights to be sure.

7.2 volts does creep me out. Partly due to balancing the 18650s & fear of over using the protected cells below their 2.8 threshold, & mostly due to fear of burning out the driver. Looking at most buck drivers, the voltage range is in either the 3.6 or the 7.2 volt range, not both. However, I have no real daily use for this light in the 4 AA format: 4 hours runtime (useless) or less lux than I need for 6 foot wall detail inspection. <The hp25 with 4AA might be okay for occasional/seasonal walking at night, or camping--provided the light isn't buried in some trunk or drawer when needed.>

uk_caver said:

The regulation thershold might vary between lights, but I would have expected it not to vary by a huge amount (LED Vfs seem to vary fairly little these days), and with 3xNiMH which aren't actually close to exhaustion, any variation would seem only likely to have any effect on the highest output setting.

Click to expand...

I think too, that I noticed the high output of the spot suffered some, when blasting Flood at 180 lumens and running off only one 18650. I will retest with lux meter, later. I have also noted this phenomenon with other dual head-off one battery pack designs I have built. The total output--depending on battery setup-- of the two beams on high together, may be lower than the sum output of each head, when run individually on high.

We are talking about reasonable currents, so some temporary connection mechanisms could involve meaningful voltage drops - voltmeter readings taken directly from the HP25 battery box contacts could be helpful to ensure that isn't happening.

On my HP25 it seems to behave basically as two independent lights would - the threshold for dimming (and peak current draw) happens at essentially the same voltage with both beams on maximum as with either beam on maximum on it own (3v35-3v37 according to my meter) and peak current seems to be the sum of the two individual peak currents, allowing for the fractional difference between the voltages for the two beams.

Given that, the only obvious mechanism for one beam affecting the other is via internal resistance of the power source and resistance of the connections upstream of the battery box terminals.

If the source voltage is high enough to keep the voltage going into the cable above the threshold despite those source resistances, then there shouldn't be any interaction between the beams.
If the source voltage isn't high enough then the beams will interact to some degree.

I almost missed to note the fact that the HP25 cable to the rear pack is upgraded from the HP11, adding a curly and subjectively feels beefier. This is important.

Still, I am seeing a 90 lumen per watt HP25 lamp, vs. the 133 lumen per watt HP11--on high/turbo. This is meaningful, since it means I would need to feed the HP25 10 to 16 NiMH AA's per day, while the HP11 will eat about 4. Perhaps, the xp-eV1's just aren't that good; Perhaps, xp-g2 with larger head and toggle switch is what is needed to satisfy me and bring the 90 lumen number up to the 133 number and the 180 number up to the 277 number; Perhaps, xp-e2, will bring up the lumen numbers to more acceptable efficiency levels................. Now, this isn't to say, that this light doesn't beat Coleman; just that this light does not as decisively blow a 25 dollar Coleman out of the water.

I did successfully get 3 NiMH's to work (using second wire to hot); I think at 650 ma. However, my first runtime test (180 lumen spot level) off one 18650 2500 mah cell, lost regulation only 2 hours into the test--at 3.3 volts. I will need to re-test with a fresher cell and with more connectors and less resistance. Then, need a runtime test on 3 cells on high.

I may need to help you out with picture for this review--compare the beam with the hp11 and tk35 (at 360 lumen for 7.5 hour off two 18650s).

-------------------------------------
<Opinion, and pondering this lamp's future use for myself.>
Nevertheless, it would work fine with 4 18650s on belt--probably about the same lamp efficiency at the DX.com lights that use xml t6. However, with my older crew, I think the output and lux of the HP11 would be a much better aid for their old, over 40 year old, eyes. I will need more time to see is this is true.... Now, if I were navigating strange caves, yes, I think running this light at full steam would give a better sense of the surroundings...Camping and hanging out, you cant beat flood, however, fuel lanterns work better than battery leds...Walking the neighborhood, flood with about 20 feet of throw--maybe best?..Woods hiking, might not be much different than caving, unless you like the challenge of navigation with only night vision, aided by 3 seconds of burst throw to see what is out in the woods.
</Opinion, and pondering this lamps future use for myself.>

Another option: I just tested a 6 volt agm (purchased for $6 from batteriesasap.com) ub645 (4.5 amp hour). The draw was .45 amp, so should get about 8 hours on 180 lumen on one side. 4 hours full monty.

