SF G2L + informal runtime graph

I got my SureFire G2L about a month ago and have since been using it for everyday lighting tasks. My L1 CREE is on my person far more often, due to size and the pocket clip (which I clip to my belt), but the G2L nevertheless makes it into my pocket, as its size really isn't unreasonable.

Body

(And yes, you can disregard this section if you're familiar with the G2). This is probably stating the well-known, but the G2L feels good in the hand, being the perfect size to hold and handle. The Nitrolon material has a great feel to it, and is definitely more more pleasant than its peers in situations where metal lights would be scorching hot (like for sitting in the sun) or painfully cold. The grid and matte texture seem like they'd be good in slippery conditions, though the "SureFire" text can be a little rough on the hand, depending on how it's being held (though probably no more so than aggressive forms of knurling). The only significant downside I can find to the body is the lack of the six-sided anti-roll section on the head. Other than that, this light is ergonomically stellar.

Tailcap

Took me a short while to get used to the switching mechanism (I've traditionally only used a Mag 3D, or occasionally 2AA). But the LOTC twisty has definitely grown on me, and I probably like it nearly as much as the Mag clickies I'm used to. In any case, I ordered a Z59 clicky tailcap to go along with this, and I know there are other threads that discuss this more thoroughly, but I did indeed get a defective one. It stopped clicking reliably within about 50 clicks after first use. E-mailed SureFire and they said they'd send a new one, so I'm just waiting on that.

P60L

For all my life I, like so many others, have been a faithful user of MagLites. So just this summer I decided I'd jump into some higher quality, brighter stuff, and ordered myself a G2L, G3 and L1 CREE. So coming from the Mag 3D, I was definitely impressed with the beam of the P60L. I was quite impressed with the brightness, though having read these forums for a little while now, I realize there are much brighter ones out there (confirmed by my subsequent use of the G3).

In any case, I've come to realize that the P60L is not a "bright" light. That is, brightness is not the lamp's primary purpose like it is for, say, the P91 or MN21. In my use of the P60L, I've come to the conclusion that it's just about the perfect "all-around" or "compromise" light. The brightness is significant enough that it can impress, and light up nearly anything you need it to, and simultaneously gives you fabulous runtime. I guess what I'd say for brightness comes down to the P60L being fabulously bright for close-to-medium range tasks in total dark, and is rather dim for distance lighting, or use in situations with lots of ambient light.

So I guess that brings me to throw. This is another example of the lamp's compromise. The beam has a tight, smooth hotspot with decent intensity, and a lot of bright, wide spill. In fact, if it weren't for the small hotspot, I'd almost think that this light was intended for flood use, as the spill is so bright and useful. But the hotspot comes in very handy, and can serve to highlight whatever you need it to. However, its throw isn't spectacular. I don't have a huge space I can test in right now, but from memory I'd say it is pretty useful within about 30-50 yards. For anything beyond that, I'd say that you'll want to get a light specifically designed for throw, even the relatively dim Mag 3D.

As for runtime, the P60L is very satisfactory. The "all-around" nature of the lamp, in addition to the excellent runtime would probably make the G2L, 6PL, etc., a perfect backup light for LEOs. But for the normal civilian user, I'd say that this lamp makes for a perfect emergency light. Very satisfying brightness certainly plays a part in this, but really it's the runtime that makes this light great for throwing in an emergency kit and not thinking about it until the power goes out or what have you. I'd say that SureFire's advertised 12 hours (in the G2 body) of useful light is about right. The posts here saying that the G2L starts out at 80 lumens, followed by about three hours at ~65 lumens, then drops out of regulation are about right. The 80 lumens peak really doesn't last for very long, and the following 65 lumen stage does last for a bit upwards of three hours. Well, I guess at this point I should say that my runtime test used Tenergy 3V CR123A primaries. I'm not sure how these rate compared to SF cells, or other well-known good-performers like Duracell, but at some point I'll run a test to compare the Tenergy primaries with Panasonic primaries. Anyway, on the Tenergy cells the light dropped to 50% brightness at about 4 hours, and from about 5.5 hours 'til the end of the useful light period, the G2L kept a diminishing yet stable light level that I'd estimate at an average of maybe 10 lumens. Now, 10 lumens is not a brightness that I'd want to try to use where there's a fair amount of ambient light, but in emergency situations with NO light, I think it's more than enough to get along.

Oh, and just a quick word on tint. This lamp definitely appears blue to the eye. Now, I don't have a whole lot of experience with LED lights, but I'd venture a guess that the blue of this light is a lot less distinct than LEDs of past years. I guess to be more specific, I'd say that the blue tint is definitely perceptible in about any circumstances, but after initial activation, it becomes a lot less noticeable, and all you really see is the whiteness of the beam. I say whiteness both in the sense that it's not a truly ugly blue, and also in that I was impressed at how well the lamp renders colors. Not that I have a whole lot of experience with this (or any beamshots to back me up) but I was expecting significant distortion of colors, but I really don't notice any with this lamp.

