[Technical discussions] Sofirn SP35 - SST40, 21700 size, buck driver

Probably they would name those SP35 pro.

Businesses can be good and some things, but not others. Those strengths and weaknesses determine their level of success, or lack thereof.

Obviously, the company possesses the level of competency required to design, build, and market their lights to a good degree of success, certainly with the enthusiast crowd, and likely with the online consumer market at large as well.

Product marketing is not among its greater strengths, and the product management for the SP35, ranging from the confusingly recycled name (Why not the unused SP34? Perhaps a numerology thing, but the company’s model nomenclature have never had much logic, so who knows?), technical bugs that escaped the development phase and into production, and ultimately, performance shortcomings in the final “final” product exposed the weaknesses in more than one area.

One can only guess at why that is, without knowing the company structure and its development and production processes, but such issues are solvable. But, only if the company recognizes them and desires to improve. Personally, I’m with those who like the products, and the company, but with some frustration, and see some unfulfilled potential.

I’ve beat on this horse before, but the flashlight market hasn’t been hurt by products that are marketed in misleading ways, and don’t live up to their inflated marketing specs, even amongst enthusiasts who should know better. So what incentive is there to improve or do things any differently? Especially if it costs more and eats into profit?

Whereas the firmware issue with your SP36 could reflect a careless production worker using the wrong files when preparing drivers, the first non-functional ATR, and then underperforming ATR in the SP35 reach further up the chain.

Fortunately, I’ve never really had to deal with a complex customer service issue, technical or otherwise, and those of a minor nature have been handled well by the company, as long as the “right” party is contacted. But, knowing who that is can be confusing, and frustrating if that party is non-responsive.

One thing that piques my curiosity, and to me, really deserves more transparency, is the web of players involved with some of these companies, what their true relationships are, and how they operate. Some, like Convoy, are simple. It’s Simon’s business, his shop, and nobody else speaks for or represents him. Others, like Sofirn, have multiple sales outlets that operate independently, and multiple people speak for the company, with it not entirely being clear in what capacity.

But, back onto the topic at hand, the irony is that whatever resulted in the first SP35 production run, lacking a major feature, actually resulted in an arguably better product, at least in the right hands.

What was it? 30% amplitude difference at high mode? Who would notice that without luxmeter? How much time should Sofirn invest in flatten beautifying the curve?

I could easily notice it with my bare eyes even on High mode, no luxmeter required. Especially on lower brightness the human eye becomes more sensitive to output fluctuations. As always: YMMV!

My aspiration is to help them becoming better, not worse. I am sure they can improve things here without the necessity of redeveloping everything from scratch. It probably takes some tweaks on their algorithms, that’s all.

You sure be right, I might underestimate that.

If it’s anything like their SP32A V2.0 (one of their other buck driver lights), it’s using a 10-pin PIC chip which isn’t so easy to retrofit Anduril onto. Once I do my comparison of ATR vs No-ATR, I might have to take one apart and get a closer look at the driver.

As far as the runtime on High goes… notice how my No-ATR version “only” lasted 2 hours and 15 minutes? I feel like that’s pretty respectable, but nowhere nearly the claimed runtime. If ATR were even more aggressive (not that I want that!) it would indeed last longer. So perhaps that’s how they arrived at 3h 40m? Dunno.

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 received my non-ATR SP35 yesterday and won the battery lottery (5000 mAh) as well. I think this is a great light overall and a great value.

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. :frowning:

For $24, no reason not to get it.

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.

Nice, the new one looks 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.

IMHO, they (also) need to put more focus on the hysteresis effect with regard to thermodynamics and dissipation of excess heat.

https://en.wikipedia.org/wiki/Hysteresis

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.

I just had a look at that listing and maybe they changed it but it’s got ATR in title listing & description. :frowning: