Need a scientific laboratory flashlight

[Xe54]

Hi:

I'm a laser/optical/electronics technologist in a research department with 8 laboratories, studying optically accessible internal combustion engines. Most of the labs have 2D Mag lights. I'm considering to persuade them to switch to single 18650 powered lights, so we don't have to deal with the battery waste (CA), and also for the superior inspection/task lighting characteristics of a nearly gaussian LED flashlight beam profile.

So the question is, which flashlights can satisfy the following criteria:

1. can take 1 x 18650 (UPDATE: 2 x AA is the only format now under consideration, due to Li-ion safety concerns.)

2. have 2-3 levels easily accessed by either a tail switch or a ring adjust. IF the tail switch sets levels, then it must memorize the level. A good medium of 50-100 lm would be nice, as well as a high of 150-200 lm. These numbers are flexible. Forward or rev. clicky isn't critical. But it must turn on and off with one switch cycle. I don't like lights that have to click through two levels to get turned off.

3. are not physically too small--too small will be hard to find among clutter. A typical 2xCR123 tactical flashlight size is probably the minimum size that is acceptable. Larger is OK too. Must stand on the bezel easily, so a bezel of larger diameter than the body is preferred.

4. has a smooth beam profile even fairly close, such as at 6 inches from the bezel. This concern arises from the fact that large reflector lights can have a donut profile up close, and take some distance before the beam fills in. But since this light will be used primarily for illuminating optics and other things at distances of 6-18 inches, the beam must be smooth as close to the light's business end as possible.

5. can be purchased for a budgetary range of $75-100. I know this would be much easier if I could go up to the $150 range, but I'd prefer to stay below $100. If there are supremely ideal lights that anyone can speak of which perfectly satisfy the other criteria, then feel free to mention them. For instance, I am interested in the Jetbeam Raptor series, but I'm not sure about their up-close beam profiles. They are in the <$150 price range though.

6. available through distributors that take VISA. No paypal. Prefer something manufactured by a regular volume maker that's been in business for a few years, rather than something custom/one-off.

Thanks for any feedback.

[tino_ale]

I'm gonna let others to suggest the best pick, but...

This only reminds me how some "high technology" professionnals are still using very mediocre lights at work eventhough it is sometime a tool of first importance. Good thing that you are willing to adress this.

[Xe54]

Just to clarify:

1. can take 1 x 18650

That is one 18650 lithium ion cell. This is highly preferrable to a 2xCR123 light with a 17670 (presuming it can work with lower voltage), simply because changing cells is an inconvenience, so minimizing the frequency of battery swapping is important.

The door is also open for flashlights which are rechargeable without removing the cells, I suppose.

[RobertM]

How about a Zebralight H60W? Aside from it being kinda small, I think it would fit most of your requirements.

-Robert

[Moonshadow]

A good medium of 50-100 lm would be nice, as well as a high of 150-200 lm . . .

. . . this light will be used primarily for illuminating optics and other things at distances of 6-18 inches . . .

Jeepers ! 150 - 200 lumens at 6 - 18 inches . . . are you sure ???

[ZMZ67]

No experience with 18650 lights so I don't have a recommendation but I am wondering if tint matters? The majority of LED lights will have a cool tints much different than the warm output from a 2D Mag w/stock bulb.
Usually cool tinted lights are fine for indoor use but for color rendition warmer tints may be better.

[lxhunter]

You came to the right place for advice - you will get lots of good specific suggestions. And you have described your needs very thoroughly.

I can only comment on a few general suggestions:

Beam - you may consider adding a "beam shaper" a white translucent filter which is helpful for close up work. Most major companies sell one, or there are many aftermarket providers. Along with a variable output with a low setting.

Hazardous environment - you work in a lab, so you don't need any lecture from me - but you may wish to review this link - and its not an endorsement of a specific manufacturer - just a source of info
http://www.streamlight.com/education/safety-ratings.aspx

Body Colour - you may consider a brightly coloured light - for example a Surefire G2L in yellow - less likey to misplace. This is just an example of a brightly coloured light and does not meet the criteria you describe.

Ergonomics - you have considered a twist or clicky control. And, I believe you can find that all major manufactures and aftermarket lens/light manufacturers offer lamp assemblies which retain the last light setting.

[Nightstalker1993]

hmm. first thing that came to mind was the ET T100c2. though it is a thrower, its pretty big and since its using an xp-e LED, the beam is flawless. runtimes on 18650s are practically flat all the way.

loosen head for low 55l, tighten head for high 220l

[Xe54]

No experience with 18650 lights so I don't have a recommendation but I am wondering if tint matters? The majority of LED lights will have a cool tints much different than the warm output from a 2D Mag w/stock bulb.
Usually cool tinted lights are fine for indoor use but for color rendition warmer tints may be better.

