Hi all, I use eneloop xx in my fenix tk41 and they work well. Now my usual cheap blood pressure machine batteries ran out so in I pop four freshly charged hardly used eneloop xx only to find they were not up to the job.....or was it my b pressure machine that was faulty. Well I got four of the cheapest duracell from pound land and they work the machine so well. Is this because they are 1.5v and the eneloops are 1.2v? I don't know much about batteries, but I must admit I was a bit disappointed. Comments appreciated.