I received 3 KeepPower 5200 cells today. One will be “in use”, the others will ultimately go into storage at 50% charge. OR should I just check the voltage on those cells and just store them if they’re where they should be? I really wanted to check their capacities, but if they are better left uncharged, that’s OK.
Doing a C-D-C cycle won’t affect the cell for storage if you charge it back to the original voltage, which is the optimal charge state for storage determined by the factory.
Once I kept NCR-B for more than two years and they were still healthy as new.
Thanks. Maybe I’m weird, but I want to know that I received what I thought I was buying. I’ve gotten burned with Chinese counterfeits in the past, but I don’t expect banggood to do that. But I still believe in “trust but verify”.
I live in a high fire and earthquake area and keep four sets of batteries for each utility flashlight (four of them) fully charged and ready for service.
I check every six months for charge and a load test; I also now check impedance. I am more concerned with ‘need’ and not the number of ‘recycles’.
That’s a smart thing to do sidecross, sounds like a California locale. I think I’d also keep important papers and such in a strongbox ready to ditty’, and probably a go bag always packed with enough for a few days to a week (and lots of purified water or the ability to make my own with a Katadyn or some such). I think I’d do much the same if I lived in the Pacific northwest if I was on the coast and the Cascadia fault was a danger. One might need to get to high ground with not much time to do it.
I use a flashlight every night, and a few times every night most nights. Right now I have an L6 that I charge every few weeks as needed, and a C8 for the wife, that might need charging every 6 months during the long days. That might change as the days shorten. But I want a one battery L2 available also, though I don’t know why. Maybe just because I can. I like the small size and the reach. Time will tell if I actually use it and I might wind up rethinking my idea of having a charged battery in the L2. For me the biggest problem on my horizon are my so called “leaders”. I can make our own juice, but I want to make sure that I have batteries enough just in case they screw things up big time. But I know that they would never do that (written with tongue firmly planted in cheek).
Personally, I just leave them at 4.2V. It adds a small amount of wear versus storing at 3.7V, but I figure I’ll probably upgrade my cells long before they wear out. This way I know I always have full batteries if I need a spare and I don’t have to keep track of which ones are charged / not charged.
If you really want to keep them best for long-term storage, 40% charge is optimal. Spitballing, that’s like 3.3V or so. Given my druthers, I’d also want my chargers to cut off at 3.7V-3.8V (~90%), not 4.2V. But that’s just me…
Cells you intend to use or keep as emergency cells, go’head and charge them fully. You’ll probably lose some capacity stuffing them to the gills all the time, but probably not so much as to be noticeable.
I’ve got a few usb-input chargers, so I can charge my 18650s from an outlet, in a car, from a computer, whatever has a powered usb port. Of all the cells I’ve got, I only keep like 3-4 in constant rotation. A ’501 MOP, ’502 SMO, C8 w/ XP-E2 (nice thrower!), and defunct ’98 (now in a ’501 UV).
All the rest, I (dis)charged to 40%(ish) and they’re tucked away nice’n’warm.
According to HKJ 3.8v gives you about 60% rather than 90%. To get the latter amount the battery would have to be charged to over 4v. You can see his results here
The link was 404 for me, but thanks for the correction!
Think I was remembering the cc/cv cutover on the charging algorithm, only thing I can guess why I was stuck on that 3.7V figure. Just got it into my head that fresh from the charger would be 4.2V, dropping rather quickly to the nominal 3.7V.
Ah, wait… LFP cells (LiFePO4)! Yeah, see
for the curve I was thinking of (hope I did the link right).
(And which explains why I’m using an LFP cell in my now-1xAA Quark. )
Thanks! The advanced post editor worked much better!
Edit: BTW, one of the 3 cells that I got in yesterday tested out at a fantastic 5495maH capacity (labeled as 5200) in the Opus. So I’m using that one in the one cell L2. The others are fairly close in capacity so I’m considering those to be “paired” if I need to use them that way.
Similar to an EV, Li-ion in satellites must also endure a lifespan of 8 years and more. To achieve this, the cells are charged to only 3.90V/cell and lower. An interesting discovery was made by NASA in that Li-ion dwelling above 4.10V/cell tend to decompose due to electrolyte oxidation on the cathode, while those charged to lower voltages lose capacity due to the SEI buildup on the anode.
NASA reports that once Li-ion passes the 8 year mark after having delivered about 40,000 cycles in a satellite, cell deterioration caused by this phenomenon progresses quickly. Charging to 3.92V/cell appears to provide the best compromise in term of maximum longevity, but this reduces the capacity to only about 60 percent.
Cool! The “satellites” link was seamlessly copy/pasted on the advanced editor. :THUMBS-UP:
I have been using it consistently for a long time now. The emoticons of the simple one also work on it, in case you didn't know. 8^)