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.
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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?
AFAIK, it’s 6000-6500K. IIRC, they are still selling the first batch that comes without ATR.
Shipping single batteries has become a real problem for many logistics service providers, at least for air freight. For air transport these batteries are considered as dangerous goods. Legal restrictions are much stricter now, so there are few companies left and they probably charge a leg and an arm for shipping lithium ion batteries. It is easier to ship batteries while they are inserted in a flashlight.
I am not sure if this answers your question but I don’t mind to have a throwy light with a hot spot in the beam while taking a walk. It depends on the user’s preference and the environment. If I had to walk along a convoluted foodpath and if it was misty outside, I would rather pick a floody flashlight or headlamp to only light up the area in front of my feet. I have made good experiences in using a floody headlamp around my neck and a handheld flashlight for medium/large distances.
Concerning SP35 in particular, I cannot tell you my opinion yet as I do not have a sample of it.
Very smooth beams usually come from TIR while reflectors usually have some sort of hotspot. If you want to get away from a hotspot, you probably want a light with a TIR.
You commented right after I posted beamshots in my review of the SP35 so I figure you’ve seen those, right? I feel like it shows a pretty distinct hotspot.
Thanks.
Sofirn should consider offering this light with LH351D, although I suppose that creates competition within the product line. I am not interested in low-CRI EDC lights, but I would buy an LH351D version.
I originally considered swapping a LH351D into mine, but decided not too. Pushing a LH351D at 6 amps is past it’s peak and well past it’s sweet spot.
It probably won’t be anything revolutionary, but I ordered some 3V XHP50.2 to try in my SP35. I’m curious in the impact on raw output (lumens) and to see if it runs any cooler in Turbo (depends on how the vF compares vs the SST40). We’ll see. I know the beam will be ugly but I can’t help playing around.
Just curious, what is a safe sustained max current for an LH351D (assuming somewhat properly cooled)?
I tested tailcap current of SP35 (with a nearly full charged battery), and getting around 5 Amps max current consumption on Turbo mode (using a UT210E clamp meter), with a nearly full-charged 21700 battery. (although I’m not sure if the power consumption will vary depending on battery voltage for the SP35 — since it uses a buck driver.)