[wprebay kw=”lower+cost” num=”10″ ebcat=”-1″] [wprebay kw=”lower+cost” num=”11″ ebcat=”-1″]
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.
BOTTOM LINE: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.
Just in case you are looking for my “Sanyo eneloop FAQ”, it can now be found here:http://www.amazon.com/review/R9VPVQ0UO2MKH
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This package (Sanyo SEC-HR4U4BPN) contains four second-generation eneloop AAA rechargeable batteries. I have tested those cells using my old La Crosse BC-900 Advanced Battery Charger. Here are my findings:- Right out of the package, the average remaining charge is 640mAh, or 80% of the rated capacity (800mAh)- After the first recharge cycle, the average capacity increased to 839mAh.- After two more recharge/discharge cycles, the average capacity leveled off at 843mAh, or 5% higher than rated capacity.
The above is very consistent with the results I obtained last year, while testing 2nd-gen eneloop AAA cells from the Costco package. Therefore I have no doubt that those batteries are genuine. Date code embossed on them says “10-12″, which means Dec 2010 (see my upload in the “Customer Images” section, if you need to know where to find the date code).
According to Sanyo press releases, those 2nd-generation eneloop cells offer several benefits over the original eneloop:- Can be recharged “up to 1500 cycles” (vs. “1000 cycles” for the original)- Can hold “75% charge after 3 years” (vs. “80% after 2 years”)- Works down to -20 degree C (vs. -10 degree C)
In real life, however, it is nearly impossible for the average user to experience those benefits. Note the even if you recharge your cells twice every week, it will take nearly ten years to reach 1000 cycles. Furthermore, the advertised self-discharge rates for new and old eneloop cells are actually the same during first two years.
As to the capacity: original eneloop AAA cells have “Typ. 800mAh, Min. 750mAh” printed on them. The new eneloop AAA cells only say “Min. 750mAh”. This has created confusions for some people, who thought the new version has lower capacity. But according to Sanyo web site, capacity of the new AAA is also 800mAh typical. My own test results, however, have shown that measured capacity of the original eneloop is around 4% higher than rated, whereas capacity of the new eneloop is about 5% higher than rated. Again, the difference is so small that most users will never notice it.
BOTTOM LINE:Second-generation eneloop cells do offer some improvements over the original, but the actual benefit is very hard to verify in real life. In my case, the price I paid for this new eneloop AAA package is only 10% higher than that of the old one, so I consider it a good deal. If the price difference is much greater, then you have to decide whether it is worthwhile to pay extra for those perceived benefits.
[Update on May 31, 2011]Prices for the new eneloop AAA have came down further during the past month, so now it is an even better deal. But just in case you are looking for greater bargains, you may want to consider the GP ReCkyo Pre-Charged AAA cells. They are priced lower than Sanyo eneloop, and have slightly higher capacity (rated 850mAh, measured 880mAh).
[Update on July 31, 2011]Long term self-discharge data: I have tested a pair of new eneloop AAA cells after 92 days sitting on the shelf (the batteries, not me). The average remaining charge is 89.4%. 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 July 3, 2012]Amazon again combined multiple Sanyo eneloop products (many AA/AAA packages and different chargers) into a single product page. This makes it very difficult for people to find reviews for a specific product. In particular, my “Sanyo eneloop FAQ” was previously attached to the product page of Sanyo eneloop 4 Pack AA, but now it can only be found by following this link:http://www.amazon.com/review/R9VPVQ0UO2MKH
I have been using Sanyo eneloop low-self-discharge NiMH batteries since beginning of 2007, and I’m completely satisfied with them. One thing I noticed is that newcomers to the rechargeable battery arena often have similar questions/confusions about eneloop. So here is my list of eneloop Frequently Asked Questions. This list is work in progress.
[Q1] My Sanyo eneloop AA batteries say ‘1900mAh’ on them. Are they counterfeits?[A] All eneloop AA cells (both original and second-gen versions) are rated for “Typ 2000mAh, Min 1900mAh” according to Sanyo. The confusing part is that 2nd-gen eneloop AA cell only has “Min 1900mAh” printed on it, even though the actual measured capacity is close to 2100mAh.Simialrily, eneloop AAA cells are rated for “Typ 800mAh, Min 750mAh”.