Well, I guess that's probably enough of my rambling. On to a beamshot and runtime graph. So to start out easy, here's the whitewall beamshot, taken with both the light and camera about 1 meter away from the wall; Canon Powershot A710 IS, 1/8 sec exposure, f2.8, focus set to about 1 m, ISO 80, and whitebalance set to sunlight:



I kind of feel bad for only supplying a whitewall beamshot, as I'm rather a believer in not hunting white walls, and rather just seeing how a light performs in the real world. Well, I'll try and take some pictures of both the beam and the whole flashlight and post them here at some point.

Anyway, now for the runtime graph. Okay, before you look at this thing, I want to say that this is a VERY informal graph. For starters, I have no light meter or professional light measurement technology. I was curious about the brightness of the flashlight over time, and I didn't trust my own eyes to judge that brightness, so I used another tool: my digital camera. All my data points (beamshots) were taken under the conditions listed for the above beamshot (1/8 exposure, ISO 80, etc.). I then put all the shots on my computer and used the Histograms function to compare relative brightness (I used the "mean" value that Photoshop gave me). I originally had the intention to do my graph with lumens as the y-axis units, but this proved impossible by my method, as the camera didn't capture the entire beam, and therefore it couldn't pick up all the light used for spill. I was going to use these "mean" values to compare the full brightness of the G2L with my L1 high and low beams, which I'm fairly confident are consistent with SureFire's lumens ratings. However, since the beam profiles are too different for the lights, I could only do % brightness over time. I tried to take my shots about every half hour, though I perhaps should have done more, at least for the high output period of the light. Among my possible sources for error are: distance between the tripod and wall (I had to temporarily remove the tripod from the testing room a few times), light seeping in from the crack under the door (I thought this was negligible, but who knows), arbitrary jpeg compression issues affecting Photoshop's perception of brightness, and questionable relation between Photoshop and real-world brightness. And I'm sure there are things I'm forgetting, but you get the idea.

So again, here's my rag-tag, get-the-general-idea runtime graph, run on 2x Tenergy CR123A primary cells:



Max output for brief moments, followed by regulation at ~65 lumens for 3+ hours, 50% brightness reached at about 4 hours, and useful light >7 lumens until about 9.5 hours.

Summary of the G2L

- Good brightness for 3-4 hours
- About 8 hours of 10 lumens of light, to serve well in emergency situations like blackouts. But if you're putting this light in an emergency kit, stick at least one extra set of batteries in there in case you do end up needing to go back to full brightness after the high output has given out
- Tight hotspot with very wide spill
- Good for throw within probably 50 yards; excellent for flood work despite having a concentrated hotspot (could get in the way for tasks like reading in the dark)
- Perfect beam: no rings, artifacts or other irregularities
- Perfect light for backup or emergency use

Well, I hope this review proves useful for at least someone out there, and/or has some interesting info/data for others who don't necessarily need a review. Please feel free to shoot me more questions to enhance my review of the light, or question my runtime methods, etc. etc.

Cheers!

Direct drive. Wow, we're so used to regulated LED's where runtimes are calculated by the time to 50% of max output. Surefire's rating of 12 hours must have been calculated to 5%.

Not impressed.

Thanks for the review. I like how you improvised to measure the brightness and runtime. Clever.

The tint looks awfully blue to me or is this due to your camera?

Supernam said:

Direct drive. Wow, we're so used to regulated LED's where runtimes are calculated by the time to 50% of max output. Surefire's rating of 12 hours must have been calculated to 5%.

Not impressed.

Click to expand...

This light isn't direct drive, the drop is the result of the thermal regulation kicking in so the lamp assembly doesn't overheat! Remember that this runtime graph has been made using pictures, at regular intervals, and isn't as precise as it would have been with a light meter recording data continuously.

Thanks for putting htis together zven. I just ordered the G2L and was planning on using it around the house or it may find its way into my auto.

Nice to see another Oregonian.

zven, good work. Looks about right for 80, or so lumens, with two CR123's. Three CR123 would be interesting ,also. Might come close to X2 runtime.

Bill

LA OZ said:

The tint looks awfully blue to me or is this due to your camera?

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Well, the light is noticeably blue, but I guess comparing it to what my eye sees it's a much less pronounced tint. I'd say it's a vaguely closer to a shade of violet (that's not to say it appears violet, though). Actually, the tint is really rather similar to the background color of these CPF posts, if that helps at all.

WildChild said:

This light isn't direct drive, the drop is the result of the thermal regulation kicking in so the lamp assembly doesn't overheat! Remember that this runtime graph has been made using pictures, at regular intervals, and isn't as precise as it would have been with a light meter recording data continuously.

