"This Best Selling Sanyo eneloop SEC-HR4U4BPN 750mAh Minimum, 1500 cycle, 4 Pack AAA, Ni-MH Pre-Charged Rechargeable Batteries Tends to SELL OUT VERY FAST! If this is a MUST HAVE product, be sure to Order Now to avoid disappointment!"
The new SEC-HR4U4BPN 4-AAA eneloop battery pack utilizes SANYO's advanced rechargeable battery technology allowing them to last longer than ever before! They provide excellent performance-to-cost advantages over both conventional alkaline and other rechargeable batteries. Unlike disposable batteries which can only be used only once and are wasteful to the environment, the new eneloop batteries can be recharged up to 1,500 times. They come pre-charged, can be used immediately out of the pack and maintain 75% of their charge for up to 3 years when not in use. Eneloop batteries deliver reliable battery performance when you need it the most!
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:
[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 batteries in the refrigerator to extend their shelf life?
[A] For ordinary NiMH cells, storing them in lower temperature greatly reduces their self-discharge rate so you can get longer shelf life. For eneloop cells it is hardly worth the trouble, because they can be stored for years at room temperature.
[Q15] Can I use eneloop batteries in cordless phones?
[A] Yes – as long as your phones (such as Panasonic DECT 6.0 cordless phones) are using individual AAA cells, instead of battery packs with special connectors.
[Q16] Do rechargeable batteries only go bad after they meet the number of charging cycles, or their lifespan is limited by time also?
[A] Capacity of a NiMH cell gradually deteriorates with number of discharge cycles. The ‘lifespan’ claimed by manufacturer is the number of deep-discharge cycles before capacity drops to 50%. This is done under tightly controlled test conditions, so in real life your result may vary.
[Q17] When rechargeable batteries go bad, do they also spill chemicals (like alkaline cells) or just won’t hold a charge?
[A] Good-quality NiMH cells do not spill electrolyte as they gradually deteriorate. The only chance this can happen is when they are (a) severely over-charged at a high current, or (b) severely over-discharged, or (c) exposed to extreme heat.
[Q18] My baby swing calls for 4 D sized batteries. Do eneloop D spacers work well?
[A] You can use those in a pinch, but expect to replace/recharge your AA cells a lot more frequently than before. This is because the energy stored in an alkaline D cell is about 7-10 times greater than that in eneloop AA cell. See my following review for other options: SANYO Eneloop Spacer Packs with 2 AA with 2 D-Size Spacers
[Q19] My La Crosse BC-700 Battery Charger reports some eneloop batteries as ‘null’. Are they defective?
[A] If a battery is over-discharged and its voltage drops below 0.5V, the La Crosse charger cannot detect it and so the display says ‘null’. Charge your ‘null’ battery in a dumb charger for a few minutes, then the La Crosse charger will recognize it.
[Q20] I read on Wikipedia that there is an Eneloop 3rd generation battery (HR-4UTGB.) Are they worth getting over second generation?
[A] Panasonic (who bought Sanyo in 2009) claims that lifespan of 3rd-gen eneloop cells has been upgraded from 1500 to 1800 cycles. But keep in mind that even if you recharge your cells twice every week, it will take you nearly 15 years to use up 1500 cycles from your 2nd-gen eneloop cells.
[Q21] Are the new AmazonBasics Pre-Charged Rechargeable Batteries just rebranded 1st-gen eneloop cells?
[A] Not exactly. According to their mechanical features, they are most likely SECOND-gen eneloop cells. See my review for details: http://www.amazon.com/review/RLX50IR99K7PL/
[Q22] How do the new Duracell pre-charged Batteries (’2400mAh’, ‘Long Life Ion Core’) compare to Sanyo eneloop or XX cells?
[A] Based on my testing, I believe the Duracell ‘ion core’ AA cells are actually rebranded Sanyo XX AA cells, while the Duracell AAA cells are rebranded 2nd-gen eneloop AAA.
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.
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:
I have tested those new second-generation eneloop cells about one year ago from the Costco eneloop package, and also more recently from the SANYO NEW 1500 eneloop 8 Pack AA. I can honestly say that: while both old and new eneloop are excellent products, their difference in performance is hardly noticeable. Both version have exactly the same capacity rating of ‘Typ 2000mAh, Min 1900mAh’. Actual measured capacity, using my old La Crosse BC-900, is actually about 5% higher at about 2100mAh on the average.
Some advertised improvements of the new eneloop cells looked impressive on paper, but not easy to verify in real life. For example, the new cells claim to have 50% longer lifespan (from 1000 to 1500 cycles). But note that even if you recharge your eneloop cells twice every week, it will take about ten years before you can realize the difference in battery lifespan. The new eneloop also claims to “hold 75% charge after 3 years” in storage, while the old one only claims “80% after two year”. Again, in real life most users will never experience any difference. But then again, it does give a warm and fuzzy feeling knowing that you are getting the latest and greatest rechargeable batteries on the market. (At least until the 2500mAh Sanyo “eneloop-XX” arrives)
Mechanically, there are some very minor differences between original and new eneloop cells (See my upload in the Customer Images section to distinguish between old and new). Note that there are some confusions about ‘vent holes’ on the latest eneloop cells. Some poeple even claim that cells without visible vent holes are counterfeits. But I have tested two batches of new eneloop cells with and without ‘vent holes’, and found them to be identical electrically. So I’m confident that those latest batch I received are genuine.
