2,783 of 2,832 people found the following review helpful
Those are genuine second-generation eneloop cells - as far as I can tell,
This review is from: eneloop AA 1800 cycle, Ni-MH Pre-Charged Rechargeable Batteries, 8 Pack (Electronics)
I have done extensive testing on the original eneloop rechargeable batteries since early 2007, shortly after they were introduced in the US. I have also tested the blue second-generation eneloop cells from the Costco eneloop package back in 2010. But this is the first time I have seen second-gen eneloop in white wrappings being sold in the US. With so much talk about counterfeit eneloop going around, I was understandably cautious when I purchased those SANYO NEW 1500 eneloop 8 Pack AA Ni-MH Pre-Charged Rechargeable Batteries.
I tested four of those cells, using my old La Crosse BC-900 Battery Charger.
- Right out of the package, their average remaining charge is 1568mAh, or nearly 80% of the rated capacity of 2000mAh. The spread is also very small, from 1558 to 1577mAh. This proves that they are indeed low-self-discharge type. (Date code on my cells says "11-01", or Jan 2011)
- After one recharge/discharge cycle, their average capacity improved to 2115mAh
- After two more recharge/discharge cycles, their average capacity leveled off at 2133mAh, or more than 6% higher than the rated capacity.
The above results are very consistent with what I have previously observed, while testing second-gen eneloop cells in the Costco package. Therefore I'm convinced that those are indeed genuine second-gen Sanyo eneloop cells. (See the scans I uploaded to Customer Images section, if you need to distinguish between old and new eneloop cells)
On the other hand, currently the prices of those new eneloop cells are about 25-50% higher than that of the original eneloop cells. So one may question: do the new eneloop cells offer sufficient improvement over the old, to justify the price different? Let's compare the following factors:
- Cycle Life: The 2nd-gen eneloop claims to "recharge up to 1500 cycles", while the original only claims 1000 cycles. This 50% improvement looks great on paper, but note that if you recharge your eneloop cells twice every week, it will take 10 years to reach 1000 cycles. So in real life, most average users will never notice the difference.
- Self-Discharge Rate: The new eneloop cells claim to "maintain 75% charge after 3 years", while the original only claims "80% after 2 years". Again, in real life most people will never notice the difference.
- Capacity: First-gen eneloop AA cells have "Typ 2000mAh, Min 1900mAh" printed on them, while 2nd-gen eneloop AA cells only say "Min 1900mAh". But in fact they have the same capacity rating of 2000mAh (typical) according to official Sanyo web site. My measured capacity numbers are actually around 2100mAh for both versions.
Both the new and old eneloop cells are excellent products. You can safely mix and match them in any application, and probably nobody can tell the difference in the next 10 years. But in case you can't decide which version is a better value... Just flip a coin and pick one - you can't lose either way!
[Update on July 31, 2011]
Long term self-discharge data: I have tested a pair of new eneloop AA cells after 104 days sitting on the shelf (the batteries, not me). The average remaining charge is 88.7%. This charge-retention rate is slightly better than that of the original eneloop, but the difference is within margin of error for my experiment.
[Update on May 8, 2012]
Nowadays the 2nd-gen eneloop cells are generally priced lower than the original. So you should definitely get the newer version.
[Update on Apr 7, 2013]
Long-term self-discharge rate update: I just tested a set of 2nd-gen eneloop AA cells after two years in storage. They retained 1685mAh, or 84% of rated capacity. This is no difference from the claimed charge retention rate of 3rd-gen enellop (which says 85% after two years). See my following review on 3rd-gen eneloop:
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Showing 1-10 of 277 posts in this discussion
Initial post: Apr 21, 2011 9:18:24 AM PDT
J. Golton says:
Thanks NLee for validating these as 2nd generation (2g). I think the most valuable thing about the 2g Eneloops is that they take only one round of discharge/recharge to get to (approximately) full capacity. A person will typically recharge a battery for only one round after purchase and will not go online to find out the need for multiple discharge/recharge cycles. So this version is much more plug and play for the masses, and that will be worth the higher price for some.
I'm the guy who gave a mildly negative review for Duracell Pre Charged Rechargeable NiMH AA Batteries, 4-Pack which has occupied the top slot for negative reviews. I really like the concept behind Eneloop and their copycats. With my one issue addressed, I wholeheartedly endorse the Eneloop 2G batteries as the best AA batteries available.
