You don’t say your cell’s chemistry. Lithium is in most batteries nowadays, but different chemistries have different specs and requirements.
LiCo cells prefer a 3.7v low limit, which is their nominal voltage. Below their nominal voltage, usage can only be low C-rate to avoid thermal build up, and each cell should be monitored individually. That is because below nominal voltage, LiCo cells are inconsistent, thus loosing balance quickly.
I know many LiCo cells are spec 3.0v cut-off (even seen 2.5v), but this is theory. In practical usage, they really don’t like lower than their nominal voltage, and they have little capacity left at that point anyway. Best is to have a battery big enough, that you never have to use all of its voltage operation range.
Lithium is pretty aggressively reactive, best safety measure is to monitor cells temp and to know the comfort zone of your specific cells. Set a battery temp alarm, or build to have temp in sight at all time during charge and discharge.