The Sanyo MQN06 4-cell charger (included in this and many other eneloop packages) is a big let-down. Here’s what I don’t like about this charger:
- It charges in pairs only. This is very inconvenient for appliances that take odd number of cells. If you try to charge an exhausted cell together with a half-full cell, the charging process stops as soon as the second cell is full, which means the first cell is still half-empty.
- The charging current is very low: 300mA for AA cells, 150mA for AAA cells. That means it take about 7 hours to recharge a pair of exhausted eneloop AA cells.
- If you leave a pair of charged cells in an unplugged MQN06, there is a leakage current of 0.5mA. This means a loss of 12mAh per day. In other words, a set of 2000mAh cells will become exhausted in about 5 months. That wipes out the ‘low-self-discharge’ benefit of eneloop cells.
Over the past four years, I have found the original Sanyo eneloop cells to be the most consistent and reliable NiMH cells I have ever used. So I can recommend the new eneloop based on my past experience. On the other hand, I find it inexcusable that Sanyo continues to bundle the best rechargeable batteries with such a mediocre charger. So you may want to consider a package that comes with a better charger, such as the Sony Cycle Energy BCG34HRE4KN, and then buy more Sanyo eneloop cells as needed. This SONY charger can handle each cell individually, and it can be used to recharge any other brands of LSD cells.
I have tested a set of those newest Sanyo eneloop XX Pre-Charged Rechargeable Batteries cells, because they claim to be both pre-charged and have a much higher capacity of ’2500mAh’. Date code on those cells say ’10-08′, which means August 2010. Here are my findings using the La Crosse BC-900 battery charger/analyzer:
- Right out of the package, the average remaining charge was 1004mAh, or just 40% of the rated capacity. The spread is very tight (990-1019mAh), which means they are indeed LSD type. Note that just like the original eneloop, those XX cells were not fully charged when they left factory,
- After just one Charge/Discharge cycle, the average capacity jumped to 2602mAh! Next cycle improved this number slightly to 2607mAH. Again the spread is very small (2570-2650mAh), indicating a good quality control.
Just for comparison, here are some of my test results for other LSD cells:
- SANYO New (1500-cycle) eneloop AA: Rated 2000mAh, tested ~2100mAh (5% higher).
- Rayovac Hybrid AA: Rated 2100mAh, tested ~2100mAh (same).
- GP Recyko NiMH AA: Rated 2100mAh, tested ~2230mAh (6% higher).
- Lenmar R2G AA: Rated 2150mAh, tested ~2030mAh (6% LOWER)
- IMEDION AA: Rated 2400mAh, tested ~2450mAh (2% higher).
- Yuasa Enitime PLUS AA: Rated 2500mAh, tested ~2400mAh (4% LOWER)
Some additional technical details printed on the Sanyo XX package:
- “Typ. 2500mAh, Min. 2400mAh” (The original eneloop claims “Typ. 2000mAh, Min. 1900mAh”)
- “Recharge up to 500 times” (The original eneloop claims 1000 cycles, second-gen eneloop claims 1500 cycles)
- “Retains 75% of the capacity after 1 year of storage at 20 degree C” (The original eneloop claims 85%)
- “Suitable for temperature as low as -20 degree C” (The original eneloop calims -10, second-gen claims -20)
One important note: the Sanyo XX cell is _slightly_ thicker than the orginal eneloop cell. This may prevent you from using the XX in appliances with very tight battery compartments.
In summary, the new Sanyo XX cells really do offer the highest capacity among all LSD cells I have tested. Its capacity is comparable to that of ordinary ‘high-capacity’ NiMH cells, so you get the best of both worlds. On the down-side, it is currently priced about 2x higher than most other LSD cells. So you should only use them for mission-critical applications, where both low self-discharge and high capacity are required.
[Update on Oct 21, 2011]
Long-term self-discharge data:
- One pair of Sanyo XX cells was tested after three months of storage. The average remaining charge is 2060mAh, or 79.2% of their originally measured average capacity (2595mAh)
- Another pair was tested after five months of storage. The average remaining charge is 2040mAh, or 77.9% or their measured capacity (2620mAh). Note that if I use the rated capacity of 2500mAh as base line, then the charge retention rate is 81.6%
Sanyo claims the XX cell can retain 75% of rated capacity after one year of storage. This is consistent with my measured results so far.
Tenergy AA Capacity Battery 1 = 1137 Battery 2 = 1340
Eneloop AA Capacity Battery 1 = 1884 Battery 2 = 1907
Tenergy AAA Capacity Battery 1 = 747 Battery 2 = 752
Eneloop AAA Capacity Battery 1 = 782 Battery 2 = 795
Tenergy AAA batteries actual capacity is 75% (~750/1000 rated) of rated capacity
Eneloop AAA batteries actual capacity is 99% (~790/800 rated) of rated capacity.
The Tenergy AA batteries actual capacity is only 43% (1127/2600 rated) of rated capacity
The Eneloop AA are closer at 95% (~1900/2000 rated) of rated capacity.
Conclusion, spend a few more bucks and get the good (Eneloop) batteries.
** UPDATE 3/21/10 Tested another 4 Tenergy AA batteries, Battery 1 = 1228mah, Battery 2 = 1189mah, Battery 3 = 1193mah and Battery 4 = 1204mah. I’m not sure how they can call these 2600mah batteries.