Posted on Apr 22, 2011 5:39:13 AM PDT
D. Doyle says:
Great review N!
(I can't imagine how the 4 reviewers who are ranked higher than you got there :)
Posted on Apr 22, 2011 8:50:37 AM PDT
Last edited by the author on Apr 22, 2011 8:55:20 AM PDT
I believe one other advantage of the 2nd gen Eneloops is that they perform better in lower temperatures which is probably the most important difference, at least to me. I use them in a wireless temperature sensor which is mounted outside, also keep them in flashlights in the car, so this improvement if it's confirmed would be very useful (in winter time).
Old -10 deg C
New -20 deg C
In reply to an earlier post on Apr 23, 2011 8:26:14 AM PDT
Last edited by the author on Apr 23, 2011 8:27:10 AM PDT
The improved low-temperature rating is again a 'feel-good' factor, but it is hard to quantify the benefit in real life.
All NiMH cells suffer from reduced capacity when operating at below freezing. But the change is gradual. For example, the old eneloop may suffer 20% drop at -10 deg C, while the new eneloop may suffer 20% drop at -20 deg C. It does not mean that the old eneloop will drop dead at -20 deg C. I have used old Sanyo eneloop and Rayovac Hybrid in my outdoor temperature transmitter, and they performed just fine over the past 4 winters, where night time temperature may drop to around 0 deg F (-17 deg C).
Not that I want to discourage you from buying the 2nd-gen eneloop cell (they are still better than the 1st-gen version). But you should know the real benefits if you have to pay extra for them.
Posted on Apr 25, 2011 4:14:44 AM PDT
Pine Nut says:
Can these batteries be charged with any NI-MH charger such as Sony BCG-34HUE?
In reply to an earlier post on Apr 25, 2011 6:20:36 AM PDT
As a general rule, Sanyo eneloop (or other brands of Pre-Charged cells) can be recharged using good quality, 'smart' charger designed for NiMH cells. For the sake of battery lifespan, pick one that charges in 2-5 hours (I'm not familrar with Sony BCG-34HUE, but I assume it falls into this class). Avoid over-night chargers and '15-minute' chargers.
In reply to an earlier post on Apr 30, 2011 6:23:37 AM PDT
NLee, have you ever compared the weights of the various batteries? Shouldn't their respective masses reflect their capacities, all other factors being equal--which is probably not the case. Nonetheless, it's easy to do and might be interesting to see if there is a correlation.
In reply to an earlier post on Apr 30, 2011 11:46:21 PM PDT
Last edited by the author on Apr 30, 2011 11:49:28 PM PDT
I don't have a precision scale at home, so I can only rely on the weight specifications published by manufacturers. Here are some data points:
- SONY 'lite' AA (1000mAh): 18g
- Sanyo eneloop AA (2000mAh): 27g
- Rayovac Hybrid AA (2100mAh): 28g
- Kodak NiMH AA (2600mAh): 28g
- Energizer NiMH AA (2500mAh): 30g
So there is some correlation between weight and capacity, but it is not 100% reliable. In general, heavier cell just means it has a fatter casing, which implies there is more 'stuff' in it.
In reply to an earlier post on May 2, 2011 8:15:06 AM PDT
S. Sen says:
"Avoid over-night chargers and '15-minute' chargers"
I wonder why so? I have been using the overnight charger that came with the Eneloop batteries and my first set of batteries bought in 2008 still works great. I use them in my Wii remote and don't need to charge more than twice a week even after 3 years.
In reply to an earlier post on May 2, 2011 9:36:47 AM PDT
Last edited by the author on May 2, 2011 9:47:26 AM PDT
The Sanyo 4-position Battery Charger MQN06 that came with eneloop package is not an overnight charger. It actually monitors the voltage profile of each pair of cells during charging, and it terminates charging as soon as one of them is full.
An 'overnight' charger typically charges at a low current (such as 200mA) and never terminate. It is up to the user to remove the cells after 12-16 hours of charging, or else cells will be over-charged. One such exmaple is the Rayovac Easy Charger.
Other 'overnight' chargers may have a built-in timer that stops charging after 8 hours. For example: the Rayovac Platinum Universal Battery Charger. This is slightly better, but it can still lead to over-charging if the capacity of the cell is lower than expected, or if the cells were not fully drained before charging.
On the other hand, a '15-minute' chargers uses a huge charging current of 8-10 Amps. This will heat up the batteries rapidly during charging, which then lead to reduced lifespan.