Fireflies E07 preview

Can you measure the stock lens if it’s handy? How close of a fit is that?

Stock lens measures 35.00mm x 1.54mm

You made my day SKV89! Ordered two for my Cu and Cu/Ti E07s.

Jack told me that he is adding 20 degree E07 TIR optics for free with my order so I guess that some people might be interested to know about it.
The current E07 optic is 45 degree.

I’m waiting for it so I don’t know if the more throwy beam will look good.

I saw a more throwy optic on a site that I thought might fit the E07, but it was just a little too large. I wonder what kind of optic Jacky got.

I’d be interested in some for sure.

I received the UCL lenses for my E07s, and the are more clear than stock. The effect of the new lens is about the same as a LEE green minus 1/8th. The lenses are thicker though, so you will have a small gap between bezel and heatsink— it’s very small.

Also 45 degrees sounds very floody. I think current optic for ROT66 is 25 degree, and E07 is very similar.

That is what Jack told me in PM :

This optic (KingBrite) has the same 4 legs footprint than the E07’s one and have a wide range of beam angle : 10°/15°/25°/30°/45°/60°/70°
I’m not sure of the MOC.
I would have wished FireFlies to sell a few of them with the E07.

The E07 listing has always said 25 degree TIR but it will be interesting to see what you end up getting. Maybe something is lost in translation but either way more options are always nice

Wow 10degree would be awesome. Anywhere to buy just a couple to test?

I found out the mysterious reason why E07 drops in output overtime. The spring flattens out after being compressed and doesn’t return to the original length, which means it won’t push as hard on the cells. The weaker contact results in more resistance and lower output. I took some measurements with these fully charged cells. The 18650 cell uses a 21700 adapter, which makes them a good bit longer than the 21700 cells so the spring pushes harder on the 18650 cells.

Molicel P26A 18650: 6640 lumens
Molicel P28A 18650: 6300 lumens
Sony VTC5D 18650: 6300 lumens
Sony VTC6 18650: 5650 lumens
Molicel P42A 21700: 5600 lumens
Samsung 40T 21700: 5770 lumens
Samsung 30T 21700: 6500 lumens

This same E07 used to measure around 7,570 lumens with the same 30T and 7,017 lumens with the 40T. I swapped the tail cap with another E07 tail cap that is used less and the 40T measurements jumped from 5770 to 6000 lumens. There’s a possibility that I might have tried a 21700 protected cell which compressed the springs too hard causing permanent deformation, but I don’t remember. But now I know to never put protected cells in a flashlight not designed to accept protected cells.

These springs are not bad and all springs flatten out over time to a certain extent, but if Fireflies ever find any springs with better mechanical properties, they can sell them separately as an upgrade. There’s nothing we can do with the spring on the driver side but if Fireflies provide a longer tail cap spring, that will make up for the loss compression.

It's something we should all look out for on these high powered lights. I suppose good bypasses would solve that issue. Yet another good reason to add bypasses..

That’s the main reason I don’t like using BeCu C17500 45% IACS: while it does have better conductivity than BeCu C17530 38% IACS, its worse mechanical properties show up quite rapidly.

I tried to test a NCR18650GA button top and it crushed the springs further.
Now w/ P26A, it measures 5,820 lumens
Now w/ Samsung 30T 21700, it measures 5,840 lumens

This is significant considering the 30T used to measure 7,570 lumens when the springs were brand new. Lesson learned, be very careful what batteries you put in and twist the threads in slowly to make sure you are not forcing in a battery that is too long.

I would highly recommend to anyone with soldering skills to swap out the thermal paste in the Fireflies E07. I had 6500K SST20 inside and swapped them for Luxeon V2 4000K. I removed all the old thermal paste and replaced it with 10W/mk new paste. You have to unsolder all the wires because they are too short to be pulled out.

Before, the E07 got hot only slowly even if it was running on full turbo. It was barely warm at the outside and the heat would not transfer to the head as known from other hot-rods like the Emisar D4.

Now you can feel the heat at the outside already after a few seconds and it moves along the light until it is hot all along. That’s much better because if the heat is stored in the MCPCB the leds are more likely to fail. This leads me to the conclusion that Fireflies is using a much worse thermal paste than for example Emisar or Astrolux.

@Skylight Really? That’s the complete opposite for me, but I do have the V2 in which it has HY880 thermal paste.

The E07 gets hot insanely fast, even faster than my PL47, taking into account of course that the PL47 has a direct connection to the battery tube, so it doesn’t get as hot as fast, but the battery tube does get hot faster.

@SKV89, I would also agree. I advise anyone using any of Fireflies lights to not use protected/very long cells.

Like with Emisar/Amutorch lights, they use BeCu C17500 springs, so while they have some superb conductivity, their mechanical properties and resistance to plastic deformation(permanent) are bad.

I’m hesitant to say this because i dont want to start a thermal pastegate again but even on my Ti+Cu model only ~half of the MCPCB makes good contact with the shelf (FWIW my Emisar D18 was more or less the same). I added good thermal paste and it seems to transfer heat ok but obviously it could still be better.

My two early edition E07’s had virtually NO thermal paste

So if you have the skills - check

I wasn’t used protected cell, just standard length button top NCR18650GA with their 18650 adapter tube. Seems like it is only compatible with flat top 18650. I hope FF will increase the length of the tube slightly to avoid these issues and use the same springs you are using. That would result in the ultimate premium flashlight that should not degrade in performance over time.

On the Fireflies website it states this.

  • 7x CREE XPL HI V3 CW 6500K 6900 lumens Turbo brightness
  • 7x CREE XPL HI V3 3A NW 5000K 6900 lumens Turbo brightness

But isnt 5000K not as bright as 6500K?

If they are both V3 it wont be a huge difference. I think they have had v2, v3 and v4 in certain temps

It’s all about the flux bin. I’ve measured warmer temps brighter than cooler temps. If both of the lights are the same flux bin (V3), then their brightness should be the same. Though some lux meters seem to be more sensitive to cooler temps so they measure higher output with CW than WW even if the brightness should be the same.