Out of curiosity, I just checked a few SureFire 123s right out of the crate. They were right around 3.25V. I'm sure that comes down a bit as soon as they are loaded, but got me to wondering how tolerant our NODs are. Can someone inform me?

Anyone?

If you're measuring the open circuit voltage without any load on a brand new CR123a battery with an "nominal" voltage of 3.0V, then 3.2-3.2V would be expected.

Once you put a load to the battery, the voltage will sag a bit an hit closer to the "nominal" voltage number of 3.0V

The open circuit voltage on all batteries at full charge is always a bit higher than their nominal, marked voltage.  For example, I just pulled a couple new AA batteries out of my drawer and measured them, both have a nominal voltage of 1.5V.  The Duracell Alkaline measured 1.6V and the Energizer Ultimate Lithium measured 1.8V.

Many NODs regulate the voltage anyway, so some decimals here or there won't do a thing. Many CR123's I've used seem to show ~2.75 (unloaded) when they can't anymore power two tubes. One yes, two no. While the consumption is just tens of milliamps, close to the cutoff the volts start dropping rapidly and actually you get a huge boost in low batt run time if you shut down the other tube.

I understand that. Can you tell me if voltages slightly over 3.0V can damage my gear or not?