Fireflies E07 preview

YES! The trj20 thing. Thats what i was thinking. In copper.

Hi guys. I want to buy batteries in advance.
What do you advise?

Shockli 21700 4550mAh, Samsung INR 21700-40T (preferably)

I don’t know where did you get the 30s from. Myself I did a quick calculation based on assumption that turbo time is directly proportional to mass and inversely proportional to number of emitters. As I noted this method has flaws but should arrive in the ballpark of being correct.

You’re very wrong. I care about regulation and I care a lot about practicality. But I can live without the former and the latter is precisely the reason why I don’t like adding mass for mere improvement to turbo time.

My use case is to have just a couple of hundred lumens sustained. But I blast turbo to either get a better view of some area or to see farther. Usually 10 seconds is enough. Sometimes it’s not. But those cases are definitely not worth a weight increase.

“Maintain” means efficiency and heat shedding capabilities. Not weight. And 1200 lm is not turbo, it’s just a medium mode.
7 emitters give good efficiency, though with a different driver that could be better. On the head-shedding side the head is barely finned and quite small.
Effectively, I don’t see this light as a sustenance queen. I’m far from being certain about that though.

11.11 might be a good time to buy batteries.
Depends on the needs

  • Samsung INR 21700-30T - for max output
  • Liitokala Lii-40A - good cell for a good price
  • Samsung INR 21700-40T - very good cell, a bit better than Lii-40A
  • Shockli 21700 4550mAh - very good cell, not very expensive
  • Sanyo NCR21700A - very good high-capacity cell, though I would hesitate to use it frequently with a hot-rod like that

Myself, I have Lii-40A already (and no light to use them in :wink: ). If I didn’t have them, my pick would be Shockli 21700 4550mAh for runtime and 30T for output.

I like to add that the Sofirn 21700 4.000mAh seems to be quite comparable to the Samsung 40T at a very decent price. Maybe it will be even cheaper on the 11/11 sale. For maximum runtime I recommend the Samsung 50E cell with 5.000mAh.

thank you very much for the tips.

I said I suspect they will design turbo to last 30s, which is based on the ROT66. To me the calculations you claim to have made completely don’t make any sense. I don’t see how increasing the the mass in the head by at least 50% will only increase turbo runtime by 3s. If FF really designed Turbo to last only 12.5s as you calculated, that would turn away a good number of purchases. There were plenty of comments laughing at the 10s turbo on the Nitecore TM10K. Also the D4 and PL47 already fill the short blast turbo toy category so it would be a bad business decision to have the E07 turbo last only 12.5s and with probably equally poor sustained output. E.g., the D4 drops to 250lumens at 60s and below 200lumens a bit after and subsequently oscillating around 2xx lumens the whole way (depending whether tail standing or handheld).

As I stated earlier, if I had to choose, I prefer more fins over more mass. But preferably and optimally, mass should be added as fins where possible to increase heat dissipation; but to maintain the size of the light it seems not easy to increase fins. However just adding mass alone will extend low and mid power runtimes also, not just turbo as I showed in my posts above. I would much rather the light can handle a decent output for 30 minutes than 15 minutes.

You are restating to me exactly what I already explained in my posts above.

Adding mass extends steady output runtime and slows temperature gain at all output levels. I normally use my flashlights for 20 minutes or so at a time so if a flashlight like the TC20 can maintain 1,000 lumens for 30 minutes, then I say it can maintain 1,000 lumens for my typical use cases and probably most uses cases.

Right now, the 138g of the E07 is lighter than every single other light of its size class yet it is the most powerful one. Your own post here shows a list of other lights and they are all heavier. I have never heard of anyone complaining about any of those lights are heavy. Adding 40g to the head of this light is hardly noticeable and it will still be lighter than the majority of those less powerful lights in your list. I suspect most potential customers would prefer the very noticeable performance/runtime advantages from this hardly noticeable increase in weight. I already provided information from my own testing in my posts above how much added mass can benefit maintaining steady output and reducing rate of temperature rise.

I bought 4 ROT66, 2 PL47, but I will probably buy only 1 E07 if it is only good for 12.5s turbo, and probably equally poor low-mid level thermal/output performance. However, if the E07 has at least the same output/thermal performance of the D4S and preferably the C8F and TC20, I will probably buy a couple. My friends who use flashlights for work will surely ask me to order some for them if it turns out more than just another D4 toy.

These lights are so small, why not add 80g of mass instead and make turbo run times acceptable? It's not as if this light is going to break anyone's hand holding it from being too heavy.

I bought some Sanyo NCR21700A 5000mah Tesla batteries. They perform better than the 50E and 48G. You can read about it here.

Look at these comparison graphs, it can maintain voltage better than the other cells for the entire duration of the battery capacity.


