A few years back a local Radio Shack called it quits and offered some really low prices as they closed out. Among the stuff was a number of Eneloops in AA and AAA, for $2 per pack of eight. Needless to say, I made a bit of a hog of myself.
The only concern I had was that they’d been in a hot sunny display window long enough to have faded the packaging somewhat, but I bought them anyway. I’ve used some, but several packs ended up languishing unused in my battery box ever since.
Forward to today. Out of curiosity, I picked up an unopened 8-pack of AAs marked HR-3UTG and dated June 2006. These cells are 12 yrs & 9 mo. old. EVERY SINGLE ONE of this 8-pack tested exactly 1.27 v.
Right now the first four are on my MH-C9000 charger on ‘break in’ mode, all quietly accepting a 0.1C charge and apparently coming up in voltage as evenly as you please. After 22 minutes, they’re all reporting 1.33 v.
I am impressed! I’ll come back to this thread in two days and report where the first four ended up, but so far I can’t get over the fact that they came out of the package almost 13 years old testing as well as they did. They have got to be tough!
The first four of this eight-pack are off the charger, having gone through a break in cycle of something in excess of 38 hours. They terminated sometime during the night, so I’m not exactly sure how long they took.
Late last night before I went to bed they were in the final charge stage, and indicating a nice even 1.38 v.
The charger indicates: 1919 mAh, 1921, 1930, 1930. All terminated at 1.48 v.
The remaining four are on the charger now, also on break-in.
Considering that these cells lay new/dormant for almost 13 years, I wouldn’t have been the least surprised if they’d been deader than John Cleese’ parrot. That they show any life at all, let alone an honest ‘up-to-spec’ capacity is quite remarkable I think.
The last four pieces from that 8-pack finished their break in cycle overnight, and the results (read from the charger) were:
…three of them higher than the first four, with one notably lower.
I noticed one oddity that may be a function of my charger - the first four showed termination at 1.48 v , while these last four all showed 1.44 v when I fetched them off the charger. After 30 minutes all four showed 1.43 v on my DMM. I don’t know exactly how long each set remained on the charger after termination, or if the charger shows the voltage at termination, or ‘at the monent’.
(For those not familiar with the C-9000 charger, break in is a lengthy process of 40ish hours, and both sets terminated sometime during the second night.)
I wish I’d double checked the first four with the DMM after a half hour, but I didn’t.
ChibiM, if you’d like to run some more sophisticated analyses on these old cells, I have a couple of sealed packs remaining that I’d be pleased to send you at no cost.
I have Eneloop AA’s from 2008 that are still in use. They started out life in my camera flash units, taking a beating at weddings. They would come out of the flash unit too hot to hold after literally 700 or more flash photo’s. Nowadays they live an easier life in wireless Mouse units and small flashlights, but they still work fine.
AA Cycler has some very good long-duration cycle tests on Eneloops. Looks like they’re good for about 300-400 full cycles.
After that, internal resistance starts to sky-rocket very quickly. Capacity starts to drop as well, though more slowly. This is my personal anecdotal experience as well, so it’s good to see it’s backed up by real testing.
The conclusion seems to be that after a few hundred cycles, retire them to low-drain applications. If you do partial cycles, you’ll get a lot more out of them.
My personal experience is that they also start to lose their low-self-discharge ability as well, though they’ll still hold a charge for a few months. I have a few worn-out Eneloops that I still use in things like solar lawn lights.
Bravo! Thanks so much for the discharge test Tumbleweed48! Awesome numbers. And keep in mind that overseas cells didnt get charged 100% before shipping out but rather 70-75%.. So yeah, remarkable batteries! See how close those numbers are? Wow... any other brand would have been dead or mismatched numbers. I can't believe they were so close.
If you don't mind, I will add this info to the eneloop101 website.