Allright, in the meantime I did some more research and tests.
I found a 32v power supply and tried the LED. It worked, so LED is fine.
This also confirms the LED itself. It should be a 30-36v LED with a max of 3A.
I measured the boost converters (?) output again a couple of times but instead of the previous 12v it gives me 44v now. Seeing 36v should be the max for the led I didnt dare trying with the risk of frying it.
I also really dont understand what changed so that it gives a different output.
Its fully encased in what I believe is sillicone so it can’t be a loose contact or short.
To elimitate the batteries I ripper it out of the case, hooked it to a 12V 2.5A powersupply and got the 44v again. Tried to remove the sillicone to see if I can find markings but that’s not going so well. Can share photos if needed for the parts that I could clean.
I discharged the batteries 500mAh with my accucel 6 and after this the charger noticed it could charge again. So charger and batteries are working.
So it would seem I need a new converter? Or is the 44v output normal due to not having a load and is the problem mysteriously solved?
And if a new converter is needed, what do I need? I’ve seen things about constant current and constant voltage, not sure what I need. Seen dc-dc converters with configurable output for a few bucks local, but also for 40/50 euro. The cheap ones are rated for 15 watt so that wouldn’t be enough I guess, or is that not comparable with the LED output?
And when I find something. Do I need to encase it again like this was? Would lots of hot glue work or do I need to buy sillicone?
Hope someone is able to give me some insights.