Need a scientific laboratory flashlight

[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). :laughing:

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.

 

[Xe54]

Jet-I Pro EX v.2 -- ruled out due to too wide gap between low/high modes

Oh, I realize now that this light is continuously variable. It's back in the running!

 

[Mjolnir]

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.

Although I didn't mention it, the L-mini II also has a protection circuit built in, so it cuts off at a certain point even if the batteries do not. The low mode tells you that it is time to switch/recharge the batteries, but if you really need the light it will still function, although it may harm the batteries.

Either way, 18650s are so cheap these days that it isn't all that big of an issue to shorten the lifespan on one.

 

[StarHalo]

I'm definitely inclining toward tactical forward clicky here.

In your first post, you noted that you wanted the light to "stand on the bezel"; if you meant the rear bezel, a "tailstand", that could be a problem as most forward-clickies protrude and can't tailstand. (If you meant stand on the front bezel, then no worries, as any flashlight can do that.)

I also am inclining toward simpler UIs, which don't require stepping through modes to get the desired light.

This is an important concept in buying any flashlight that anyone else will be using; you don't want people in emergency situations fumbling with flashlights they don't understand, or leaving flashlights on a "turbo" mode, etc.

He and the main scientist in that lab are mainly falling in love with the smooth beam.

Your need for a smooth beam and simplicity leads me to believe the Fenix E20 might be your winner; a single mode with a simple forward on-off switch, no modes or overly technical features. And one very big feature of focus-head lights that most people overlook is the ability to remove the head entirely and use the light bare-emitter - this is the smoothest possible beam an LED is capable of since it just radiates light openly in a ~180 degree spread. You can hold this type of light just a few inches away from a page and it will fill the entire page with smooth and even light, no transition in the beam type or artifacts, just garage worklight-type ambient light.

 

[recDNA]

In your first post, you noted that you wanted the light to "stand on the bezel"; if you meant the rear bezel, a "tailstand", that could be a problem as most forward-clickies protrude and can't tailstand. (If you meant stand on the front bezel, then no worries, as any flashlight can do that.)



This is an important concept in buying any flashlight that anyone else will be using; you don't want people in emergency situations fumbling with flashlights they don't understand, or leaving flashlights on a "turbo" mode, etc.



Your need for a smooth beam and simplicity leads me to believe the Fenix E20 might be your winner; a single mode with a simple forward on-off switch, no modes or overly technical features. And one very big feature of focus-head lights that most people overlook is the ability to remove the head entirely and use the light bare-emitter - this is the smoothest possible beam an LED is capable of since it just radiates light openly in a ~180 degree spread. You can hold this type of light just a few inches away from a page and it will fill the entire page with smooth and even light, no transition in the beam type or artifacts, just garage worklight-type ambient light.

Won't the led burn out w/o the head as a heat sink?

 

[StarHalo]

Won't the led burn out w/o the head as a heat sink?

It sinks to the rear, not to the front. I have a JetBeam I've used for many months in this fashion with no issues.

 

[ZMZ67]

I think the 2AA is definately the best way to go.Was surprised to see you were considering the TK20 as it is designed to throw a fair distance.I would be cautious in choosing lights using the the CREE XR-E as they often have rings in the beam.Pretty sure they will be evident on the TK20 as it uses a smooth reflector IIRC.Didnt want to recommend anything before but since you are considering AA lights the 2AA Quark tactical seems like the best choice to me.I like the regular model but if you want the forward clicky and simpler UI the tactical is probably the way to go.If you go with the Quarks you can choose either cool or warm tint or even get several of each if you find both tints offer value.

 

[Xe54]

In your first post, you noted that you wanted the light to "stand on the bezel"; if you meant the rear bezel, a "tailstand", that could be a problem as most forward-clickies protrude and can't tailstand. (If you meant stand on the front bezel, then no worries, as any flashlight can do that.)

I meant the front bezel. The reason being simply that we usually put our Mag Lights down on the head. They stick up far above the optical table surface among the other items, so are easy to grab.

Your need for a smooth beam and simplicity leads me to believe the Fenix E20 might be your winner; a single mode with a simple forward on-off switch, no modes or overly technical features. And one very big feature of focus-head lights that most people overlook is the ability to remove the head entirely and use the light bare-emitter - this is the smoothest possible beam an LED is capable of since it just radiates light openly in a ~180 degree spread. You can hold this type of light just a few inches away from a page and it will fill the entire page with smooth and even light, no transition in the beam type or artifacts, just garage worklight-type ambient light.

