There is a couple videos of the H30 and othere Acebeam lights blinking three times when they hit 3.7V then shutting down and with different cells as well. Look up three blinks of death.
I thought I’d make a video to illustrate this very annoying “feature” of Acebeam flashlights. As the battery gets barely below 3.7 volts, and sometimes at higher voltages, the flashlights start to lose their ability to access every mode, as well as ruining the experience of using the lower modes by blinking. Sorry about the out-of-focus video and shaky camera handling. I don’t make videos regularly. [Acebeam Three Blinks of Death - Low Battery Indicator or Design Flaw?]