Good question! 

I didn't vote because I haven't done the research on the subject.

3.8V is typically 40-50% which is good.
Storing a battery near dead is worse for its health.

Low end 3.4X, high end 4.1X. I’m not picky, my batteries will outlive me. I do meter them once a month or so just to make sure nothing funky is going on.

(Didn’t poll cuz I can’t figure out how to do it without losing my post.)

i prefer low but i do not put any effort into following it

ie, my chargers do what they do, 4.2v i think, then i store

i assume they go down after a few months

wle

I prefer between 3.5 and 3.6, I voted 3.6.

I always do a capacity test on new cells, so they usually get run up to ~4.2V, and I’m too indifferent to run ‘em down to 3.whatever, so…

This question is a regular topic.

Has anyone done any back-of-the-envelope calculations to say economically, what is most logical?

Say, 5 cells of the same kind, stored at 100%, with lower life span Vs 10 cells at 50%.

Cells today are probably better than those 5 years ago, but this is the only study I have seen. They estimated cells stored at 77F for 800 days will degrade, by my estimation of the graphs, as follows- at 3.45v 97.5%, at 3.7v 97%, at 4.1v around 94% of original capacity.

It came from another thread:
:
docware wrote: The study is dated 19.4.2017, cells are Panasonic NCR18650PD. You can read the whole study here :
https://mediatum.ub.tum.de/doc/1355829/file.pdf

See the graphs at the bottom of page 50.

I charge them up to 4.2 volts and store them in my flashlights.

I know that’s not the ideal voltage for maximum longevity, but I’m not concerned about that and prefer to have my flashlights ready to go.

I have several Li-ion batteries that are almost 10 years old and have not noticed an issue with their capacity yet.

My wife has confiscated my ZebraLight SC62w for her EDC and she gives it to me about once a month to charge up the Panasonic NCR18650B since the flashlight is shutting down due to low voltage. It’s around 2.8 volts and charges up to around 3100 mAh. Not bad for an 8 year old battery.

To be prepared for future power outages I store my cells fully charged. I don’t see the purpose of half empty batteries.

I always try to store mine at wall work service between 3.80 and 3.85v, if lower I charge them to around 3.85.
I don’t use storage charge, just normal balance charge and check if all cells don’t deviate too much. If they do I do a storage charge and slowly start thinking/looking for a new.

This is day 944 of a storage test of mine
https://budgetlightforum.com/node/73986
3.8 worked well

I keep mine fully charged. I live in Eastern NC so I have hurricane’s, flood’s, tornado’s, severe thunderstorm’s and during certain year’s we have ice storms to worry about. We have been with out power for weeks at a time before so half charged batteries are a bad idea for me.

it prob won;t make that much difference

plus you will never be able to know anyway! no matter what you do, storage volt wise

wle