Eneloop vs Hybrid 30 and 60 day Self-Discharge Study

wasBlinded

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I've done a 30 day comparison with two Sanyo Eneloop 2000 mAh AA cells and two Ray-O-Vac Hybrid 2100 mAh AA cells. I know this is a very small sample and I apologize for that, but at least its something. I am also editing this post to add the 60 day results on another set of four cells.

Each cell was run through the "Forming Charge" routine on the Maha C-9000, and the initial mAh ratings were taken from those runs. This entails a C/10 charge for 16 hours and a C/5 discharge. They were then stored at about 60 deg F for 30 days and 61 days until put through a discharge test at 400 mA to give the following results:

Eneloop Eneloop Hybrid Hybrid

Initial mAh 1951 1938 2040 2050

30day mAh 1802 1800 1830 1825

Capac. Loss 7.6% 7.1% 10.3% 10.9%

Eneloop Eneloop Hybrid Hybrid

Initial mAh 1935 1955 2039 2039

61day mAh 1767 1789 1807 1803

Capac. Loss 8.7% 8.5% 11.4% 11.6%


The Hybrids started off with a bit more capacity, lost more of their capacity in the first month, but still ended up with a higher capacity at the end of 30 and 60 days. It is interesting to note that both Hybrid and Eneloop cells in this test seemed to lose only a little more than another 1% of their capacity in the second 30 day period (if the two batches can be considered to behave the same).

Just for some more data, the first four cells were then put through the C-9000 "Refresh-Analyze" program, with a 1000 mA charge followed by a 400 mA discharge, and the cells (same order) gave the following mAh capacities:

1928 1925 2004 2021

So the standard C/2 charge does not lose you too much total capacity compared to the forming charge on the C-9000
 
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Re: Eneloop vs Hybrid 30 day Self-Discharge Study

Thanks for test. I am glad to see that the Hybrids are holding their own against the Eneloops, since I bought 40 of them with my ten $5 off coupons.
 
Re: Eneloop vs Hybrid 30 day Self-Discharge Study

please do post as soon as you run the 60 day test. I will remember to look for it on Feb 30th (ooops, no such date!)
 
Re: Eneloop vs Hybrid 30 day Self-Discharge Study

I'll edit and add to the first message of this thread when I complete the 60 day test, and give it a bump.
 
Re: Eneloop vs Hybrid 30 day Self-Discharge Study

I thought that I had read somewhere that you do not have to do a forming charge on the Eneloop cells? I have the same Maha charger so I could do one if it helps....is it recommended? Thanks!
 
Re: Eneloop vs Hybrid 30 day Self-Discharge Study

I don't know if it does or does not help to do a forming charge on Eneloops or Hybrids, but it won't hurt. It is one way to be sure the cell is given as much charge as it can possibly take, and it is the standard method of determining a cell's capacity, as used by the manufacturers.
 
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