Important update:
Dear members,
I am sorry to inform you about a glitch in Sofirn‘s original discount calculation. Some orders were carried out using a wrong discount, higher than those advertised 15%. These orders are being cancelled and refunded by Sofirn. If your order was cancelled, I kindly ask you to place your order once again, using the updated code in the opening post. Sorry for the inconvenience.
Thank you so much for your understanding.
Thomas
Just curious, was there a change from the original first batch of Sofirn SP35 with this new “buck driver” design? Or is the first original batch of SP35 also have the “buck driver” design?
I ordered the SP35 during the 11.11 AliExpress sale, but due to long shipping times these days, my order is still in transit… (I expect at least another month before I can receive my SP35 unit from the 11.11 AE sale). So was wondering if that already has the buck driver or not.
Is there a quick way to check or test if the SP35 unit is the “without stepdown version” (other than doing a longer ceiling-bounce runtime test)?
The first batch of SP35 uses the new buckdriver but comes without thermal regulation. It doesn’t matter if you purchased from AliExpress or from sofirnlight.com. Do you have an IR thermometer you can point at the light when it heats up? In normal ambient conditions and without any thermal regulation in place the outer structure should heat up beyond 55°C after 2-3 minutes on turbo.
Maybe it’s not a bad idea to wear some gloves before starting the penetration test. :-))
Thanks for the info Lux-Perpetua.
I checked Sofirnlight.com which offers the SP35 with “No Stepdown” variant.
The listing for SP35 in AE doesn’t seem to indicate “No Stepdown” though.
Both item description do indicate the SP35 uses a buck driver.
How do we know which one is the No Stepdown version (is it only the Sofirnlight.com variant) if ordering the SP35 now?
(I’d like to try out both versions - the No Stepdown and with Thermal Stepdown variant ; I assume my first order 11.11 from AE is the No Stepdown version, if I want to order a new variant with ATR, any idea which one is the ATR variant? Or is that still to be produced in new batches?)
AFAIK, there is only the „no stepdown version“ with 800 pcs in total batch quantity available. I am not sure if Sofirn wants to wait until batch one is sold out. However, I highly recommend Sofirn to physically and logistically separate the next batch with ATR from the first version without ATR.
I feel that without ATR its kinda dangerous if its a new flashlight user / beginner using it. I would be interested to get one with ATR
Lux, i tried coupon code on Sofirn webpage but it says it’s expired.
No, not really dangerous, it heats up to close to 100 degrees Celsius and the temperature stays there. Way too hot to hold, not good for the lifetime of the flashlight, but nothing will fail.
Can it be used to burn paper? 
(sometimes people in our local flashlight community ask if I know of which (not too big, preferably EDC size or just a bit bigger) flashlight that can be used to “light up a fire” (make a piece of paper burn)… to which I usually just mention that higher-lumens flashlights usually can get hot enough to burn paper, but it’s not a “given” that burning will always happen — well I haven’t really tested that it does, but have noted some videos online that manage to use bright flashlights to produce a fire on paper…
Anyway with that side comment aside, how much estimated “lifetime” of the flashlight may be affected when it’s accidentally set to Turbo and the SP35 is left that way once or twice?
Once or twice or 10 times should be fine I guess, all the components inside a flashlight can survive 150 degrees, even the battery, although for the battery 150 degrees is close to failure.
But that is theory, in practice we flashoholics would be the least likely people to know how long a flashlight lasts. At least in my case: I have (way too) many flashlights but each of them gets minimal use, how would I know how they fare over time? :person_facepalming:
I have a Yootoo SD1 (modded with a LH351D) that I use as bicycle lamp, in winter it gets 5 hours of use every week. It is one of the least exciting flashlights in my collection but I do know that it works well and keeps working well. Same for the BLF-A6 that was my previous bicycle lamp.
A TLF member measured 103°C / 217°F after 15min runtime on turbo.
https://www.taschenlampen-forum.de/threads/sofirn-sp35.78231/page-4#post-1107360
Well, this kind of statement is in my humble opinion quite dangerous to leave uncommented. Depending on ambient temperature, battery age/condition/internal resistance and where you actually put the flashlight this can lead to a quite hazardous situation. Most (if not all) lithium-ion batteries are specificied to a much lower maximum temperature, especially in environments without temperature control. Normal operational surface temperature may be up to 60°C, in controlled environments up to 80°C i.a.w. specs from the manufacturer. It is unforeseeable what happens if a lthium-ion battery is exposed to more than 100°C for quite some time. Most likely, nothing will happen if you do this one or two times for a short period of time but I strongly disagree to say "nothing will fail". If things go south, you have a pipe bomb on your desk or worse, in your hands.
I can only emphasize again that this flashlight needs to be operated with common sense, i.e. once it gets way too hot to hold it's reasonable to step down its power manually.
There is a large gap between normal operating temperature limits and the temperature at which Li-ion cells are actually failing. From what I recall, the temperature at which thermal runaway is becoming a risk is for classic li-ion cells about 150 degrees (not unforseeable, it is tested), for IMR-cells and more modern chemistries a bit higher. This discussion is not about normal operation (you do not normally operate a flashlight at 100degC, that burns your hand badly) but a calamity, in which case you want to know when things really go wrong instead of the common recommendations.
Btw, I think that, if done well, thermal regulation is a good thing, although some manufacturer’s setting are so conservative that it spoils the functionality of the flashlight. But this discussion was: is it dangerous not having it on this light? And my estimation is that it is inconvenient but not dangerous.
...
I try to get us a new coupon code.
Sorted! Code works great, only i was dumb not to see it was applied and order went to awaiting payment section of my account.
Sorry for the trouble.
Update (OP is updated, too):
As Sofirn ships the current version of the SP35 without ATR with the manual of the SP35 with ATR, I took the liberty to revise the manual accordingly and offer it for download here:
Please click ► HERE ◄ to download the revised user manual in English.
Please click ► HERE ◄ to download the revised user manual in German.
Important notice: Please be informed that this updated manual refers to the SP35 without ATR. This version does not have any thermal stepdown!
Any idea if this will be coming out with a 50.2?
Very unlikely to happen in the new future. Sofirn is currently struggling to get ahold of the 3V XHP50.2. I wish there was a 3V XHP70.2 or MT-G2 to run with SP35.
Is this 6500k or 5000k? Why is it saying Sofirn can’t ship batteries to the US? I just bought some batteries a little over a week ago. What’s the deal?
I have trouble telling from beam shots if the SST 40 has a smooth beam or a distinct hot spot. I am not a fan of distracting hot spots for walking. Can you tell me your opinion please?