Fellas, this one is an X-File! I've got a two cell (18650) Solarforce that I run most of the time with one. I've notice that while running the light with one cell, I get this ringing or osillation noise coming out of the battery. And it doesn't matter the brand of 18650 cell I'm using! But when I add the attachment to make it a two cell light, the noise is gone! Has anyone run into this one? It's getting a little scary!
chiphead
chiphead