Here's the thing.
The meter started kicking in tonight. It was about 60%. I took the batteries out and put it on my charger and the battery was discharged all the way down to 3.3 Volts. I haven't had any of my regulated devices (Flask(DNA40),IPV2,Hana(Dna30) go below 3.6 when the battery is at approximately 25% on the display which is where I usually change out the battery.
Wow a coincidence I'm rewatching pbusardo's with Brandon from Evolv and he's stating the lowest the battery will go down to is 2.75 volts.
I'm under the assumption that it's safe, but I still feel a little nervous letting the batteries discharge that low.
It's weird that you vapor flask shows different considering it's the same board (dna40). Maybe it's running and old firmware on the board and the newer ones use a different algorithm for determing what it should show on screen.
Reading the specs for the LG battery, standard safe cutoff for discharge is listed at 2.5v. So if the cutoff is 2.75, it's safe and within spec.
Also, officially all these batteries are rated at 3.7v. Discharge curves will show them sitting in the 3.9-3.5 range for a long time. So if the bar just displayed voltage, you mod would show it dropping to around half pretty quick, sit there a long time and then drop like a rock when battery is dying.
I bet the majority would panic at the start of the day if the bar showed half charge and charge there devices prematurely, which realistically may not be true in terms of how much vape time is truly left in the battery.