I bought my first li-ion light—a ZL SC600cw in April/May of 2012 and I still use it occasionally. I actually carried it for 8 days on a trip through New England one summer and it wasn’t too bulky in shorts.
ETA: The oldest 18650s that I still use are 16 Sony ~2200mAh cells harvested from two ~2004ish VAIO packs and they’re at about 75% and still function at medium to light loads.
They are date coded 2002.
Chris
Trusty vintage 2012 AW 18650 1600mAh still kicking after many moons of use and abuse running my V1 Malkoff Wildcat. I have charged and discharged this old AW 18650 countless times. Oldie but Goodie … 
2014 from a computer battery; still hold a charge.
A few panny A laptop pulls from B’harni knows when.
Sanyo 2400s from KD, Panasonics with the green wrappers, and even a HiMax 2600mAh. All perform good as ever!
So far Flashburn and Chris Garrett are the hands down oldies. Geez. Those things have been around longer even than Boaz.
Well for perspective according to Wiki the first commercially available lithy-ions came from Sony in 1991!!!
Now if sumone still has a working one of those in a flash that wood truly be amazoooooo. :+1:
Eagletac NCR18650A 3100mAh.Have been using since 1.21.2013.Approx. 300 cycles used in a modded TN31 With XPG2.ABOUT 750L/ 500Kcd.
On occassion These batteries can sit a month and are still at 4.15/16 volts 
In terms of age, the closest to those are some NCR18650B 3400mAh (Orbtronic)that are 6 years old.
NOTE: Both of these are still in use…about once a week or so.
Oops! Maybe Jeff51 is der Lithy-King? 
I think this is from around 2008~2009.
6P body bored for 18650
Solar force bezel & stainless insert
Over-ready springless low resistance tail cap mod
Malkoff M60, with USA Cree XRE and Khatod TIR optic. I think Cree XREs were made in North carolina back then. Mine has the white backing, which was characteristic of USA production.
Panasonic 18650 works fine for this application.
Use it all the time as a night stand light. It’s probably around ~175 OTF.
I also have a Zebralight H501 headlamp from about 2009. I just wear it loosely around my neck and point it down to the ground on night hikes. Still use it on backpacking trips where I need to minimize pack weight and volume space. Great camping tent light.
It’s starting to sound like a lotta yooz are holding antique toobs in yer hands along with their complimentary ancient batts.
If ever the SHTF all yer gotta have the latest and greatest will rue throwin out those 22 year old 80% capacity 18650’s.
Old batts rule!!! 
Well I’m keeping mine after reading all this. Was on the fence about tossing them for the new stuff out there butt I’ve changed me mind now.
I’ve got some Trustfire 10440s that must be at least 12 years old. They’re rarely used but are still actually used. I can’t precisely date laptop battery cells but I have Hitachi 17500s from the mid or late 90s that still work for replacing a 3xAAA carrier. Have several green 18650s from a laptop that might have been 15-20 years old.
The oldest light that I use occasionally is the Olight S2 Baton, single protected 18650 and single XML2. Feb. 2016, along with the protected Olight cells that I bought with it. All great with the light and the cells.
Next is Acebeam X65vn spec 1. 8 x 18650, 5 x XHP35. Dec. 2016 and another one March 2017. All great there, along with the cells that came with the lights.
Coming in third is Acebeam X45vn 4 x XHP70.2. 4 x 18650. June 19, 2017. I still use the two sets of unprotected purple Efest cells that I bought with the light.
My lights: https://budgetlightforum.com/t/-/9150/287
My oldest cells are from mid-2014, two Thrunite-rewrapped 18650s bought in a set with an MCC-2 charger. Still work fine, can’t even notice a difference in the charge they hold.
Oh yea… I couldn’t resist when I saw those before I discovered BLF
Old Lumens made a thing of beauty out of his.
I have Samsung 22F laptop pulls from 2009
Well something I’ve wondered about with these old protected 18650’s we’re discussing here is that the PCB’s in them were supposedly only good for around 10 years according to Ultrafire. Quoting right off their blue label……
“PCB life is around 10 years.”
I didn’t use Ultrafire’s ever butt some of the flashes came with them so I have a few 18650’s of them laying about. They’re about 8 years old now so if Ultrafire is giving the PCB 10 years or so of life “theoretically” these protected Ultras should be crapping out in the next three years or so.
Question is outside of Ultrafire’s 18650 are any of your other protected brands (TrustFire, etc) that are now approaching 10 to 20 + years old still have PCB’s that are working fine?
Maybe Ultrafire was FOS (again)?
I have some 2001 to 2003 vintage Sanyo 2100 mah laptop pulls I made into a 5S2P battery for a project. They still happily take a charge. In fact, they’re doing better than some 2016 Samsung 22F’s from another laptop pull for a different project. Otherwise I had some LG’s from I think 2001 (salmon color) that still work but are so worn out only good for low drain. A testament of how good Sanyo batteries are!
I used to let my car battery go until it died. Then one day on a 5 degree F day on New Years day the car did not start and there was no replacement battery to be found anywhere.
After that day, I have changed my battery every five years no matter what the condition of the old one.
What is the lesson here. A battery is a tool that like a knife needs to be sharpened, cleaned and ready to go.
A 12 year old battery is absolutely positively worthless even if it belonged to the chairman of Panasonic himself.
My 18650 efest 3000mah “20amp” from 2015 and 2016.
I also have some battery junction powerizer IMR26650 cells from around 2012. They work fine in my various lights, but I never push them in high current draw applications.