Thank you for taking a deeper look inside the driver specs, Gabe. :THUMBS-UP: :BEER:
On a side note regarding Andúril, I was told that manufacturers may soon run into a major bottleneck for MCUs compatible to Andúril, probably even the old ATtiny85 chip. It is uncertain how severe the impact of this bottleneck will be and how flashlight makers will address this issue.
Concerning SP35's runtime: On TLF I was tought a lesson today by another member. He said the entire runtime specs in the ANSI chart did not add up. Provided that Luminus SST-40 consumes about 2.5A at 1000 LED lumens (excluding losses in driver efficiency) it seems impossible to reach 3.5 hours runtime at rated 950lm on High mode. Taking losses in efficiency into account (approx. 15-20%) the real output of the ATR version is apparently far lower than this. I don't want to argue about his assessment, also because I cannot measure any actual lumen readings.
My layman assumption i.a.w. the datasheet (6500K) is:
650lm @ 1500mA or 1040lm @ 2500mA forward current
I measured 2h 55min runtime on the ATR version with a 5000mAh battery. Without losses in efficiency the power consumption should be less than 1750mA. This would be equivalent to approx. 780lm constant output on High mode. This assumption does not take into account: full capacity by discharging the battery down to 2.5V, losses in driver efficiency, losses due to reflector and glass lens. If I deduct a loss of 25% in total for these variables it would result in actual 585lm OTF on average on High mode. Due to these fluctuations the output could be jumping between 670lm and 470lm. IDK, maybe my calculation is too pessimistic or maybe Sofirn got a higher flux bin, much better than average specs on the datasheet. I would feel much better if someone more experienced in this were to verify and comment on this. :-))
I also believe this to be true. I’m nearly out of attiny1616; I think I have ~5 left. The usual suppliers are out of stock. I’ve got an order in at Mouser, hoping to receive some in the next few months. Most of the other attiny’s are also out of stock. It looks like there’s a few of the attiny85 to be had, but not many. I figure if the big automotive companies are shutting down their production facilities (such as those used to build the F-150) then we truly are in a crunch and the “little guys” don’t stand a chance at getting the chips they need.
The ATR version comes in a 24 with the 40% off coupon. There is a coupon code for the non-ATR, but it is not that great. I paid 32 I think… or I got the wrong code. Either way - worth it in my book.
For those of you who like to see the difference between the first 100pcs of SP35 (w/o ATR) and the latest revision (with and w/o ATR) with improved reflector, I took two whitewall shots (WB: 5400K) today. Personally, I think Sofirn did a good job here. The revised version sacrifices some peak intensity (and range) in return for a more appealing beam shape mostly free of artifacts which also suits to the form factor of this flashlight much better.
My updated SP35 with “working” ATR showed up yesterday. I still think the SP35 is an amazing light & value. That said… my first runtime test is underway and (as expected) I’m seeing the same swings that Lux-Perpetua observed. I wish a little more focus was put to improving the ATR algorithm to help smooth this out.
The peaks are, on average, 1 minute and 45 seconds apart. The ramp up and down is very smooth; swinging between ~500 and ~1000 lumens. So in real life, it’s really not as noticeable as this graph might make you believe.
Once the tests are done, I’ll overlay graphs of the ATR and non-ATR versions and post those up.
I wonder how it would behave with fan cooling? Just thinking about which PID parameters should be adjusted. My guess is the fan wouldn’t change the amplitude much, just the mean output. Could be wrong…
On second thought. It might ‘raise the valleys’ by cooling the light faster once current is pulled back. This is of course based on an assumption that light to air conduction + radiation is much slower (ie limiting) than internal conduction.
I’m with you on the second part. It would likely “raise the valleys”. With regards to PID, I doubt that is relevant here. I imagine it’s more of a “ohh, too hot! now too cold!” algorithm without a bunch of extra math/prediction.
I bet you are right. In that case. There could be a simple two stage method. Let’s assume its 50c target. Set a ~2 degree window with a low gain value, then beyond that a high gain. If these two gain values are tuned, oscillations would reduce like a pid initially and then reach a continuous low amplitude ring.
Compared to a real world scenario SP35 acts like someone driving a car on the highway, frequently pressing and releasing the foot on the gas pedal to keep an average speed.
I also noticed that other flashlights allow a wider tolerance for their ATR threshold, especially after turbo is triggered. For instance, Acebeam L17 allows up to 70°C excess heat during the leveling phase before the ATR threshold settles at 55°C.
Sofirn‘s SP35 with ATR or even their new TF84 model have a very conservative, strict throttling. Consequently, the rising temperature is being reduced in an early stage to prevent significant overheating above the set threshold of 50°C (SP35) or 45°C (TF84). On a positive note, customers would probably complain less about flashlights getting very hot.
Got mine yesterday. Overall really like it. The size/power/price combination is just perfect. The ATR is very acceptable. Running flat top VTC6 with no problems and no rattle. For $24 with battery its just about the best deal in town.
Little beam comparison between new and old reflector.
Visually for me the new reflector has a larger hotspot and more smooth transition from spot to spill. Less tint shift and artifacts. I absolutely prefer the new one!
I’ve run full tests on both Turbo and High using the new ATR version (as well as the non-ATR version).
Turbo without ATR: gets too hot to handle in around 5 minutes
High without ATR: runs great, temperatures are fine (at least in a 21°C room)
Turbo with ATR: bright, but regulates down before temperatures get out of control; it ramps up and down to maintain a safe temperature (avg 54°C)
High with ATR: for some reason, output seemed a bit higher than on the No-ATR version and it gets hotter faster, then it begins oscillate much like it did on Turbo.
While the ramping up and down looks crazy; in reality it doesn’t actually look as bad. I just shot a video and will have it uploaded soon.
Here’s a nice, long, boring video of the ATR version running on Turbo. It’s exposure-locked so that you should be able to see fluctuations. The thing is, they’re so gradual that you can’t really see them. Each up and down cycle takes 1.5+ minutes to complete and is very smooth (not stepped).
Thanks a lot for the interesting and detailed analysis, Gabe. Glad to see that my observations are being confirmed in most points. I only wonder why my sample only ran 2h 55min on High using a fully charged 5000mAh Samsung 50E battery while yours ran outstanding 3h 11min with only 4000mAh. Can you please reconfirm that you used the Sofirn 4000mAh battery?
I also noticed a completely different „phase out“ behavior between your sample and mine. While yours shuts down very quickly at the end mine slowly reduces its brightness over a course of 30minutes. Any idea what can cause such a huge difference? The 50E I used is about 2 years old and had only a couple of cycles yet.
Regarding these brightness fluctuations I agree with you that these are barely noticeable outside „in the wilderness“ ;-) but looking onto the white wall I could easily track them with my bare eyes. While most customers not knowing about these fluctuations may not complain I still hope that Sofirn‘s engineering can tweak their ATR for a more stabilized output.