I might go for a warm, if it's available in the model of light that satisfies all the other criteria. But color is flexible. Beam profile is more important than color for this application.

[Xe54]

hmm. first thing that came to mind was the ET T100c2. though it is a thrower, its pretty big and since its using an xp-e LED, the beam is flawless. runtimes on 18650s are practically flat all the way.

loosen head for low 55l, tighten head for high 220l

Thanks for the suggestion.

XP-E is nice. I just bought a couple Quarks with this.

One thing I am opposed to though is overdrive. As an electronics designer, this is completely forbidden with power semiconductors such as MOSFETs, ordinary diodes and transistors. I think it is courting disaster with LEDs. I have written about this several times in the past here on CPF.

I suspect the EagleTac is overdriving, since from the datasheet graph an R2 XP-E at 70mA is about 175% over the base spec of 114 lm/350mA, which translates to 199 lm, but EagleTac is advertising 220 lm.

If I want a light to be reliable for 5-10 years, I don't want it to be overdriven.

[RocketTomato]

How about a Jet-III M? It does not have 2-3 levels but instead has the infinitely variable brightness system (I.B.S.) that Jetbeam uses.

[Bullzeyebill]

Thanks for the suggestion.

XP-E is nice. I just bought a couple Quarks with this.

One thing I am opposed to though is overdrive. As an electronics designer, this is completely forbidden with power semiconductors such as MOSFETs, ordinary diodes and transistors. I think it is courting disaster with LEDs. I have written about this several times in the past here on CPF.

I suspect the EagleTac is overdriving, since from the datasheet graph an R2 XP-E at 70mA is about 175% over the base spec of 114 lm/350mA, which translates to 199 lm, but EagleTac is advertising 220 lm.

If I want a light to be reliable for 5-10 years, I don't want it to be overdriven.

How far over 700mA's do you think that EagleTac is overdriving the LED? You did mean 700mA, instead of 70?

Bill

[lolzertank]

Solarforce L2 18650 with a R2 dropin isn't too expensive at about $40 for the whole set including a battery and charger.

[Xe54]

How far over 700mA's do you think that EagleTac is overdriving the LED? You did mean 700mA, instead of 70?
Bill

Eyeball extrapolating from the chart, I'd say 800 to 900 mA (probably closer to 800 mA). Their stated 220 lm is 1.93 times the base 114 lm. The chart cuts off at 700mA, so its a rough guess. But at 700mA, the XP-E puts out 175% of base, which is 1.75*114 lm for an R2, = 200 lm. Anything over 200 lm is overdriven.

Ugh, this isn't helping to keep the thread focussed on the original question.

[Zeruel]

How about a Zebralight H60W? Aside from it being kinda small, I think it would fit most of your requirements.

-Robert

This is the first light that came to mind too. In a lab, you don't really need a thrower, do you?

[Xe54]

Solarforce L2 18650 with a R2 dropin isn't too expensive at about $40 for the whole set including a battery and charger.

That is very inexpensive, which could be very helpful in convincing the whole group of 8 scientists to buy these things. I wouldn't mind a standardized system.

What is most interesting about these Solarforce lights is that they have incandescents available as well.

Solarforce mentions that a new IH-1 (Xenon bulb module) for a single 18650 cell is available. I wonder, is this a regulated xenon driver? If so, that would be extremely sweet, for applications needing the 100 CRI of a real lightbulb.

Do any other brands offer xenon/LED exchangeability?

[StarHalo]

You might consider a 1xAA format light - using a rechargeable NiMH cell, there's no way to overdrive one of these, so you can safely leave the light on at any output level. The NiMH battery is much safer during recharging, does not require constant multimeter checking to prevent overdischarge, and is much cheaper and easier to come by (plus in the event of an emergency, any AA-sized cell from any other battery-powered item in the area can power the light, not an option with 18650.)

A 1xAA light is smaller than an 18650 model, and you're looking at a max output of 130-140 lumens, but there's a broad range of models and features to choose from, and they very rarely go near the upper end of your price scale.

[Xe54]

This is the first light that came to mind too. In a lab, you don't really need a thrower, do you?

Not a thrower, but neither a flood. A nice gaussian is best. There are times we want to shine the light through an optical window 6-12 inches from the light, with about 1-2 sq. in. clear aperture area, onto a target region 0-6 in. behind the window. So an oversized head/beam won't help there. Other times, direct lighting of various stuff over a range of indoor, living-room distances. Other times through a 2-3 ft. path bouncing up a mirror with about 2-3" clear aperture, into a chamber.