I still use a MiniMag for this purpose. I have discovered that on 2xAA NiMH cells, the lower voltage makes the light bulb not blacken quickly, as it does with regular cells, or even worse with Li. Also, the flat discharge curve of NiMH makes it light relatively constantly for a good while. I use this setup with the head removed for inspecting laser optics. It is essential to be able to view reflected light off the optic at various angles to see flaws.

I'm actually getting tempted to put a tiny SMD LED on the end of a pair of wires, so the light source can fit into smaller spaces.

It will be interesting to see how the E20 performs. I may buy one just to evaluate. For general use though, I still think at least a two-level light might be preferrable. Ring adjust lights are interesting here since you can see the level setting (assuming it has a pointer and decals, unlike SF U2, unfortunately).

 

[Xe54]

I think the 2AA is definately the best way to go.Was surprised to see you were considering the TK20 as it is designed to throw a fair distance.I would be cautious in choosing lights using the the CREE XR-E as they often have rings in the beam.Pretty sure they will be evident on the TK20 as it uses a smooth reflector IIRC.Didnt want to recommend anything before but since you are considering AA lights the 2AA Quark tactical seems like the best choice to me.I like the regular model but if you want the forward clicky and simpler UI the tactical is probably the way to go.If you go with the Quarks you can choose either cool or warm tint or even get several of each if you find both tints offer value.

The Cree rings are usually subtle enough to not bother me. Only the photos of the TK20 that I've seen show rings worst than many other lights. Then again, photos can be deceptive.

Aside from the throw-iness of the TK20, which may be unsuitable for the task, I am also not sure about the warm whites. I have a Quark AA neutral at home, which I thought was really neat until I got a Dereelight pill with a Q3 5A. The pill makes a light that is gorgeous! It's creamy white, just a bit cooler than some 3500K Sylvania CF lamps that I use. The Quark OTOH, is was too yellow for my tastes, after comparing to this. However, when it is very dark, the Quark light is quite pleasant.

Perhaps the Luxeon lottery involves even more variance with current warms than with cools.

The tactical quark is a contender because I can program it to medium and high, then forget it. I can train the Ph.D's to know that the bezel turns, then it should be simple enough for them to handle.

However, the efficiency of Quark isn't that great. Fenix really seems to have their act together here, though I realize that it has to do with PWM vs. current regulation.

 

[selfbuilt]

It will be interesting to see how the E20 performs. I may buy one just to evaluate. For general use though, I still think at least a two-level light might be preferrable.

+1 for that. I think you would find the E20 way too bright for the kind of up-close work you've described. A multi-mode light sounds like a must to me.

Aside from the throw-iness of the TK20, which may be unsuitable for the task, I am also not sure about the warm whites. I have a Quark AA neutral at home, which I thought was really neat until I got a Dereelight pill with a Q3 5A.

Actually, I believe the TK20 is using a Q3 5A as well. But I agree that this light is probably way too throwy for your needs. Ideally, I would recommend you get something with an even lower low.

I also think something that a good diffuser would be a good idea - for really close-up work, it will definitely help. I notice 4sevens is selling a diffuser cover for the new Fenix headlamp that will fit standard Fenix LDx0/PDx0 heads. There's also the Olight T-series filters ....

However, the efficiency of Quark isn't that great. Fenix really seems to have their act together here, though I realize that it has to do with PWM vs. current regulation.

:thinking: The Quark's use basically the same circuits as their Fenix counterparts, with an added ultra-low mode and full support on Li-ion. It would be tough to top their efficiency. See my Quark round-up thread for runtimes. The variation seems fairly minimal (and likely due to Vf difference between sample emitters).

FYI, as an aside, I would suggest you consider sticking with something relatively inexpensive. I think you will find whatever you buy with walk out of the labs pretty fast ... once people see how much better they are than standard mags or cheapies LEDs.

 

[ZMZ67]

Still feel the 2AA Quark tactical will fill your needs but selfbuilt makes a good point at the end of his post.It is quite possible the lights will end up missing from the lab.