On a light with no low voltage protection

What is the consensus for assuring your not letting your batteries get to low , volt meter ?

Protected cells would be useful however, if you’re able to check regularly, yes, a DMM is fine. As a last resort, if you’re using the light on high, AS SOON as it starts to dim, it’s time to stop. Dimming would be harder to notice with lower modes.

Most LiIon cells have 2.5V end discharge voltage and white LEDs have a threshold voltage of arround 3V so virtualy no current at 2.5V.

So if you are not keeping your lights on for weeks without looking at them I would not worry about the batteries.

Good info in the above posts but also depends on what light you are running it in.

There are some lights designed to also run with AA or other Lithium primaries which will operate in "boost" mode and drain the battery well below 2.5V.

For examples - my Sunwayman V11R, Thrunite Archer, Balder SE-1.

But for a Li-Ion only light, significant dimming coupled with a little common sense will guide you.

Lastly, if you have drained your cell completely, try not to leave it in that state for extended periods, but rather, get a little charge into it to bring the voltage up a bit as soon as you can.

That’s what I was alluding to don’t want to drain my batteries too much supposedly not good .

If you have multiple cells, then draining too much is not an issue. Partially draining a LiIon cell does it no harm so if you use the light for ‘X’ amount of time and guesstimate that the cell may be half way dead (based on experience or calculations from provided specs,) change it.