Charge retention - 18650 vs LSD AA vs lithium primaries

The projected use is emergency lanterns, the kind that tend to get stashed and neglected until needed. Used to use the old 12v style. Generally batteries would go dead before discharged. Replacing those is a modestly expensive pain and the lanterns by today’s standards are quite large. OTOH, something too small would likely migrate away, so a small 18650 tail stand light is not as desirable for this purpose. I can always go get one of those should the need arise.

I personally put my 18650 at storage voltage, then stash them in the fridge in airtight containers. But, should I charge them up to say ~4.0v how long would the charge last at a decent level, maybe better than 40%? A year, 2 years, more?
Something like a LSD Eneloop could be used but would require charging. Yearly would be good. I think every 2 years might be pushing it.
Lithium primaries (AA), would likely go the longest but are maybe the most expensive option.

I’m thinking a light possibly like this. 30 LED Collapsible Lantern
But I’m open to suggestions, not too big, not too small.

I don’t know which rechargeable option would last the longest. The Lithium Primaries would surely beat them both, but are single use only. Thus, rechargeables would beat primaries in total longevity, obviously.

Yeah, that part I figured. Part of the decision is long term cost vs. convenience+neglect. That part I need to decide. I’m hoping to fill in the rechargeable part of the equation better to make that decision.

I’m sorry but I don’t really understand the post. are you asking about lanterns or batteries?
I would go personally go for 18650’s and charge them al the way up. I’m living off-grid though so I cycle them regulary. But for me 18650 cells are cheaper then lithium primaries bought locally. I believe I paid 5euro for an CR123 lithium and just recently paid about4euro for an 3000maH 18650. So even if I don’t store them at the recommended voltage they turn out way cheaper.
I would not go for Nimh LSD cells as I think they don’t hold enough energy to be used in lantern that burns for quite some time .
Maybe you should ask yourself how frequently the need arises to use the lantern/batteries and how long will you need to use everytime. I’m guessing you’ll use it for power outage, so you could probably check on the internet to find out how many power outages there where in the last years and how long it took to get the power going again. Then try to figure out how many cells you’ll need to get through the outage and keep them charged up full or near full charge.

This is about which batteries are most suitable in lanterns for long term storage and occasional use.
Unlike you these would not necessarily be cycled regularly. That’s a variable and a decision that needs to be made.
If a rechargeable 18650 can go 2+ years just sitting and still have more than 50-75% of it’s charge it could be a decent option. I don’t know if they will do that. I’ve never used them that way so don’t have any experience.

Ah ok, well there is a test going on on the forum but it’s about 18350 cells I believe. I think the question was asked by djozz to other members to see how long their efest cells hold their charge. A lot of people jumped in and charged different cells to put away and then checked (regulary?) to see how they are doing. Maybe we could set something up like that for 18650’s. I think we would see a difference between high capacity cells, high discharge cells and protected cells.

Edit: If they have to sit for 2years or more and it’s just for light in emergencies: get some candles, keep em dry and they’ll keep their charge for ever :smiley:

Found the thread:
charge retention imr

And I found this video back that I watched a few weeks ago, should be of interest for you

I have two of that lantern exactly. And they don’t work well with nihm. Eneliops pros Duracell’s imedion etc. They are bright at first then fall off rather quickly. When used with alkaline it works much better. I’ve tried over and over again. Usually its the other way aroubdm like in a ea41 or tn4a eneloop pros blow it away. But in this case lithium primaries are your best option for this lantern. Also these are very cheaply. Made don’t ve surprised in 3-4 of the LEDs go out.

The video was pretty interesting.
I suspect that age, history, and particular type of cell would make a difference, maybe a big difference.
I’m not sure the efest thread is too useful. Sounds like those may just be poor cells. I have a lot of history with NiMh and cell quality makes a huge difference in reliability and longevity.

Yeah I mentioned the thread more as an idea, I’m willing to put a cell or 2 apart for a year or so to do the test if/when more are willing todo the same so we can get some comparison going on.

Keep in mind 18650 start out holding much more energy than 2xCR123 for example. So if it depletes to 50% of its capacity, the remaining performance is still decent.

Of course, you need a light that functions properly on a 1/2 drained 18650. Likely, for an emergency light the reduced brightness is probably OK.

Also, the fridge might keep the battery from set-discharging but it’s pretty bad to freeze lithium-ions, at least let them warm up before use if you aren’t sure exactly how cold your fridge is.

One of the issues is how long can you keep a 18650 charged and stored and get decent performance from it? It’s a very long experiment and one I certainly have not done.

Similarly, there is a general consensus not to freeze Lion. I’m not sure that’s true. I’m doing my own experiment. I have a new cell, tested, then I’ve been storing it @3.7v in the freezer at around 0*F. About once a month I pull it out and run it through a cycle with Lii-500. 6 months in and I haven’t seen physical damage or capacity loss.
BatteryUniversity does seem to indicate that storage at freezing is OK.

How far below that is not referenced. I kind of think once you get to freezing there’s some flexibility below that. In the big picture I’m not sure of the benefit below just a cold fridge.