I posted 2 new lights I recently bought – a Guard Dog Halo 290 which came with a 18650 battery and charger; and a Olight M20SX Warrior which came with 2 CR123A batteries and also takes 18650’s. I figured since I had a the charger from the Guard Dog I only needed a battery and would keep the CR123A’s for backup. I ordered a Panasonic CGR18650CG 3.6v 2250mAh battery from Amazon. http://www.amazon.com/gp/product/B001WBH2NE/ref=oh_details_o08_s00_i00 It doesn’t say that it’s protected, so I will assume that it’s not. There’s not a lot of info on the battery & charger that came with the Guard Dog either? After reading about the hazards of overcharging and overdepleting these batteries I’m a little gunshy about having them just sitting around. They are both single battery lights and it seems that a lot of the incidents have occurred with multiple batteries. So, to wrap this up, how can you tell if an 18650 is protected and I guess you really have to monitor your charging of these batteries? Thoughts on using the Guard Dog charger with other 18650’s? I guess it’s a good thing I’m a little OCD and recalled reading about not overcharging these batteries, because normally I would have put it on the charger and taken it off when I thought about it? There’s no info provided in the instructions about the potential dangers, which is a little upsetting. Thank goodness for this place and others I frequent.