100% agree, in parallel the danger is in putting batteries that are not of the same charge, or discharge at very different rates. If 1 battery is at 2.5 volts and another is at 4.2 volts, the low voltage battery will draw current from the fully charged battery, without regulation. The charged battery will discharge too fast and the low charge battery will charge too fast. If all batteries are charged and discharged together…married…it mitigates that risk. I know you know that but some may not. You would be better off with only 2 batteries installed than having 1 very undercharged battery. In parallel, slight difference will have the batteries all at the same charge level shortly as the higher charged batteries will drop and those batteries will charge the lower charged ones. That is ok if the difference is small, but very bad if very different, and it does this without even turning it on if there is no protection in the carrier. It is best to have batteries with the same or close IR, but 3 batteries of about the same age, and same number of charge/discharge cycles should be fine. Even 2 year old batteries can be used if they are the same. Just don’t mix old with new. If one battery of 3 married goes bad early, replace as a set and use the old ones as singles, but do not replace just the bad one. If you have other devices that use 3 21700 batteries, you can use a married set in it too. The batteries are married to each other, not the device. I label mine with date and a letter to indicate they belong together.
thanks sarge12! i have been using a letter system for all my multiple battery lights sets. im up to the letter "F" lol.
Here's the two together:
With sets of cells (got 2 sets of 30T's, 2 sets of 40T's):
Added an 18 AWG bypass to the driver spring:
Took some more measurements. I'm hitting ~1050 kcd on 30T's, and close to that on T50's, but only after ~2 secs, not 30 secs. Lumens peaked at 4960 at 30 secs (maukka calibrated), about 6000 at start.
Been finding that even if the light feels room temp, it's gotta to still be hot inside, because I get much lower readings if I don't let it pause for like 15-30 mins.
Tom E….I am still waiting for mine, but I was curious. Is there any real reason I would need the wire insulation if I add the bypass wire? Is there anything on that side that is positive that a non insulated bypass wire might contact? My spinal cord might make my solder job hard, especially if I have to be certain the wire insulation is not between the battery and the bypass. My hand shakes when doing something like that. It might be easier if the wire is tinned and has no insulation. Also, you can’t bypass the springs in the carrier can you? If you could would it even help?
For what it’s worth, my Fireflies E07X came with a bypassed spring in the carrier. If they take the time to do it I guess it must help.
- This is 18 AWG high strand count stranded wire - high strand count gives you more flexibility, though 18 AWG in short lengths isn't that flexible. The insulation is probably not needed to avoid grounding but it is needed to hold all those strands together, and also helps prevent the solder from creeping up the wires resulting in further stiffness - we want it to be flexible enough to take 100's of flexes on that spring.
- Don't have a pic but I bypassed the carrier springs in the proto with 22 AWG wires, same technique of looping around the outside, and have been using that carrier in tests on the production unit, until I get the production unit's carrier springs bypassed.
I usually bypass springs with a wire inside, but I wanted to use as thick wire as possible, and this spring is pretty short so space is tight.
These bypasses are certainly optional - the stock spring is high quality, but even the best springs get an advantage from a bypass. It made a big difference in the prototype, but still not sure about the production unit. The readings I took afterwards were somewhat mixed - I think between internal heat and battery sag, my tests were not clear and conclusive, and not made truly apples to apples. Who knows - might be hitting the point of no gain with the LED as well, if a SBT90.2 in fact has a point of high amps plateau effect - not sure we know where that is. It's probably in the range of 25 - 30 amps.
The 22 AWG wire on the carrier springs was much easier to work with, but again, I only use high strand count wire, usually Turnigy. Many times, the Chinese lights use a lower strand count wire which is probably cheaper, sometimes lower temp rating as well. You'll never find low strand count wire in Hank's lights - in fact I used to buy my wire from Hank when he was the best source for parts, hosts, and accessories, but not anymore because he dropped carrying all that stuff, now offering only options to his production lights basically.
Just got 2 different models of fireflies lights…E12r and t9r…wish I could love them, but the 10 click to advanced UI along with a bug in the UI on the E12r prevents that. For some reason I have to screw and unscrew the battery tube multiple times to get the E12r to work for the main led’s. The switch will turn on and off the auxilary led’s instead. It is buggy as crap. No idea who thought to make the simple UI default and 10 clicks to get to advanced UI for both, but it took me forever to manage that magic act. If not for the bug, and the making the simple UI default, I might like them. Unfortunately, I am left with my first impression being bad. Good gosh it is hard to click that thing 10 times quickly. No idea what might be causing the bug with the E12r either. It eventually works, but unscrewing it to prevent accidental button press is not a great option. After over 200 lights, this was my most dissapointing initial foray into a new to me brand. I have always read good things about them, but I will likely not buy another fireflies light based on this purchase.