.. This format option would consist of a battery fanny pack, cord inside shirt, and solder wires or rig two dummy cells into either side, use duct tape to make rain resistant. You should retain the 4 AA option, without cutting factory wires. The UB645 battery weighs about a 1.83 pounds, gets about 100 to 300 cycles (I think 100 deep, if I recall.). Advanced glass matt technology is better than just lead acid, and upright orientation isn't needed.

http://www.wnybatteries.com/index.php?main_page=product_info&products_id=728

http://www.apexbattery.com/ubc-ub645-battery-sealed-lead-acid-batteries-ubc-batteries.html

Form factor note, 18650 cut-off test, simple wall beam shot, and comparison to $9 xpg direct drive flashlight


*Another note about the form factor of the HP25: The hp25 light head sits closer to the forehead than the HP11 (zero spill/glare into the eyes from head, unlike many lights). But, this is problematic for people who must wear duct bill hats with their head lights. The duckbill cuts off half the downward light output of the hp25=less flood downward. Reasons to wear a duck bill hat under a light: to keep paint/grease out of the hair; hats make wearing a heavier light more comfortable, even unnoticeable; keep head warm; hide messy hair or baldness.


*So, I now confirmed it may be possible to make this a 2 parallel 18650 light with successful full workday runtime; however, an xpg hp11 would offer nearly 90 more lumens with greater runtime.


Second18650 runtime test with less resistance: 4 hours, roughly on one 2600mah 18650 off charger. I noticed it out of regulation 4 hours 30 minutes. I ran 3 hours and 20 minutes first evening, and 1 hour 10 minutes in morning. Though I was sitting beside light--apparently oblivious--, I was working on the laptop, so not at all sure of exact time of death. I would need to be using the light to be sure.




*Here is a simple white wall (blue wall) picture of the HP25 on Spot High:
https://docs.google.com/file/d/0ByvnKHNhvrTma1l6WVJkMDB0V2M/edit?usp=sharing


<Notice the bright and large corona (I recall 250 lux), about the size of theHP11. The hotspot on high bleeds to just about the hp11 size. I will do some outside shots later, if other don't.>






*Here, bolstering the argument for the xpg, is a comparison to a $8.99 brick & mortar flashlight (price probably not reason for xp-e), using an xpg of unknown bin:
https://docs.google.com/file/d/0ByvnKHNhvrTmMV9VUFUzQm9WVEU/edit?usp=sharing


The xpg is the cool spot on left with tighter, brighter corona, which over powers the hp25 corona. You cannot tell from picture that the candela is 9500 at this drive level, which is more than the hp25. I verified with a thoroughly diffused lux ratio, the claimed 12% more lumens. The color of the HP25 is warmer, with a hint of green--but beside this cool xpg, the color is better. I prefer the hp11 color (range, as I own 5 units) best, personally.

<The xpe drive level is tailcap .53 over 4 cells, and the xpg .53 amp from 3 cells. Even with %25 less wattage, the overall output of the xpg is %12 higher and the lux is %50 greater. I suspect, the xpg bin is an r4 (I am reading130 lumen, at least, for 350 ma:) https://docs.google.com/file/d/0ByvnKHNhvrTmcnBhQXJEZ0FIZW8/edit?usp=sharing.
>

Here's an end-of-life discharge graph with 3 and 4 cells, in both cases starting just after the light dropped out of regulation, running 180lm setting on the flood beam.
To try and get some vague standardisation as well as keeping test times down, cells were discharged on a C9000 and then given a short recharge before using.

In the case of the 4-cell discharge, by the time the test was terminated, the weakest cell out of the 4 was experiencing meaningful voltage reversal, which underlines that it's probably not great for cell life if 4xNiMH cells are run to the point where the output is seriously diminished

degarb,
If there are differences in the flood beam's overall output per watt compared to other lights, that might be at least partly down to the optical arrangement.

In the HP25

there seems to be a small plastic optic used for the flood LED, but it appears to be mounted rather like a lens would be - some way in front of the LED, allowing some of the more-off-axis to bounce around inside the light.
That could potentially account for some differences in overall power output compared to a light with a more efficient system, even if the HP25 arrangement may have been chosen to give some particular beam characteristics.

Since the reflector ring on the HP25 flood beam seems to be simply cosmetic*, I'm intrigued as to why the optic actually used to shape the beam seems to be so small.
Though since such design decisions are unlikely to be explained in public, I suspect I will stay intrigued.

(*It's hard to be sure, but there doesn't seem to be any angle at which the flood LED's yellow die can be seen reflected in the reflector, which suggest it is unlikely to play a meaningful part in the beam.)

uk_caver said:

degarb,

There seems to be a small plastic optic used for the flood LED, but it appears to be mounted rather like a
lens would be - some way in front of the LED, allowing some of the more-off-axis to bounce around inside the light.

That could potentially account for some differences in overall power output compared to a light with a more efficient system, even if the HP25 arrangement may have been chosen to give some particular beam characteristics.

Click to expand...

I didn't get to the outdoor beam shots yet. Looks like my bt20 shipped, so the new light may motivate me.

