Lower the cut off?

[JaI Haze]

If I lower the cut off to say 2.9 how much of an effect long term will it have on the batteries?  I know thats really low and at the point of damaging the cells but what kind of numbers are we looking at.  Will it totally destroy them?

[VapingBad]

It is the under load cut off so you batteries will not stay that low, it should be fine with most 18650s but probably too low for LiPos.  It will shorten the life of your batteries a little, but IIRC less that the difference between charging to 4.1 V vs 4.2 V which can double their life.  Have a read of this for fuller info http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

[JaI Haze]

so it will hurt the batteries, that was my concern

[VapingBad]

"it should be fine with most 18650s but probably too low for LiPos"

[JaI Haze]

oh ok I was misunderstanding it because this "It will shorten the life of your batteries a little"

[IMoL]

It *may* slightly shorten the life of your batteries, but I never worry about that.  Batteries are a consumable, like wire/cotton/juice - they will never last forever, whatever you do.

Is it *safe* to discharge 18650s down to 2.9 (under load)?  YES

Personally when running with 18650s, I set the cutoff to 2.8 - when I remove the batteries they generally read at 3.2 on the charger.  When running with LiPo, I leave the cutoff at 3.09.