Klarus XT11 won't work on Nitecore 18650

I have a Klarus XT11 and usually use 2x CR123s to power, but as this produces an audible inductor whine, I thought I'd try it with an 18650 as I've heard this results in a slightly less max output, but no whine.

The Battery I used was a Nitecore 3.7v 2600 mAh protected PCB, which I thought was a pretty decent battery which works no problem on any other light I have.

Has anyone else had issues where a certain brand of battery results in no power, but a different one works fine or does it seem like a fault with the flashlight?

Thanks for any thoughts.

I have used aw, trustfire, and generic 18650 batteries from a disassembled 18v Makita tool battery pack. All work with no problems. I don't know about Nitecore batteries but I don't see why they wouldn't work.

Update on my earlier post.

I bought some cheap Ultrafire 18650 batteries from ebay to see if it was the batteries or the torch which was at fault and the Ultrafire batteries work a treat.

Have you checked the battery voltage? Its possible the protection is tripped.