[Xe54]

You might consider a 1xAA format light - using a rechargeable NiMH cell, there's no way to overdrive one of these, so you can safely leave the light on at any output level. The NiMH battery is much safer during recharging, does not require constant multimeter checking to prevent overdischarge, and is much cheaper and easier to come by (plus in the event of an emergency, any AA-sized cell from any other battery-powered item in the area can power the light, not an option with 18650.)

A 1xAA light is smaller than an 18650 model, and you're looking at a max output of 130-140 lumens, but there's a broad range of models and features to choose from, and they very rarely go near the upper end of your price scale.

I have considered this quite carefully. A single cell has the advantage of no balancing issues, which is why I prefer to stay there. All of my experience with the use of more than a single NiMH has been plagued by trouble due to cell voltage reversal when one peters out and the other is still pushing current. If I did go with NiMH, it might be better to have 2 cells for greater capacity, and a bit larger size to the light. Single AA lights are a bit too small.

That's why I like 18650. In single cell, it has the most capacity. As well as fitting generally larger lights than the typical slender AA formats. A light with a head wider than the body stands easily. We usually stand our lights on the head so they stick up and are easy to find/grab.

Is the over-discharge issue truly significant with protected Li-ion cells? My sense is that with a charger that is sure to cut off when fully charged, and a protected cell, that the hazard of using protected bare cells is no greater than what we accept with proprietary Li-ion packs such as in our cell phones, etc.

[StarHalo]

Is the over-discharge issue truly significant with protected Li-ion cells?

Very much so, since they usually won't cut off until 3 volts; a Li-Ion cell starts getting damaged below 3.6 volts, and the longer you leave it below that voltage, the more damage is done. Plus not all chargers cut off at the proper voltage, many continue to trickle charge as long as they're on, which is pretty much guaranteed to cause an explosion over a long enough period of time.

I understand your size concerns, but "laboratory" and "Li-Ion" don't really go together in my mind.

[LightScene]

The Jetbeam Jet III M (Military) uses one 18650. It is good sized. It has 2 levels - 1) full - head tight, 2) your choice - head loosened. The rear clicky switch is 'tactical', meaning it turns on as soon as you press it and stays on if you click it. For your purposes, the Warm version with OP reflector should be perfect. I just tried it at my desk and the full brightness is not startling to the eyes. This flashlight costs about $85 and is built very strong. The bezel is flat stainless, perfect for standing on. The tailcap is also stainless. The front lens is shock protected. At a distance of 6", the hot-spot has a diameter of 1". There is no dark spot in the middle at any distance.

When you asked about over-discharge, I think you meant over-charge. As a precaution, you could put the charger on a timer, just in case it malfunctions. I don't worry about it myself, but some people in this forum are very paranoid on this issue. You could also create a charging station that is fire proof - like the inside of metal trash can, etc.

[MattK]

Olight M20 or Fenix TK11 should both suit your needs.

Alternatively the Maglites could be converted to LED with TerraLUX TLE-6EXB's and you could power them with NiMh D cells.

[Xe54]

Very much so, since they usually won't cut off until 3 volts; a Li-Ion cell starts getting damaged below 3.6 volts, and the longer you leave it below that voltage, the more damage is done. Plus not all chargers cut off at the proper voltage, many continue to trickle charge as long as they're on, which is pretty much guaranteed to cause an explosion over a long enough period of time.

I understand your size concerns, but "laboratory" and "Li-Ion" don't really go together in my mind.

Oh good grief, now you have me 2nd guessing the Li-ion idea!

Nonetheless, I'm skeptical of the statement that Li-ion gets "damaged" below 3.6V. Can you provide some references for this?

I know that the risk of the cell being killed by excessive discharge occurs in the 2.5-2.7V range. There is also the fact that permanent loss of capacity over time has a rate which is SOC dependent. At 40% SOC, the rate seems to be minimized. Above about 50-60%, the rate increases significantly. And presumably, below 40%, it may increase as well. But that doesn't mean we avoid fully charging our batteries. It depends where our priorities lie.

In terms of safety, the main danger seems to be overcharge, rather than undercharge. Overcharged Li-ion is likely to explode. Undercharged cells might lock themselves out.

It all depends on the protective circuit. Should we ban cell phones, digital cameras, and Li-ion powered portable power tools in our labs just because unprotected Li-ions have significant risks of explosion? Why should we trust proprietary protected packs any more/less than individual cells with protection PCBs?

