My SolarStorm X2 has a really aggravating characteristic: from full charge it runs for 1:40 on high setting with three green indicator LEDS displayed, two minutes more with 2 LEDs displayed, then abruptly shuts off. I discovered this the hard way, of course (i.e. on the bike, dark, r e a l l y dark road, but fortunately very close to home at end of ride). My guess is that I have badly mismatched cells in the battery pack.
Other than that, it's an excellent light.
Buy cheap... buy often....
Update: I pulled the shrinkwrap off the battery pack to investigate. There is a circuit board with leads to all three contacts on this 2S/2P battery pack, which has to be a good thing. It looks like it it simple 2S overcharge/undercharge protection. After four hours on charge with battery "full", no balancing occurs. One pair of cells was at 4.18V, the other at 4.04. It took 515 mAH from my RC LiPo charger to being the low pair up to 4.18V.
Endurance test in progress now....
End of test data: 3 lights => 2 @ 2:11.
2 lights => 1 @ 2:15
Sudden stop (no flashing) @ 2:18.
End of test voltage 3.34, 3.54 V
Last edited by no sweat; 05-28-15 at 07:22 PM.