Try performing a factory reset on the one that’s misbehaving.
I had an issue with a NOV-Mu which was acting strangely after a cell swap due to poor anodization on the threads causing the light to power on and off many times very quickly while removing and replacing the head. A factory reset cleared it up. Now when I switch cells I slightly unscrew the head to remove power, then remove the cell via the tailcap (which has unanodized threads). Not ideal but it works.
I don’t have any issues toggling back and forth between simple and advanced UI but I can see how it could be frustrating. To be fair, that isn’t really Fireflies’ fault; it’s the default behavior for Anduril 2.
Unfortunately, what's good for some lights and people is not good for others - I deal with this every day now at work, being involved in more customer and distributor support and feedback.
The 10 click thing came about from complaints of customers inadvertently getting into the settings and accidentally messing things up. Maybe not so good if it's an easy operation switch but some light switches are not made for that many clicks - they are hard to click by design, either the pressure rating of the mechanical switch is too high, the rubber boot is too stiff, or other constraints like being recessed, or the stack of the rubber to the switch has gaps, etc. I always always prefer easier operational switch for UI's like NarsilM and Anduril (2), but the manufacturers don't seem to see it this way.
I like the clear but I would probably get the black.
Thanks for the reply, but with my shaky hands, I guess I will just pass on a bypass wire. For someone who used to do wiring and often repairing PCB components even for a living, it is sad to think a simple wire soldering job would become so difficult. I used to do that in my sleep. It is super annoying. I used to build bridge rectifier circuits with diodes for converting AC to DC, now knowledge is a curse when I can’t control my shaking hand. I used to change and repair AC drives and field modules for DC drives, all of which required major Technical college courses. Today a simple light switch is a major job. All that technical training is a waste when you can’t control body parts. I don’t shake until I am doing something that requires being steady.
I am not real surprised that it retains a fair amount of heat internally. When you have a lot of thermal mass to transfer heat, it takes longer to heat up but also longer to cool down.
For testing a trick I have used is to put an ice cube on the fins of a light after it gets hot and it will cool the whole thing off real quick.
TA, do you by chance have a technical drawing of a length section of the WT90 ? I would like to drill some holes to attach a handle and I need material thicknesses at some positions.
If not, no problem, I can figure most of it out myself, but a drawing is way easier. 
Not sure that they want me to share those publicly.
Aha, so they do exist! 
Guess who just done got himself a new thrower??? Now just hours till I be singing “Hello darkness, my old friend…I’ve come to talk with you again” There is a song in that somewhere, shout out if you remember it. Edit:::It would be a like a “Bridge over troubled water” to name a remake of that song.
My favourite version of that song! -
Mine has just arrived also! After arriving into the country on the 30th May, it was stuck with customs for over a week! Thankfully no charges and it’s here safe and sound. Will take some measurement later. Very good first impressions! The thing is beautiful!
Direct Paypal payment?
It can be arranged if required. It is a bit more complicated but if you want to do that send me a message.
I used to think people were being genuine about the Fireflies criticisms (they might have been at some point in the past), but as of late, all I see it just a bunch of whine being served. No disrespect to Sarge, I’m just over the nonsensical Fireflies bashing. I realized people here are not being genuine or exercising good-faith when talking about Fireflies.
Fireflies is putting out the BEST lights right now over anybody. They’re actually still improving their lights, not just rehashing the same light over and over. E12R and T9R are better than the K9.3 and K1 from Emisar, and somehow that’s not good enough? And amazingly because Fireflies was one of the first to implement Anduril 2, now Fireflies sucks because Anduril chose to implement a simple UI in their software?
Then we even had that whole 10 page thread where everyone was losing their shit over the non-anodized threads. So many were acting like if their lights were absolute garbage because on the end of the flashlight that we ARENT EVEN SUPPOSED TO USE, there were grittier un-anodized threads? Make it make sense. That was literally the supposed MAJOR complaint of Fireflies this time around.
Much props to Texas Ace for bringing us a new light like the WT90 that actually excites. With LED technology hitting a wall, we need innovation and crafters like you and Fireflies that still seek to push the envelope themselves instead of waiting for the LED makers to do it for them with new LED’s. I’ve been trying to buy another Emisar/Noctigon for a year now and nothing over there has been exciting enough compared to my Fireflies. At some point some of you are gonna realize you got stuck buying too many D4v2’s while missing out on some other all-time gems.