papershredder
Newly Enlightened
- Joined
- May 31, 2013
- Messages
- 132
We're all familiar with the Eneloop brand 2nd gen (HR-3UTGA) and XX (HR-3UWXA) varieties in the US. They're easy to source here, despite there being slightly newer and better performing varities in other markets, surch as Japan.
The notable differences between these are:
Gen 2 Eneloop
Eneloop XX Gen 2
I'm going to zero in on those cycle counts today. Just what the heck does that mean? 500/1500 before what? Pigs fly?
Well, if you look on the back of the packs the cells come in, they reference IEC61951-2 per the cycle counts.
The exact test that is referenced, section 7.4.1.1 (there are other tests for different types of cells and different tests within the same types) is where they cycle the cell 49 times and check it on the 50th cycle. They're allowed to double check for a 51st cycle the results they got on the 50th cycle. If the conditions are not satisfied, they have to repeat this whole 50(/51) cycle process. The condition to satisfy, essentially, is that the cell is at 60% of its design capacity.
So, to put it in a nutshell, the cycle count means that the cell will only be able to retain 60% of its design capacity after that many cycles. (Keep in mind there are some generalizations being made here. E.g. real world use, temperature swings, etc. The real world is not a laboratory. That being said...)
So, you look at the specs above and you see the 1/3rd cycle count of the XX Eneloop... but, consider:
On the Y axis we have mAh per cycle counts, which is the X axis.
So, you see, that because of the initially higher capacity of the XX cells, despite their more rapid degredation, they don't underperform the gen 2 cells until about 365 cycles.
Numerically, the XX degrades 1.52 mAh per cycle and the gen two; 0.506. Of course there are some assumptions made here (linearity) and generalizations. But, we can be fairly confident where those lines intersect, give or take 50 cycles or so. Work from other individuals lends itself to assumptions of linearity and no hockey stick style responses.
So, my personal conclusions is that the XX cells are still good for my applications. I only need to recharge a few times a week, meaning I'll get years and years of above-gen-2-performance out of the cells. I think the same can be said of most people.
Eneloops are good. =)
The notable differences between these are:
Gen 2 Eneloop
- 75% capacity retained after 3 years.
- 1900 minimum mAh.
- 1500 cycles.
- $$
Eneloop XX Gen 2
- 75% capacity retained after 1 year.
- 2400 minimum mAh.
- 500 cycles.
- $$$
I'm going to zero in on those cycle counts today. Just what the heck does that mean? 500/1500 before what? Pigs fly?
Well, if you look on the back of the packs the cells come in, they reference IEC61951-2 per the cycle counts.
The exact test that is referenced, section 7.4.1.1 (there are other tests for different types of cells and different tests within the same types) is where they cycle the cell 49 times and check it on the 50th cycle. They're allowed to double check for a 51st cycle the results they got on the 50th cycle. If the conditions are not satisfied, they have to repeat this whole 50(/51) cycle process. The condition to satisfy, essentially, is that the cell is at 60% of its design capacity.
So, to put it in a nutshell, the cycle count means that the cell will only be able to retain 60% of its design capacity after that many cycles. (Keep in mind there are some generalizations being made here. E.g. real world use, temperature swings, etc. The real world is not a laboratory. That being said...)
So, you look at the specs above and you see the 1/3rd cycle count of the XX Eneloop... but, consider:
On the Y axis we have mAh per cycle counts, which is the X axis.
So, you see, that because of the initially higher capacity of the XX cells, despite their more rapid degredation, they don't underperform the gen 2 cells until about 365 cycles.
Numerically, the XX degrades 1.52 mAh per cycle and the gen two; 0.506. Of course there are some assumptions made here (linearity) and generalizations. But, we can be fairly confident where those lines intersect, give or take 50 cycles or so. Work from other individuals lends itself to assumptions of linearity and no hockey stick style responses.
So, my personal conclusions is that the XX cells are still good for my applications. I only need to recharge a few times a week, meaning I'll get years and years of above-gen-2-performance out of the cells. I think the same can be said of most people.
Eneloops are good. =)
Last edited: