just in case anyone uses the Magicshine battery that has a jumper/lead cable going to the light, if you use it as intended within it's designed functions, & you start to notice it flickering or shutting off randomly, it probably needs a new jumper/lead cable.
So far i've gone thru three & they all failed at the battery connection area. The plastic insulation around the red & black wires splits & shorts the circuit. Had one break the soldier joint & touch over to the other part of the PCB. Poor materials for a design that could go far, especially for the price.
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-YMMV