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Actually, from my use of the light, the regulation only seems to be active for that first bright period (3-4 hours in the G2L), and after that it seems more like direct drive. It seems fairly clear to me that the regulation circuit isn't allowing the lamp to put out more than about 65 lumens because that's the best the LED can handle in the Nitrolon body. But the drop in output at ~4 hours didn't seem to be the result of too much heat; seems to me that if it were, it would have popped back up to a brighter level after the LED had a chance to cool a bit at the lower level. My understanding of that could be off, but on other cells that see intermittent use, the light has seen only a few moments at a time at the high output, and still after after about 4 cumulative hours of the high output it still goes dim, into that diminishing output mode; the diminishing output there can't be because of heat because the lamp has gone for many hours without use/heat buildup. And as a side-note, the head did feel significantly cooler after the 4-hour regulated period.

Heh, I guess that was a little long-winded, but what it comes down to is that from my observations the regulation circuitry in the P60L keeps the LED thermally regulated (and thus probably varies depending on the body material) for as long as the batteries have the juice to stay at that level. In the case of the G2L, this means about 65 lumens for 3-4 hours. After that, without sufficient power, it seems to drop to direct drive.

Keep in mind, though, I'm no electrical expert, and I have no reliable testing equipment to verify anything, but it sure looks like after that 3-4 hour regulated period, the batteries are the only determining factor on brightness.

To geeman, I definitely intend to keep this light in my auto (when I have one; at the moment I have no need for a car). But the light will certainly see indoor emergency use. Kind of makes me hope we get some monster rainstorms in the Northwest here, so that I can put this thing to use in a power outage...

And to Bullzeyebill, I'm also curious about the 3x CR123A runtime. I've dropped the P60L in my G3, and it seems to run fine and the brightness looks to be about the same. One of these days I'll probably end up doing another informal runtime test to see how the 3 cell setup compares. But in the meantime, of course, I'll hope that someone with more professional equipment could beat me to the task.

zven said:

Actually, from my use of the light, the regulation only seems to be active for that first bright period (3-4 hours in the G2L), and after that it seems more like direct drive. It seems fairly clear to me that the regulation circuit isn't allowing the lamp to put out more than about 65 lumens because that's the best the LED can handle in the Nitrolon body. But the drop in output at ~4 hours didn't seem to be the result of too much heat; seems to me that if it were, it would have popped back up to a brighter level after the LED had a chance to cool a bit at the lower level. My understanding of that could be off, but on other cells that see intermittent use, the light has seen only a few moments at a time at the high output, and still after after about 4 cumulative hours of the high output it still goes dim, into that diminishing output mode; the diminishing output there can't be because of heat because the lamp has gone for many hours without use/heat buildup. And as a side-note, the head did feel significantly cooler after the 4-hour regulated period.

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I know, I know! The LED is dimmed at around 65 lumens because of heat generated, and the LA keeps this level for the 3-4 hours. If the light stay cold, it will proably be brighter, but for less time. Then for sure, when the output diminish, it's because batteries are dying!

WildChild said:

I know, I know! The LED is dimmed at around 65 lumens because of heat generated, and the LA keeps this level for the 3-4 hours. If the light stay cold, it will proably be brighter, but for less time. Then for sure, when the output diminish, it's because batteries are dying!

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Heh, this is almost starting to make me want to test the G2L in a walk-in cooler or something. My summer job's got one of those, but I can only imagine the looks I'd get for setting an active flashlight on our dairy rack and periodically going in there to take notes on output...

Actually, come to think of it, the results of that might not work out that well; although the cold may allow the regulation circuitry to set itself higher, I noticed when I froze my G2L and L1 CREE overnight that they were a bit dimmer than usual. Then again, this could be because of condensation that formed on the outside of the lens that didn't wipe off very well... Again, another place where a fancy light metering system would help.

WildChild said:

This light isn't direct drive, the drop is the result of the thermal regulation kicking in so the lamp assembly doesn't overheat! Remember that this runtime graph has been made using pictures, at regular intervals, and isn't as precise as it would have been with a light meter recording data continuously.

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I think it's direct drive because the runtime chart looks incredibly like a typical incandescent lamp on lithium cr123's. Usually, when lights are direct drive, their discharge curves are dictated by the batteries.

I don't mind direct drive, but if you're telling me that the G2L IS regulated, then I'm not buying it (figuratively and literally).

All "Buck" regulated lights go into direct drive once the voltage of the batteries reaches the Vf of the LED. (around 3.6v, or in case of G2 ~ 1.8v per battery) That's just how it works.

People around these parts are more used to seeing the graphs from single cell Boost regulated lights. They tend not to have much of a tail, because as the battery voltage sags, current demand goes up which causes the battery to sag even more, which causes current demand to go up some more; a vicious cycle of near instant death. I prefer a long tale for emergencies. If you took those batteries out of the G2 at the 50% mark they probably wouldn't light up a single cell light for more than a couple minutes.