[Q2] Date code on my new eneloop cells says ’10 01′ (Jan 2010). Should I exchange them for newer batteries?[A] Relax! Unlike ordinary NiMH cells, Sanyo eneloop are still perfectly good even after 5 years in storage. Once you recharge them, they will return to 100% capacity again.
[Q3] What is the difference between ‘Pre-Charged’, ‘Hybrid’, ‘Stay-Charged’, ‘Active Charged’, ‘Ready to Use’ and ‘Ready to Go’?[A] Those are all marketing terms for Low-Self-Discharge (LSD) NiMH batteries. Sanyo first used the term ‘Pre-Charged’ for Sanyo eneloop back in 2006. Rayovac used ‘Hybrid’, and so on.
[Q4] I just received some new eneloop batteries. Do I need to recharge them before use?[A] You can use them right out of the package. However, eneloop cells are only charge up to ~75% when they left factory. So you can use a Smart charger to ‘top-off’ their charges. Do NOT do this with a Dumb charger because it will badly over-charge them.
[Q5] I thought I have to drain my batteries completely before recharging them?[A] This is only necessary if you are using a timer-based dumb charger. With a smart charger, you can top-off your batteries anytime.
[Q6] Can I use other brands of chargers to recharge Sanyo eneloop batteries?[A] Sanyo eneloop batteries can be recharged using any good-quality Smart charger designed for NiMH cells. But for longer battery lifespan, avoid ultra-fast (15- or 30-minute) chargers and Dumb (overnight) slow chargers
[Q7] What is the difference between ‘Smart’ and ‘Dumb’ chargers?[A] A Smart charger monitors the voltage profile of each cell individually during charging, and stops when a charge-termination signal (negative delta-Voltage) is detected. This is the only way to avoid over-charging. A Dumb charge relies on safety timer to stop charging, or has no termination mechanism at all. This usually results in over-charging which is bad for battery lifespan.
[Q8] Should I stick to the Sanyo MQN06 charger packaged with most Sanyo packages?[A] The MQN06 is semi-smart but has two issues: it charges in pairs (monitors the combined voltage of two cells), and the charging current is only 300mA. That means it take about 7 hour to recharge a pair of eneloop AA cells. A better choice is the Sony Cycle Energy BCG34HLD.[ Note: Charge time (hour) = Capacity (mAh) / Current (mA) ]
[Q9] What is the best charging speed for Sanyo eneloop?[A] Choose a charger that gives you charge time between 2-5 hours. That means charging current of 500-1000mA for AA, 200-500mA for AAA.
[Q10] Isn’t it true the best charging speed for NiMH and LSD-NiMH battery is the slowest?[A] That is only true when using a dumb charger which blindly charges for 12-15 hours, so the current has to be below 0.1C (200mA for a 2000mAh cell) to avoid over-heating. For a smart charger, the current needs to be at least 0.2C to ensure proper termination.
[Q11] I always keep a set of ordinary NiMH batteries in the charger to keep them freshly charged. So why do I need LSD cells?[A] You don’t need to do that with LSD cells. Just charge up a spare set ahead of time and keep them in your drawer. Swap them in whenever needed, just as how you use disposable cells.
[Q12] Why should I buy those 2000mAh Sanyo eneloop instead of ordinary NiMH batteries that are rated 2500mAh or higher?[A] All rechargeable NiMH AA cells rated 2500mAh or higher are susceptible to Rapid-self-discharge problem. Beware of off-brand batteries that claim ‘2900mAh’ or higher. Most of them can’t even deliver 2000mAh.
[Q13] Can I use eneloop in places with extremely hot weather?[A] As a rule of thumb, every 10 degree C rise in temperature causes the battery’s self-discharge rate to double. So although your eneloop cells can still function correctly, their shelf life will be reduced at high ambient temperature.
[Q14] Should I store unused eneloop…