Life expectancy of a 18650

I still have some of my first 18650 batteries ...

I find they either work ok or they lose their capacity to hold a charge ( cheaper nastier batteries ) for any length of time .

Twice a year I go through my rather large 18650 collection to recharge them all , ( Takes about 3 days ) and its this time I check them for voltage ..

The ones that have lost there charge in 6 months just sitting doing nothing get discarded , but the better quality 18650 hardly lose any charge at all .

I have one panasonic that if left @ 4.2v will still be 4.2v 6 months later .

And other batteries that will be close to 3v after 6 months .. ( See the trend here )

Good batteries will hold a charge , cheap batteries will self discharge , and require more frequent charging ( maintenance )

Im also leaning more towards non protected batteries , as cheap protection circuits might put a slight drain on the battery ( I have noticed this )

Removing the protection circuit stops the battery from self discharging .

If I buy more batteries , they will not be protected .

As for degradation ( ageing ) , this is highly variable and depends very much on initial quality and how much the battery is used .

I store all my 18650 fully charged if they Are garbage in 5 years I don’t care because than we will have better and newer cells which I want anyway…

some of my first 18650s already give up last week,i got them 2010 and been cycled charger 30-35 times a year.
thank you for your services :_(

Lets say your 18650 is 10 Wh (for simplicity)
500 0-100% cycles = 5000 Wh
2000 40-80% cycles = 8000 Wh
It’s not really 4x the lifetime, it’s only 1.6x… with the addition of major inconvenience.

Kodachrome is right, 40-80% is the optimum. One cycle are always 100, no matter if you use 3 times 33.3 or two times 50%.
For example the tesla always charges his battery pack to 80% to enhance his lifetime you need to select the full charge in the cars settings and even than it only lasts for few days until it switches back to 80% max…
But you have to think of the huge amount of cells and the costs in this case, that way different with a dozen cells from a flashlight fan.
—-
I am sure most here recharge the cells before they are empty, I do so, if I recognize a flashlight dimming I recharge this is good for cycle punt and for fun.

Batteries are so cheap so I don’t care so much about this and I always charge them fully because I want maximum current/brightness.

Hmm, it depends what cells you are using. Personally i like high quality batteries which cost like 10$ + per cell, (panas green 3400 protected) and considering i got 2x 4 cell lights, not exactly cheap.

I only have brand batteries but a pair protected panasonics costed me below 14$…so I have bought a dozen or so, I remember times were good batteries were not available or very expensive but it’s a lot better now even ten dollar is okay if you consider to get the best protection circuit and a very good cell…
Sanyo 2600 cost around 11$ per pair…
The lgD1 4.35V batteries are also not so expensive( I ordered 3 pair for 9$ each at fasttech), I recommend them because the higher voltage is a huge benefit especially if you want to use them with linear drivers like the nanjg.
Charging them to only 4.2 gives you the benefit of high cycles with the benefit of high voltage….

I have some lipo RC packs which I store at 3.6V because these are somewhat expensive and I know that I don’t need them fully charged all the time, but even in this case I know that I can toss them in few years…

hallo.i dont want to open new thread…can you reccomend to me any protected 18650 cells-the cheap ones? i need many of them…trustfire flames?
now i need cheap ones,but protected…

You guys must not walk the dog for an hour every night or go hiking, ect.!!!

When I am done my walk, my lights[K40vn,TK75vn, TK61vn, ect.] are around 3.6/3.7v. If I want to keep them at your suggested 3.8v, I would have to shorten my walk[The Siberian would not like that!] or bring another set of batteries w/ me!

I have had my 3400mAh Orbtronic 17 months now, mostly used on turbo, and they still get 52 minutes of max run time compared to 62 when new. My batteries may last 2/3 years but I will get my moneys worth of enjoying them, which to me is not 5 or 10 minutes at a time! Then again, there are people who do that and theirs will last longer.

I see your point but it does not apply to me.

I know it is old thread, but the information is good. Thanks for the advice on this thread, summarisable as keep batteries between 4.1v to 3.8v.

I like the idea of self imposed battery life elongation — a battery charger with that facility — since my current charger is now charging some new-to-me laptop batteries freshly harvested, and does not say that they are charged though they are really bright and charged 4.1 volts. But I need to be able to rely on the little red light turning green, since I don’t want to take out my multimeter all the time, so I may have to chuck these though they seem to work okay (Sony’s from “Fukushima”). Usually they all get up to green after a day of charging. I may look into getting a charger that charges them up less.

I have started a system where I stick a little green sticker on a batter if the battery works well, a yellow sticker if it is flaky and a red sticker if it seems bad. Two red stickers and a batter gets dumped.

I work in a place where quite a lot of laptops get thrown away and I find that the batteries I harvest them are better than ultra-trust-sure-whatever-Fire (which are probably harvested batteries) but since they are unprotected, and I have so many and I some times leave lights on without noticing, I need to throw them away periodically.