I have visually compared the Hp25 flood to my Defiant xp-g r3 headlamp (Home Depot, I think). <The Defiant light has a lens and reflector that simply pops out if you pull on it, making it a perfect flood--my preferred strategy for going from flood to throw.> The defiant light draws a comparable current to the hp25 on the 90 lumen setting-typically 220 ma from three cells-, where I estimate (with diffused lux ratio to known hp11 light) at 90 lumens. Subjectively, both outputs were equal in lux and overall. There is a handicap, however; the HP25 must go through loss of the lens optic. I didn't get around to testing the two's 90 lumen lux number with a meter.

I finished the runtime test off 6volt ub645 agm. This test (three segments), it ran in regulation 9h30 minutes on high spot. Do cavers wear back packs? I always work wearing a tool belt, but probably would dedicate a fanny pack to the battery.

4 18650s is so lightweight as to be unnoticed on my belt loop. Just more hassle and costly. I am still studying if this light is worth (due to xpe droop) a four 18650 pack for my purposes, where, even then, 6.5 hours would be the expected best runtime when run all high. http://dx.com/s/18650.html?category=400&gclid=CM73u5aY7rcCFZFcMgodgQsA4w&sort=-Price

degarb said:

I finished the runtime test off 6volt ub645 agm. This test (three segments), it ran in regulation 9h30 minutes on high spot. Do cavers wear back packs?

Click to expand...

Very few seem to like using other than helmet-mounted batteries.

HP25 beam shots. Here are some outdoor photos for your review of the hp25, compared with other similar lights (output and drive). The little tree is 75 feet out and far grass line is 100 feet. A few pics came out blurry, but I am out of repellant, and they are biting hard. (I am a quart low on blood just from this round.) Sad, really, since some of my favorites are blurry. However, the luminous essence translates even in the blurry photos. Pretty much what I was seeing.

Google Drive Public Link to full comparitive beamshots folder: https://drive.google.com/folderview?id=0ByvnKHNhvrTmYm1IOHNfUEttYmM&usp=sharing


All lights here are Fenix, specs at fenixtactical.com or your favorite fenix store-- except the Utilitech light (a $9 xpg brick&mortar comparison, of mid 2013).

HP25 340 Lumens 1.05 amps

Hp25 180 spot (.53 amp)



HP11, 277 lumens, with dirty/dusty optical lens, I believe. (circa %67 of amps of hp25 180 spot+180 flood, yet greater throw, spill, output than the hp25's spot high+flood high. See how tree is lit up, where dark in even the 360 lumen hp25. ):


$9 Utilitech, rated 200 lumens, at .53 amp:


The Utilitech is $8.99 direct drive flashlight (3AAA, plastic lens, smooth reflector) from Lowes. XP-g, I am getting reading of 225 lumen range at .53 amp, around 300 lumens direct drive from 18650 (easy mod, with aluminum foil and rubber bands. She runs for about 3 hours flat out with my 2600's) sucking down .8 amp, and 133 lumens at .36 amp old cells (a tad tighter and throwier than the hp11.)

TK35 - 360 lumens - 7.5 hours off two 18650 (My favorite, but sadly blurry; taken during a mosquito attack. The next shot on the camera was all blood.)



BT 20 - 6.5 hours - 300 lumens:

BT 20 - 450 lumens - 8 hours off 4 18650:



I think the BT20 actually has a far better flood/spot beam pattern than the hp25. But it is hardly a fair fight, since we are talking better emitter and better battery source. Fenix does need to work on the form factor of the TK35 and Bt20, as they are a bit unnecessarily bulky--which makes the making of a headlamp and wristlight awkward, out of the Bt20 and Tk35, respectively. (I just got my BT20. But I would like anyone to pm me if they have a solution to wear it on the head without a helmet.)

Now, the juice guzzling, shots:

Bt20 - 750:
Uploaded with ImageShack.com

Tk35 850



My camera doesn't translate lux all that well. Though, I think very representative of the lux, in these photos. As I recall, bt20 300 (~2300 candela, too low for 6 foot wall inspection) bt20 450 lumens (4000 candela, ahh just fine for 3-6 foot wall inspection, but full day will eat four 18650s), Tk35 360 (something like 9000 candela, not bad for two 18650s per day) Utilitech 9-12000 candela with 3 AAA or 1 18650. The max of the hp25 candela is under 6000, while the hp11 is 7800. The hp25 candela on 90 lumen spot is somewhere, I recall in the 3000 range, with is too low for for 6 foot, okay at arm length--(I trust only 1000 candela or greater for 1 meter wall inspection, and 4000 for 2 meter, and 9000 candela for 3 meter.)

If they chose xp-e for flood for economic reasons, why not xt-e (closer to an xml for efficiency)? I would assume after 2 years, the xt-e color issue has improved.

Naturally, my preference would be to stick an xte (with driver) onto the side of the well designed hp11 (bump her up to an xpg2). Charge an extra $20, and call it a day.

Have you used it in a wet cave yet? I took mine caving in a semi-dry cave and it did well, but I noticed it is rated IPX 6.

So no immersion, correct?