Batteries last a long time!
Unlike the low cost 18650, the two I bought from Trustfire tested according to specification. This was three to five times the capacity of the cheap ones I had purchased on EBay, though the EBay ones advertised better specifications than the Trustfire one. Overall significant increase in capacity per unit cost.
_Capacity by SkyRC: 3070 mAh.
_Capacity by Opus: 3115 mAh.
_Internal resistance: 62 mOhm.
_Low voltage protection: 2.47 V.
_High current protection: 5.8A.
Discharged continuously with 4.5 A (delta), the battery only warmed up to 53 ° C.
And h = 69.17mm.
Liked the long range of battery charge for high luminous flashlights.
2xTF18650 2400mAh Batteries