Proposal to get more battery life from 18650s

I noticed that I was not getting a lot of run time out of my 3300 mAH 18650s on T-Beams.
Turns out Meshtastic shuts off the device somewhere around 3.5 volts.

From what I can see online, a lot of 18650 batteries can be drained all the way down to 2.5-2.7V. I also read that this is not advisable as it reduces battery capacity over the course of months.

I also read that most batteries peak at 4.2V and usually go down to 3.3V and not 3.5V to get about 90% of their advertised capacity.

In the Meshtastic codebase, I see contradicting definitions in 2 places, not sure how to make sense of them.
My proposal is to let the device boot and work till it hits 3.2V or so, to get more juice out of it.

Please correct me if I am wrong with something.

Isn’t there a “supported” means of calibrating the battery?
But if the BMS is controllable via software, then this might work, but it would also shorten the life of the battery, no?
Different batteries will have different discharge curves, but most LiPo batteries start to flatline around 3.5 Volts and drop precipitously after 3.3 Volts. I’m guessing that the hazards of overdischarging a battery outweighs the advantages you’d get by drawing a few moar Coulombs out of a charge.
Making voltages user-configurable would be great, but Safety-Sally is probably going to remind us that it’s a bad idea. You’re probably “safe” at 3.3 Volts, but it’s really going to depend on the individual battery’s discharge curve. You’ll definitely wear then out faster.

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