PS: How does it work on LiIon 17670? I know one will fit.

It's regulated. The level of light maintained for about 3.5 hours, and it was pretty flat. There's no direct-drive incandescent I know of which has a graph that shape - there is always a continuous down-sloping. This also matches up with data we've got from other sources (other posts by other members on the forum) - it's nice to see those Tenergy cells perform like that too.

cave dave said:

PS: How does it work on LiIon 17670? I know one will fit.

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Actually this is something I've kind of been wondering myself. Unfortunately I'm relatively new to this field, and haven't quite gotten to the "rechargeables" stage of my flashaholism (though I can see it approaching fast). And actually, I have yet to decide if I'll eventually want to go the 17670 route, or stick with RCR123's for more versatility in 2- and 3-cell body configurations. But I digress...

The P60L has true current regulation. You can test this if you have an ohmmeter. Placing one lead on the back of the rearmost battery and the other on the body tube, you'll see that this light draws about 360 mA at 6volts, and progressively more current as the batteries become depleted. At 9 volts it draws 240 mA, or 2/3 as much current draw.

The initial drop in brightness due to thermal regulation would likely be far less if the P60L were used in the aluminum bodied 6P instead of the G2L. In either case, I think it's a great light.

zven.....thanks for a fine review and for showing us a clever way to do a runtime test. I'd say your results are pretty darned accurate.

I know others have already said this, but that's an impressively clever way of doing a runtime graph! Nice review, too.

nikon said:

The P60L has true current regulation. You can test this if you have an ohmmeter. Placing one lead on the back of the rearmost battery and the other on the body tube, you'll see that this light draws about 360 mA at 6volts, and progressively more current as the batteries become depleted. At 9 volts it draws 240 mA, or 2/3 as much current draw.

The initial drop in brightness due to thermal regulation would likely be far less if the P60L were used in the aluminum bodied 6P instead of the G2L. In either case, I think it's a great light.

zven.....thanks for a fine review and for showing us a clever way to do a runtime test. I'd say your results are pretty darned accurate.

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That initial drop had me confused as well. So why do the Fenix lights or Lumapower M1, for example, start at 100% and stay there until the drop off in runtime graphs? A 20% drop in output is meaningful. That drop after several minutes makes it appear to me (a non expert) that regulation is weak. Don't lithiums/mimh's display an inherent plateau'd curve anyway? Clearly I don't understand thermal regulation, but have noticed that type of graph *edit* on the L1 "high" review and find the "sloped regulation" unappealing.

I am not sure if I completely understand what you're saying mx (so apologies in advance if i'm off base) But in the case of the p60L, the thermal sensor protects the led from overheating and lowers output to an acceptable level for continued regulation.

It makes sense for me (consistent with posts from others elsewhere on cpf) that after afew minutes of constant on the p60l in the g2 would fall down to a regulated 65 lumens or so. This is pure speculation on my part though

To test for this I would suggest turning the light off, letting it cool down and going again. Also testing it in a 6p to compare. As a number (including myself) of Surefire users mainly use them for momentary light (i.e. flash on, flash off) they would still have 80 lumens.

I can't comment re Fenix's and heat regulation management versus regulation etc.

lightemup said:

I am not sure if I completely understand what you're saying mx (so apologies in advance if i'm off base) But in the case of the p60L, the thermal sensor protects the led from overheating and lowers output to an acceptable level for continued regulation.

It makes sense for me (consistent with posts from others elsewhere on cpf) that after afew minutes of constant on the p60l in the g2 would fall down to a regulated 65 lumens or so. This is pure speculation on my part though

To test for this I would suggest turning the light off, letting it cool down and going again. Also testing it in a 6p to compare. As a number (including myself) of Surefire users mainly use them for momentary light (i.e. flash on, flash off) they would still have 80 lumens.

I can't comment re Fenix's and heat regulation management versus regulation etc.

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You're not off base . .i admittedly don't know what I'm talking about . . so your reponse is helpful.

I agree as you say that I would mostly use my lights in 1 second to 30 second bursts . . .so if it does in fact stay at roughly the highest output in consecutive bursts, then it makes a lot of sense.

I would still like to understand more about the impact of heat on led's . . and if perhaps SF is just ultra conservative v.s other mftrs. However . . . I recall owners of L4's/L2 commenting on the searing heat of the body after constant on . . but yet my aforementioned Fenix and lumapower stays coolto barely warm after 10 mins on. Hmmm. I'm not dissing SF as I much prefer my A2 to anything else and just ordered an L1 . . .but just interesting.

Whilst the effort creating the informal runtime graph is impressive, I would prefer to wait for several people to perform more accurate tests before drawing conclusions based on the graph information.

Al