I have been using them since 2005, back then i had started with Rayovac Hybrid, worked great but lost their low self discharge and seemed to sag a lot then eventually (10 years maybe) started to leak at the head I have since recycled all of them.
I have also used some Duracell NiMH, not Eneloops, did great for years, one is now defective (self discharges like crazy), i just did a drain test on a couple more yesterday, having trouble recharging them, as soon as i put them on the charger they jump from 0.9 to 1.28V then read charged a few mins later. Took some cycling but are now charging again.
I also have some green wrap Ikea Ladda, also not Eneloop rebadges, so far so good, 2017 issue.
Then onto the Eneloops.
I have a few packs in circulation, no problems so far, they are probably from 2010-2015. And i have some newer ones that are still in the package, not sure from when, a couple years before covid i imagine.
So i am curious, is 10 years the expected lifetime?
If not cycled as well?
Or if lightly cycled?
In another thread, I mention that it depends. I have opened/tested two sealed 8-packs of 5th Anniversary Eneloop Glitters after 38 months and they’re still almost as perfect as Eneloop/Fujitsu/FDK batteries can be.
I only buy standard capacity ‘Eneloop’ (LSD) batteries now, as opposed the higher capacity versions, which seem to die a hard death between 2-4 years.
I have NiMh AA cells inside the microscopes that I use in the school where work, they power the inbuild led illumination. They are charged every now and then by connecting a mains plug. The circuitry inside the microscopes does not have low voltage protection, while the pupils often put the microscopes back in the cupboard with the light still switched on. It is desastrous for the batteries to be drained to death all the time, I have to replace the rotten batteries every three years. I bet if a simple LVP was build in, they had never needed replacing.
Interesting you mention this, i left the Duracell cells on for a couple hours past dead accidentally and one registered zero volts, the other 0.6V.
I left them overnight and today registered 1.??V but then did the weird stuff i mentioned above.
They never used to, i could drain them and they didn’t blink, but that was years ago.
NIMH is certainly more resilient than Lithium when drained to 0v.
I wouldn’t be too concerned about it unless you want max life.
For max life, the newest gen Eneloops/Fujitsu batteries (non pro). They actually have a “lite” version that has much lower capacity but even longer cycle life.
A decade is normal for Eneloops unless you cycle them every day, even then, they are rated for 2100 cycles (4th gen) and if you cycled them everyday, that’s 5.7 years.
quote from post:
“Total cumulative capacity for the Chinese Eneloop is now about 2,400 Ah - equivalent to about 1,200 full cycles. The Japanese Eneloop has now done a total of about 4,700 Ah - equivalent to 2,350 full cycles - significantly more than the advertised rating of 2,100 cycles (which is measured with only partial discharges, so this goes well beyond the official rating, and it still isn’t dead yet!) I suspect that this is the most cycled Eneloop ever…”
granted he did “partial” cycles (over 5000!), but he did an equivalent of 2,350 full cycles and still had about 64% of the initial capacity on the high discharge graph (worst case). So it does help to have some sort of LVP.
There are tests that have been done with unused still sealed in package 10 year old Eneloops, not even charged before testing, where they still had 60% of original stated capacity.
That’s an absolutely amazing low self discharge rate, and I’m sure if you charged it, it would have 90% of the original capacity. 10 years is a long time and not much will last longer than that. The only unknown is if those 10 year old eneloops will still get their “2100 cycle” rating.
The only thing that comes to mind is energizers throw away lithiums.
I don’t care if they are down to zero in 10 years after only being charged at the factory, i mean in 10 years can i use them like new batteries or are they going to lose their LSD ability, voltage sag, cut out, display charging anomalies and so forth.
I do have some older unused eneloops, i’ll have to check how old.
Is there a way to date them?
I have some that date from 2013, i have two packs that have never seen a charger or been used.
they should have a date embossed on them, sometimes you have to get the light reflected off of it just right to read it
first two numbers are year and second two are month.
the ones I have are “20-09”
IMO, there is still no consumer NiMH that will outlast the standard Eneloop in longevity.
I have several AA Eneloops I purchased around 1994 when they first showed up at Costco. I haven’t tested their capacity but they still work fine in AA lights and remotes, etc. I also have at least 100 Eneloops/Duraloops that are well over a decade old. All my other AA/AAA NiMH cells have failed within 5 years, including non-standard model Eneloops. Of roughly 150 standard Eneloops in rotation, Ive discarded less than 10 since 1994, which were all AAA. None of my AA standard Eneloops have ever failed, at least that I am aware of.
Capacity tests reduce the life of Eneloops and require no “refresh” gimmicks to maintain them. I do however, recharge them using ONLY high quality chargers (Powerex MH-C9000) @800 mAh, which are the only chargers I use for all my NiMH cells. I never recharge/top-off partially charged cells, always nearly depleted ones.
Clean power delivery from a quality charger plugged into a conditioned mains supply, never allowing a deep discharge or overcharge, proper and consistent charge ramp and end of charge termination, heat management and proper charge current are also key to long cell life. Most of my name brand lithium cells also survive well past what most others get out of them. All it takes is one slip-up and the cell life will be reduced.
In general, Ive found that cheep cells cost several times more than high quality cells throughout the life of the cell.
Totally agree, all my non-Eneloop/Fujitsu LSD batteries died over the years but only 1 or 2 Eneloops failed. If I remember correctly MH-C9000 uses different termination method than most other chargers so it is the best NiMh charger.
When you said that you always charge nearly depleted NiMhs - do you (should I) discharge them before charging them? In many case these discharged NiMhs still show 1.2v or close when I put them in C9000? Also you should charge NiMhs @0.5-1C to ensure the correct termination, 800 mAh seems too low for AAs and a little high for AAAs.
I recently charged up some NiMH batteries that had been dead for 13 years. Out of about 15 cells only 2 wouldn’t recharge to max voltage, those 2 were dead. Honestly couldn’t believe it, I have some powering AA lights and working great. These were Energizer brand.
I did a lot of research before settling on the C9000’s and read from others recommending 1000 mAh to assure consistent termination. If I remember correctly, the charger monitors cell temperatures as one of the criteria to determine if the cell has been mostly charged, then enters a trickle charge phase for a predetermined time to top-off the cell before terminating. In my experience the 1000 mAh charge rate for correct termination is only true with the early versions of that charger. The latest firmware and power supply seems to have corrected the problem. The cells ran rather warm @1000 mAh charge rate (especially on stations 2 & 3). Ive found that charging at 800 mAh keeps the cells a lot cooler and also provides more consistent resting voltages from cell to cell (measured 2 days after recharging). After recharging, I keep my cells grouped by mfgr date and sorted by resting voltage. If using cells in high current series devices (flashlights, etc), I always check and compare ending voltages to make sure I dont have a failing cell in my rotation. Very seldom does a cell miss a termination, and I monitor the chargers when they are in use while working at my desk.
1.2V after the cell has rested is a depleted cell. You can damage them by over-discharging. I generally dont replace cells unless they are depleted. But yes, I do discharge them if necessary before recharging. Very low discharge devices or ones with parasitic drain can run cells dead, so be careful… if that matters to you.
I recharge AAA’s @300 mAh.
I should also add that I had 4 x C9000’s that terminated inconsistently. I called the manufacturer and they exchanged them for new ones with the latest firmware. I noticed the power supply was different on the new version, so not sure if that may have influenced reliability. At that time, I also replaced a UPS with an expensive commercial unit (through work) to supply my sensitive devices, so another variable in the mix.
All in all, a great charger solution when combined with standard Eneloops.
