Hi. A couple of months ago I saw some AAA Ni-MH cells made by GS Yuasa. Since most of the sites you usually recommend to get eneloops or any kind of batteries are in the US and shipping costs make buying from them a bit expensive to me, I got a pack of four enitimes just to try them.
Since my C9000 was busy doing break-ins I used a couple of them in a remote, but I think the drain can be said negligible. The cells are advertised as 750 mAh
Surprisingly the readings were more stable than expected. The only worry was the lower capacity under higher discharge rate. Then I did a Break-in (Since I couldnt use 750 to specify the capacity I used 700)
Since nobody seems to have them or made some kind of test I decided to do one.
Some days after the break-in I did several charge/discharge cycles to try to find a more trustable capacity. After every charge I left the cells in the charger to top off. Here are the C9000 readings:
Charge #1: 759 mAh
Discharge #1: 745 mAh
Charge #2: 751 mAh
Discharge #2: 745 mAh
Charge #3: 746 mAh
Then I stored the cell (and another 3 more) in a drawer. No special care here
A month later I did a discharge on that cell and got 676 mAh. About 90.7 % of the initial charge. After that, I did again a charge (+ top off again) and discharge to check if the todal capacity changed.
Charge 1 - 764 mAh
Discharge 1 - 751 mAh
Charge 2 - 732 mAh
I stored it again and will check next month to see if 90% is a reliable number. I have another 3 cells charged and untouched to get the remaining capacity at 3, 6 and 12 months (unless I need them before).
I discharged again the same cell and got 661 mAh. Las time I charged it, the C9000 put 732 mAh in and then I left the battery there a couple of hours more to Topp-off. Since, according to previous discharges, the capacity is about 745 mAh, then the loss is almost 12% in only one month .
That's not good for an LSD battery: should be 15% / 20% in a whole year. Next month I will discharge a different one, trying to figure out the self discharge after 3 months.
The second cell on the pack I bought was charged (+ Top Off) and discharged a several times to get the real capacity. Last two discharges showed 761 and 768 mAh. Then I charged it again (again, topping off). Three months later (yesterday) I did a discharge and got 633 mAh, which is 0.82 of the initial charge, so it lost 18% in 3 months.
Originally Posted by Mr Happy
Also the self-discharge is much more rapid at the beginning. It should slow down after the first month or two.
The 'shallow charge' tends to bleed off first, but the 'deep charge' holds more strongly.
I think Mr Happy nailed it. I was expecting somewhat worse due one-month only test, but according to the new result they seem to be a cheap alternative for a decent LSD battery for those of us who cant get AAA eneloops for less than 10 euro (pack of 4). I can get these for about 6€ right now. Not bad, indeed.
I will charge & discharge this second battery a couple of times again to check the capacity and will do a 1-month discharge test on this one too.
EDIT: After a new charge & discharge the capacity was 756 mAh.
Almost forgot to check another cell after 6 months.
This time the results are:
Original capacity: 756 mAh
After 6 ˝ months: 579 mAh
That is 76.6% of the original capacity or a 23.4% loss in that time. A bit worse than the 80% Black Rose said, but I think it's not that bad (and if you take in account the half additional month it "should" be a bit better, maybe 77% or so in the 6 month mark).
After discharging the battery I did a charge & discharge test (500/200 mA) to check if there was any visible loss in capacity for being idle that much time. The result was 760 mAh. No need to worry a lot cycling them every few months to keem them in shape, it seems.
After 12 months and a half y did a discharge in the last cell left.
The original capacity were 758 mAh and one year (and a bit) later the discharge showed 530 mAh. Putting that in percentage, the cell retains around 70% of the original charge. Not in the eneloop level, but not bad either.
The good thing about it is that the self discharge slowed-down A LOT after the 6 months mark: only about 7% in the last 6 months. Of course the test is only one sample and you should take the results with a grain of salt.
When I bought these cells, they were the cheapest LSD I could find. Nowadays they are cheaper alternatives (and I can find cheaper eneloops too) and at that price they are not worht much...
Yes, thanks so much for doing this... I purchased a pack of these batteries in the past month, they seem to work well, but until now, the only way I'd know if they were good after a year was to sit on my hind end and wait to see....
Now I know! While the Eneloops are claimed to be better, this "real world test by a mortal human with no skin in the game" proves they are capable enough, and worth the money they cost. So, for no other reason, I shall be ordering more!
One more data point -- I bought a pack of four Enitime AA cells a year ago, measured their capacity, and recharged. They've been sitting at room temperature (a bit warmer in the summer) for one year, and I just discharged them. The remaining charge was 78% of the capacity I measured before storing them.
Since I got LOTS of LSD AAA (The everfast) and had too many alkies that came with new things, the enitime are still unused (maybe a burst of a couple of seconds in a E01 with one of the cells, IIRC). Next month I will be able to test the LSD capabilities after 2 years
I was unable to discharge a cell yesterday. Doing it now a 200mA.
The 1st cell I discharged showed 322 mAh after 25 months (~2 years). Before putting it to rest the capacity I got was 756 mAh, so the remaining is only 42.6 %.
I found it a bit too low, so discharged another cell. This one is a month "older" (26), and got 331. Since this cell is 751 mAh, the remaining is 43.8%.
LSD tend to slow down the self discharge with age. We saw it with eneloops and the behaviour of these yuasa over the first year. Then we get a LOT of self discharge the second year (compared with what it should be). Two things can be happened here:
- The LSD capabilities of these cells fade a bit after a year.
- I (or someone) used the cells. Yes, it can be this one. Since I didn't plan to do such a long test, using them is not out of the question.
I don't plan to do again a 2 year long test just to discard I used those cells, sorry. I have 2 more cells and will try to remember to discharge them when they get 2 years since las charge. Using the 4 of them is HIGHLY unlikely.
I bought recently several Enitime since i was satisfied with them after more than 1 year use in Logitech equipement.
But i was disappointed. The cells had only 40% of their initial charge left when i discharged them after arrival.
I tested all in all about 20 AA/AAA. All had less than 50% of their 800/2000 mAh capacity. I sent the lot of 160 cells back and ordered eneloops instead since i had not the time and equipement to prepare 160 cells before first use.