I do work in a place that is extremely concerned about safety, it should be stated. So perhaps I will think about this for another iteration.

The Fenix TK20 is now becoming an interesting option. I didn't realize until now that there are some nice 2xAA bodies that are not just the cylinder format.

I suppose the modest degradation of NiMH longevity that results from brief cell voltage reversal is not too high a price to pay for the peace of mind of not having to worry about Li-ion cells. The TK20 has a nice balance of outputs between its two modes.

[Rexlion]

That's funny. I was reading this thread and thinking that I'd suggest the TK20... then I get to the last post and there, you are already considering it. Warm emitter, choice of gray or yellow grip, 2 modes. I have one and it feels very sturdy and reassuring in the hand. I think you could run over it with a bulldozer and it would still work (admittedly I have no empirical data).

The other one that came to mind was the Nitecore D20. Whatever light level you set it to is the level that comes on the next time it's turned on.

After reading here a while about Li-Ion potential dangers and limitations, it does not seem like the sort of thing I would picture in a safety-oriented lab. Especially if you don't know who is going to be charging and reloading these cells... too many cooks spoil the broth, as they say. It would only take one time of someone putting a Li-Ion in a charger backward, and they would be asking who was the turkey who organized the purchase of those little bomblets.

[recDNA]

Oh good grief, now you have me 2nd guessing the Li-ion idea!

Nonetheless, I'm skeptical of the statement that Li-ion gets "damaged" below 3.6V. Can you provide some references for this?

I know that the risk of the cell being killed by excessive discharge occurs in the 2.5-2.7V range. There is also the fact that permanent loss of capacity over time has a rate which is SOC dependent. At 40% SOC, the rate seems to be minimized. Above about 50-60%, the rate increases significantly. And presumably, below 40%, it may increase as well. But that doesn't mean we avoid fully charging our batteries. It depends where our priorities lie.

In terms of safety, the main danger seems to be overcharge, rather than undercharge. Overcharged Li-ion is likely to explode. Undercharged cells might lock themselves out.

It all depends on the protective circuit. Should we ban cell phones, digital cameras, and Li-ion powered portable power tools in our labs just because unprotected Li-ions have significant risks of explosion? Why should we trust proprietary protected packs any more/less than individual cells with protection PCBs?

I do work in a place that is extremely concerned about safety, it should be stated. So perhaps I will think about this for another iteration.

The Fenix TK20 is now becoming an interesting option. I didn't realize until now that there are some nice 2xAA bodies that are not just the cylinder format.

I suppose the modest degradation of NiMH longevity that results from brief cell voltage reversal is not too high a price to pay for the peace of mind of not having to worry about Li-ion cells. The TK20 has a nice balance of outputs between its two modes.

The 2 X AA NiMH form seems safer and still meets all of the other criteria. The Quark 2 X AA would seem a decent choice.

[StarHalo]

Nonetheless, I'm skeptical of the statement that Li-ion gets "damaged" below 3.6V. Can you provide some references for this?

From our resident battery expert moderator:

The 3.6 volt figure is open circuit voltage taken several minutes after the load has been removed.

This 3.6 volt value came from the RC people. The did a series of tests by setting the low voltage cut off devices they use to different levels. They are typically drawing high currents. Since each airplane and RC vehicle is set up a little differently, they set upon open circuit resting voltage as an indicator of over discharge.

This means that a cell could be run at a 2C current down to 2.5 volts, and if the voltage rebounds to 3.6 volts after a few minutes of resting, unloaded, it probably hasn't been over discharged to the point of damaging cycle life. On the other hand, the same cell discharged at a 0.1C rate down to 2.5 volts may only rebound to 2.7 volts after resting, and it has probably been damaged.

Also, keep in mind that in normal electronic use the protection circuit is a back up termination method. The devices circuit will usually signal low battery and shut down before the protection circuit cuts in. This means that the protection circuit is designed to avoid major damage to the cell, and not that it is good to use that voltage as a normal discharge cut off.

Li-Ion cells seem to be a little different. They seem to be easily damaged at higher or lower than "normal" voltages. The damage is compounded by the amount of time spent outside the normal range, but over voltage incurs almost immediate damage, and under voltage, while it takes a little longer to occur, does end up damaging the cell.

From Cy's "Li-Ion Greatest Danger" thread:

it's extremely hard to cause a NMH battery to explode. VS it's relatively easy to cause a li-ion cell to explode by overcharging.

I'm not one of those "be afraid" folk; I EDC a 14500-powered light daily, but I'm pretty sure there are some laboratories and other various sensitive areas where it would not be welcome..

