I have a recent Olight M20-S (R5) and found out after the fact about its parasitic drain. I put some new Titanium Innovation CR123A into it about a month ago.. and now they are reading 3.0v with very light usage. I have been playing with the light, and do not see any lockout feature.
Any idea how long it takes to drain the batteries if just sitting around? Maybe I should get a 18650 for it. (got one for a SC600W)