An EagleTac (SporTac) single-mode drop-in has NO low voltage protection, or warning.
Wanted to know that specifically. Was confirmed by their CS.
In general you notice a light won’t make it to turbo anymore. Time to recharge!
But when it is already on, or/and unattended, it can bleed your cell’s down till the very end.
Most of my lights don’t have any LVP, or warning, at all.
And even when they warn you, chances are you are just looking elsewhere when the blip occurs.