They really do explode if you short them

I now keep them in cases in my bag!
But in this video they just get really hot if shorted with a piece of wire

timtak, forget about that “only down to 3.8V” rule. Even considering that being a no-load voltage, it is simply ridiculous. I usually discharge my smartphone battery “all the way down” (which is ≈3.1 - ≈3.5V loaded voltage) and after about close to 2000 usage cycles, I can only discern a small performance difference. Oh! I charge it up to just ≈4V (less than 60% fuel gauge value right now, but they're known to be inaccurate so the actual state of charge is higher).

Samsung's datasheet specifications list a maximum 4V charge voltage for their 35E cells in UPS applications, if this is of service to you.

Cheers :-)

Depth of discharge

Discharge cycles
(NMC / LiPO4)
Table 2: Cycle life as a function of
depth of discharge. A partial discharge reduces stress and prolongs battery life, so does a partial charge. Elevated temperature and high currents also affect cycle life.

Note: 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.
100% DoD ~300 / 600
80% DoD ~400 / 900
60% DoD ~600 / 1,500
40% DoD ~1,500 / 3,000
20% DoD ~1,500 / 9,000
10% DoD ~10,000 / 15,000

what i see looking at this is, you only get so many amp-hours in and out of a cell (until the last line, 10% DoD)
if you discharge 100%, and then charge back up, you get 300-600 of those cycles
50% discharging gives you 2x as many
20% gives you 5x as many
it;s still about the same amount of total energy

which makes it simple
keep it charged when you can
otherwise don;t worry about it

the other thing is, the battery does not just suddenly quit, usually
it gradually loses capacity so that if you don;t notice the top capacity being 75% of what it was new, you can keep going way longer

the numbers are intended to be ‘after X cycles, the battery has only 80% of its new capacity’
but it isn;t dead

wle

[quote=gauss163]

ok then!

(i didnt; think it was all THAT bad though)

wle

Too many variables !
I have had 18650 that only lived a few months , I may still have a 18650 or two that came with my Solarforce L2’s ( Is that like maybe 8 years ago ? or more )
Half my 18650 collection would be close to 5 years old and show no signs of serious degradation ( or noticeable degradation )
I store my 18650 fully charged … ( ? )

Where I see a lot of problems is in the protection circuit … Some have parasitic drain … I had a battery that was always showing 0 volts after 6 months of storage …
I pulled the battery apart , removed the protection circuit and I did not charged that battery in 2 years and it is till showed 4v + …
It looked nasty wrapped in packing tape , and it may have been disposed of in my last battery cull .

If you have a problem battery , it could be the protection circuit . ( If its a protected battery )

> If you have a problem battery , it could be the protection circuit . ( If its a protected battery )

That is what I generally find with cells that stop working. I have ripped the protector off the end to find a good cell still remains.

These days I harvest PC power packs so none of the cells are protected anyway.

This morning I found that a poor 18650 was better than a powerful one since my cheap lights are too powerful in the near field since I keep one of my two bike lights dipped. I keep my better batteries for when I am not facing on-coming traffic on country roads and want throw, to see the critters for instance. But “poor” ones are useful too if they can put out for the one hour of my ride.

Bearing in mind Gaus’ advice, perhaps I should half charge my cells. If so I would need a battery charger that stops at a lower voltage since I don’t have time to hang around checking it. Do such battery chargers exist? What voltage range is equivalent to “50% SOC” and what does “SOC” stand for anyway. Something of Charge.

My Fukushima Sony’s made it to green light 4.1V. There were 6 of them in the pack. I have so many 18650s that perhaps I should just forget about it. At about this time of year folks buy new laptops so there should be 5 more, or up to 30 cells, in the trash soon. I leave a few millimetres of metal strip on the plus end rolled up in a sort of cushion since the only problem with PC batteries is that the plus is flush with the shoulder.

i use a plasma cutter.
adds to the show.

0K gauss163, clear it is to us that you do not seem to be much of a friend of Battery University and/or Cadex. However, many articles there make sense to me and I find them useful. I am not friend of discrediting efforts. I am, however, open to any other additional articles and citations I may find useful too.

There are other relatively inexpensive modules which can be handy to complement with some small power supply and some battery holder(s). Examples:

https://www.banggood.com/Adjustable-5A-LCD-Digital-Step-Down-Power-Supply-6V-32V-to-0-32V-p-1199867.html

https://www.banggood.com/DC-DC-Step-Down-Power-Supply-Adjustable-Module-With-LCD-Display-With-Housing-Case-p-1038740.html

Cheers

Way off topic. Search the forum, there’s threads enough on recommendations, HKJ does good tests. This is plain laziness on your part so I give you a rude point. “I don’t want to open a new thread”. Lazy sod.

BazzH, I recommend you to pay a bit more attention to the posting dates, vresto's request is more than 3 years old.

In AliExpress protected Samsung ICR18650-26F 4-packs can be bought at rock bottom prices if shipping surcharges are not an issue, by the way.

Cheers

LOL, sorry, yer right :smiley: