OP,
Who did you buy this light from? I find it difficult to believe Sofirn would have told you you need “protected button tops” for this light. Not sure how much more proof you need to know the cells you have are too long to work in the SP35.
Here’s mine. I use Samsung 40T flat tops. Sofirn also sells their branded rewrap flat top cells, also a good choice. Note the depth of the cell in the battery tube. This allows the tail cap to completely seat against the unanodized end of the tube to complete the circuit.
Now compare this to your situation. Those cells you have are probably 8-10 mm longer than the examples I gave, and clearly protrude from the end of your battery tube, preventing the tail cap from fully seating. Thus, your light won’t operate.
Just trying to help.
TIFisher's above post clarifies the issue with pictures.
For the Sofirn SP35 (which has a spring in the tail cap and a pad on the driver), before the tail cap is installed, the battery must sit below the cylindrical edge of the battery tube by about 3 mm or the tail cap can not screw on enough (because of the space required for the compressed tail cap spring) to complete the electrical circuit.
In case you are not aware, the "black colored anodization" on the threads of the tail cap, flashlight's head and body tube is an "electrical insulator" and will not conduct electricity at the relatively low nominal voltages supplied by the battery. Because of this, to conduct electrical current, the tail cap must be completely screwed on until its inside shiny non-anodized aluminum face touches the shiny non-anodized bare aluminum end (on the cylindrical edge) of the flashlight's body.
The advantage of having non-conducting anodized threads is that you can "mechanically lock-out" the flashlight by slightly un-screwing either the head or the tail cap from the body tube when you are not using the light so that it will not turn on unexpectedly while it is in your pocket or bag.
Makes sense. Since the driver does not have a spring, any battery that protrudes beyond the end of the body will prevent the tail from making contact to complete the circuit.
To clarify, I bought the SP35 directly from Sofirn. Since I accidentally ordered the one without included battery I asked them what kind of battery I needed. They responded that I should get a button top one. That’s why earlier I said there must have been some mistranslation.
Right now I’ve send sofirn another email with pictures and links to point to me exactly which one I need. If this doesn’t align with what everyone is saying I’ll just get in the car and go to a physical shop and have them try out
I’ve told the battery shop that I had this problem and that it’s fine if they dock the return value of the batteries. I don’t have any use for them and I don’t want to keep unsupervised Li-ions in the back of a drawer. Just a shame because I thought a 5000mah monster with integrated charging port was really cool, albeit just as a gimmick.
By the way I’m surprised at how quick and plentiful the helpful responses came from everyone. I guess this must be a caring hobby community, which is cool!
The battery shown in the link from Sofirn is typically referred to as a "flat top" battery and is not technically a "button top" battery.
Sofirn sells both "flat top" and "button top" batteries and their "button top" batteries do not look like that battery, they look like this instead (here is an 18650 battery for example):
