Surefire LX2 vs E2DL LOW Runtimes and general observations

Wurkkos

Simon520

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Nov 13, 2009
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Just thought I'd post some very interesting findings regarding the above lights.

I didn't see any actual runtime graphs on LOW level (correct me if I'm wrong), so I decided to run them myself.

THE LIGHTS

Both purchased at retail at Plaza Cutlery in Costa Mesa, CA. in June, 2010.

External packaging on the E2DL shows it's a 200/5 lumen model and the internal paperwork has a 2009 revision date.

LX2 is a 200/15 lumen model. Internal paperwork is Revision A 6-2009.

To me, the LX2 has a less defined but ever so slightly larger hotspot than the E2DL. They both have marginal spill (I'm a big McGizmo Haiku XPG fan) and rings at the periphery. The E2DL's hotspot MAY be a tad brighter, but when I swapped the LX2 head onto the E2DL body, I thought it was a tad brighter; it's probably not a detectable difference with the human eye. The E2DL head on the LX2 body results in a correctly functioning 5 lumen/200 lumen E2DL head with the LX2 UI: 5 lumen low first (lower than the LX2), then high. The LX2 head on the E2DL body will only run on high. You cannot fast click and get the low to come on. I prefer the lower low of the E2DL and will probably keep the E2DL head on the LX2 body.

BTW, I measured the tailcap resistance of the LX2 1st stage at 9.6 ohms. I can hear a whine (?inductor) in the tailcap on high.

Tailcap amp draws with fresh PRIMARY Surefire 123's:

E2DL: 800 mA high 32 mA low

LX2: 830 mA high 32 mA low which is 5.21 watts battery draw on high (well, it would be if the batteries don't sag and I'm sure they do a bit).

Both will run a bit dimmer on a single Li-ion source (4.2 volts); at this reduced level both lights have the same output and I cannot distinguish between the two. Both run down to 3.4 volts on an external power supply (pretty dim on high level), below that they extinguish.

THEY RUN ON RECHARGEABLES

Both run with 2x CR123A (AW brand rechargeable) with no stuttering or problems at all. They seem to be a bit brighter on the rechargeables; I compared the LX2 on RCR to the E2DL on primaries and the LX2 was noticeably brighter. Since they look equally bright when they're both running the same battery type, I take this to mean the lights are brighter on rechargeables.

Tailcap draw on 2 x RCR123A RECHARGEABLES (8.32 volts tested):

LX2: 530 mA High for 4.41 watts battery draw.

Tailcap draw on 1x RCR123A RECHARGEABLE (4.20 volts tested):

LX2: 515 mA High for 2.16 watts battery draw.

The LX2 and the E2DL will not light with a single fresh primary 123A cell. As mentioned above, they need above 3.40 volts on my meter to light.

The E2DL WILL fit an AW 17670 cell with the silver decal removed. The LX2 refuses to fit the cell under any circumstances.

RUNTIMES ON LOW:

My last observation is that the low level of both seems to result in the same power being sucked from the batteries- about 32mA. Since the LX2 has 15 lumens versus the 5 lumens of the E2DL, and appears to be least twice as bright, the LX2 seems to be the winner in that regard- free lumens. Surefire rates the low runtime of the E2DL as 76 hours versus the 47 hours of the LX2, but as I've shown, the amp draws appear to be the same and runtime should be identical.

I can see where Surefire gets the 47 hour estimate of runtime: 1500 mAH capacity in a primary divided by 32 mA draw is 46. Yes, I know there are 2 primaries in the light, but think about it- the math is correct.

I'm going to put fresh primaries in both and turn them on low and find out what happens:

E2DL: 22 hours to 3.5 volts and severe light flickering. After that, it appears to fall out of regulation and run dimmer. It ran another 4 hours in this extreme dim flicker mode until it was about 2 lumens and really too dim to do any tasks with (i.e. no longer "tactically useful light"). At that point, the battery voltage was 3.44 volts and it was drawing 7-8 mA. Testing with this unit showed it would not run under 3.40 volts, so the "moon" mode here would not last much longer. So, 22 hours of 5 lumen light then 4 hours of progressively dimmer flickering light. Call it 26 hours total useful low light. During the run, the E2DL got BRIGHTER at about 12 hours. Still not as bright as the LX2, but more than 5 lumens. When compared to an identical E2DL that had fresh primaries, the test light was significantly brighter. This was evident only for a few hours and coincided with the highest temps recorded on the E2DL.