Also -

It all depends on the protective circuit. Should we ban cell phones, digital cameras, and Li-ion powered portable power tools in our labs just because unprotected Li-ions have significant risks of explosion? Why should we trust proprietary protected packs any more/less than individual cells with protection PCBs?

The protection on those devices uses an active circuit to check the status of the battery so that it always remains within its safe operating range. The PCB that's built into protected Li-Ion cells is just there to ensure the battery doesn't overheat and doesn't drain so low that the cell would die completely, nothing more. It does not protect against overcharge, slow over-discharge, etc. Li-Ion manufacturers assume you're using their cells in something that monitors their status, which flashlights do not.

[Mjolnir]

Starhalo, you have shown that anything below 3.6 with an open circuit can damage the cell, but I'm not sure that your statement about protection circuits is entirely accurate, or at least you haven't really shown proof of it. It could be that a "depleted" Lithium ion cell that has just has its protection circuit tripped would read 3.0 volts without any load, but I think that that is lower than what most protection circuits do. They may be more like 2.7 volts with a load, which might be above 3.0 V without load. I don't regularly deplete my 18650s until the circuit is tripped, so I am not really sure what circuits actually cut off at.

Another option would be to get a light like the L-mini II, which automatically switches to low mode when the battery gets low (either 3.2 V or 3 V under load; I don't remember the exact number).

[StarHalo]

It could be that a "depleted" Lithium ion cell that has just has its protection circuit tripped would read 3.0 volts without any load

After the load is removed, the cell will begin to rebound - the problem is how much it rebounds is determined by the drain rate; if you were driving the cell hard, it will rebound a lot, no harm done. But if you drained it lightly over a long period of time, it will barely rebound at all and now (at lower voltages) you've damaged the cell. Therefore there needs to be a "safe zone" voltage that lets you know when to recharge regardless of drain rate; this has been established as 3.6 volts.

Another option would be to get a light like the L-mini II, which automatically switches to low mode when the battery gets low (either 3.2 V or 3 V under load; I don't remember the exact number).

This would make the problem worse, as now you're shifting to a light drain right as the cell's PCB is starting to trip, making it very easy to overdischarge the cell - on the plus side, this is at least a low battery indicator.

[RocketTomato]

Use protected batteries and get a Pila IBC Li-ion charger. If you want to be extra safe, then put the Pila on a wall timer so it cuts the power after 5 hours. Also, a Solarforce L2 with an R2 drop-in is a single level light I believe.

[Xe54]

Ok, the official word on this topic is that I will switch to considering 2 x AA lights. Li-ion is out. I'll be sticking with Li-ion for my personal lights, but I agree that it's not preferrable for the lab. One of the scientists I've queried agrees as well, after explaining the issues with Li-ion.

I've compiled a list of possible 2 x AA lights, including some initial comments about their viability or any rule-outs:

Fenix LD20
Fenix TK20 (neutral/warm white only)
Fenix E20 -- very interesting focus feature may outweigh single mode
Quark AA^2 tactical R2
Quark AA^2 regular R2
Quark AA^2 tactical neutral/warm white (ltd. run)
Quark AA^2 regular neutral/warm white (ltd. run)
Olight T25 regular
Olight T25 tactical
Nitecore D20 -- I'm ruling out due to concerns over stickiness of plunger
Jet-I Pro EX v.2 -- ruled out due to too wide gap between low/high modes
EagleTac P100A2 -- ruling out due to superior bezel ruggedness and slightly smoother beam of P10A2
EagleTac P10A2

I'm definitely inclining toward tactical forward clicky here. I also am inclining toward simpler UIs, which don't require stepping through modes to get the desired light. For this reason, I may rule out LD20 and the non-tactical FW clicky versions of the other brands.

The round-up review of 2xAAs has impressed me with the beam quality of the EagleTacs. These are also very reasonably priced. I hope they will last a long time if I choose to buy them. They are also simple to operate with just two levels, and the spacing between the levels is a good balance.

I had been seriously considering the TK20, just because the enlarged head and yellow body has benefits for ease of setting down and finding. But, I'm a bit put off by pictures I've seen of the beam profile.

Undecided about warm whites. I have recently bought one for home (a Quark, mainly for it's moonlight mode), and will be lending it to a scientist (guinea pig) in the next few days. BTW, the same scientist (actually a post-doc) is now hooked on an old Luma hunter that I gave him to try out the general characteristics of LED lights. He and the main scientist in that lab are mainly falling in love with the smooth beam.

Thanks for feedback folks.