I bought the Sanyo NCR21700A from “Vapcell Dennis”. The price is so low I will not post it here. Give him a PM on BLF. Also, you might want to order the button top version because the standard version is recessed and will not work with most chargers. The button top version adds some resistance so you don’t get the full 15A continuous rating.

If you want max turbo output, then get the 4000mah VTC6A or 40T. From my testing on the C8F 21700 and TK01 (both not as powerful as this light), I see literally no difference in measured peak turbo output between the VTC6A, 40T, and the 3000mah 30T and even if there is on a light like the E07, it will be hardly noticeable base on my experience testing numerous 18650 high output lights with different cells.

Weight wise, I think most people will have no problem and it would only cost literally a few pennies more to make. With battery included, it will still be lighter than most lights in that list. Even a Shockli 26650 weighs 96.8g. However, it might not be easy to increase that much mass without increasing size or going with copper and I doubt FF will want to make those kinds of changes. Personally I won’t mind the light being a bit bigger especially if fins can be added or deepened (it’s currently smaller than the D4S in every dimension) but I think many people would want it as compact as possible so adding at least 40g (to the head) would be decent.

I don’t have any data on how is the weight split between the head and the rest, so I assumed that each gram of light affects turbo time the same regardless of where it’s placed. Yes, this is not really correct as I stated before, but I believe that it’s much better than guessing.
BTW, according to TK D4 can sustain ~600 lm, though it indeed falls way below that right after turbo.

I use the word Turbo not to denote the highest mode, but any mode that can’t be thermally sustained. I know this is ambiguous, but I don’t see a better word. :frowning:
So under my fingers “Turbo” can include middle modes of hot rods. But not low ones.
Not-sustainable modes are the only ones that benefit from higher mass. Their runtime is directly proportional to thermal capacity, which is often closely related to weight (though it doesn’t have to be). Sustainable ones just don’t benefit from that, unless we’re talking about totally marginal stuff like Vf change with temperature during the time before the host is thermally saturated.

I won’t comment on whether 20 minutes is a long use for most users. I don’t know.

Yes, I think we just agree about that part.

Frankly, I don’t think there’s another light in this class yet. And I listed throwers larger than C8. That’s really not comparable.
Is a 40g increase “hardly noticeable” really? Let’s not talk 140 vd 180g, nobody will use this light w/out cell. It’s 210 vs. 250 grams. Now….is this “hardly noticeable”?
For me definitely not. I believe most would notice that easily. Would they care? I don’t know. I would.

I really don’t see how a D4 can sustain 600 lumens without active cooling. I just tested my D4 XP-L HI using my Texas_Ace lumen sphere calibrated with Maukka calibration lights and here are the results:
0s - 496 lm
4min - 256 lm
8min - 60 lm
12min - 31 lm

I’m not sure how Toykeeper calibrated her lumen measurement device but most lumen readings on BLF and manufacturer’s specs are much higher than ANSI certified lumens. Not sure if she got 600 lumen sustained under active cooling. I also did left it tail standing while waiting for the next measurement point instead of holding it throughout the test so it loses the heat sinking benefit from a human hand. The temperature of the light was pretty warm at each measurement interval. I doubt with a human hand holding it tightly will allow it to maintain anywhere near 600 lumens unless you set the allowable temperature to the max, which is not usable without gloves. Also these runtime measurements are normally conducted without a human hand holding the light. Almost everyone on BLF own a D4 so it can easily be confirmed. All you have to do is set the light to about 500 lumens calibrated with another light rated at 500 lumens (if you don’t have a measurement device) and leave it on the table. 10 minutes later, compare it with a 30 to 100 lumen flashlight and you will see how dim it is.

Regarding your concern about adding weight (210 vs 250 grams), I would say it would be pretty hard to tell which weighs heavier if you were given one light after another. Even if you were holding one in each hand, it is still not going to be immediately obvious. I just tested it comparing lights with similar differences. However, the performance advantage will be far more noticeable as I have described previously from my testing.

Of course it will step down… all the heat inside the tube will cause the light step down…

“Runnnnnnn! Gooooooo! Get to the Coppah!”

Guys … Another question about batteries …
I prefer a flat top batteries.
Do you think it would be a problem for FireFlaes E07?

A copper version of that thing will likely cost in the thousands. Also copper is relatively soft so not sure if it’s good for deep fins although those fins appear pretty thick. But that would be a super sweet light. Can probably handle any realistic output levels until batteries run out. You will need to do some dumbbell training to build up some biceps before you can handle that light though.

I have a tr j20 with the sst40 dedome… i break the lense… lol… anyone know where i can buy a replacement lense ??

I don’t own one. Was this a VN light? Is it using the stock driver or modified? How many lumens does it make?