LX2: Strong light at 15 lumens until 24 hours. Flickering evident but not as bad as the E2DL. Flickering actually stopped after a few hours. Started to dim ("run out of regulation") at 24 hours and get progressively dimmer but light stayed tactically useful longer since it started out brighter than the E2DL. At 26 hours, the light is still able to go to the brighter stage though I doubt it's more than 40 lumens at this point. The E2DL at 20 hours could not go into high mode. I did not record when the E2DL lost its ability to go into high mode. At 28 hours, when testing to see if the light would go into high mode at 28 hours, the light went brighter then shut off and would not come on at any level. When the batteries recovered for 10 seconds or so, it came back on low but at around 3-4 lumens estimate. I'd say the output is less than 50% of the original 15 lumen low mode, so technically the test should end, but there is still useful light at this point. In fact, it's still about as bright as an E2DL just out of regulation on low.


Interestingly, both exhibited the same phenomenon: the battery closest to the tailcap dropped its voltage much more than the other. The tailcap batteries on both were measuring 1.50 volts while the head battery was 2.20 volts. This may have something to do with the heavy flickering noted; it really was bad enough to compare it to a candle.

What I wanted to know was where was the extra power going that the E2DL was using? If it wasn't using it to make light, where was it?

The answer seems to be as heat. The E2DL at one point heated up to 98 degrees at the head. The LX2 never got above 84 degrees.

I'm happy that the initial tests I made showing identical 32mA draws on low pretty much were borne out with testing; the lights have very similar runtimes on low. The E2DL actually uses its batteries faster; its power converter seems to be less efficient at this 5 lumen level and wastes the extra power as heat. The LX2 at all times was at least twice as bright and ran longer with a much nicer non- or minimally flickering light.

In summary, the LX2 will run about 28 hours on LOW on primaries. It is "in regulation" for about 24 hours with no degredation of brightness until the very end approaching 3.4 total battery volts when you get some flickering. The light will then run "out of regulation" with a progressively dimmer light for another 4 hours or so. Even so, it's at least twice as bright as the E2DL at this point and the light is very useful. When it finally shuts off, let the batteries rest and you will get many more minutes of useful light.

The E2DL will run about 26 hours, but the output is significantly less than the LX2 at all times. My model has severe flickering after 20 hours or so that would be quite annoying if it were my primary light. The useful run time is 20 hours primarily due to the extreme flickering rather than the dimming light.
 
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sfca

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Aug 10, 2009
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Westcoast
Awesome! Really awesome. Thanks! :thumbsup:

I was always interested in the extra brightness with RCR123s - but the extra cost (Pila charger $50, AW batteries, ZTS battery tester), shorter runtime (> 1 hour?) and abrupt cut-off meant it was no good for me.

Seeing as I only use it max 5 minutes at a time and I love that big bright hotspot this is something I gotta consider in the future.

Oh - anyone (not just Simon520) got primaries vs rechargeable beamshots?
 

Simon520

Newly Enlightened
Joined
Nov 13, 2009
Messages
104
Location
Southern California
Awesome! Really awesome. Thanks! :thumbsup:

I was always interested in the extra brightness with RCR123s - but the extra cost (Pila charger $50, AW batteries, ZTS battery tester), shorter runtime (> 1 hour?) and abrupt cut-off meant it was no good for me.

Seeing as I only use it max 5 minutes at a time and I love that big bright hotspot this is something I gotta consider in the future.

Oh - anyone (not just Simon520) got primaries vs rechargeable beamshots?

If you have to go through all that to go rechargeable, I wouldn't bother. The increase in brightness is noticeable, but in real world tasks such as impressing the neighbors and illuminating sidewalks, there's not a significant difference. I have a $120 LiPo charger that I use but after testing my AW 139 2 bay charger, found that it is entirely sufficient (and safe) for charging my AW batteries. For around $20 delivered, you can't beat it. I believe the new ones don't even need the ball bearing spacers...:D
 

sfca

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Joined
Aug 10, 2009
Messages
572
Location
Westcoast
I just noticed something. How do we get the math for the increased output on rechargeables?
I've noticed lights tested at increased output with different batteries - even though the lights are regulated! Or, 1 battery type will run at lower amps (like 2.0 vs 2.2) then the other but still produce more lumens. :thinking:

I can see how XR-E will produce 114-122 emitter lumens @ 350mah. Using Cree's relative flux vs current graph @ 800 mah:
2.1 (210%) X 114-122 = 239-256 emitter lumens

With RCR123 vs CR123
3.7V vs 3.0V
550mah vs 750mah


And I'm lost
yellowlaugh.gif


?
 

:)>

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Tampa, Florida
Pretty crappy runtimes compared to the rated runtimes??? I love my LX2's but I really do hope that the runtimes are better than 24 hours.
 
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