Any ideas from the experts as to what the life should have been?
Most batteries will need a few (5-10) cycles before they reach their optimal capacity.
The temperature is well within the normal operating range for any battery, so I doubt that was the problem.
Keep some backup lights at hand and give these a few more full cycles.
If they keep performing badly, you may have a bad battery, which would result in a warranty claim. That could be fun.
Personally, if the battery turns out to be bad, I'd cut my losses and get something more reliable. Whatever you paid for that CREE knockoff isn't going to be worth the hassle and frustration that a claim will bring.
I'm currently testing a few sets of Lezyne Femto lights and am liking them very much.
Available in front and rear models, in silver, black, ano turquoise and ... yes, that's purple
The front ones have a normal backside, the rear ones have it at an angle to compensate for seat post angles.
5 modes, which is 2 too many IMO. I really like the slowly pulsating effect on the rear one though.
Video of the front one going through its different modes
I'm seriously considering keeping them on my bikes. I just need to figure out a way to get them mounted securely.