Panasonic BK-3MCCA4BA eneloop AA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries, 4 Pack

(10 customer reviews)

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Recharge up to 2100 times

Maintain up to 70% of their charge after 10 years (when not it use)

2000mAh type, 1900mAh min, Ni-MH pre-charged rechargeable battery

Pre-Charged at the factory using solar power and ready to use

No memory effect – batteries can be recharged when fully, or partially discharged

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Brand: Panasonic


Panasonic BK-3MCCA4BA eneloop AA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries, 4 Pack

Additional information


Product Dimensions

0.6 x 3.38 x 4.25 inches

Item Weight

0.256 ounces

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Item can be shipped within U.S.

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Item model number



4 AA batteries required. (included)

Is Discontinued By Manufacturer


Date First Available

April 11, 2014





Country of Origin


10 reviews for Panasonic BK-3MCCA4BA eneloop AA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries, 4 Pack

  1. NLee the Engineer

    I have done extensive study on low-self-discharge (or ‘pre-charged’) rechargeable batteries, starting from early 2007 when the  original Sanyo eneloop cells  were introduced to the US market. Subsequently I have tested  Sanyo 2nd-gen eneloop , followed by  Sanyo 3rd-gen eneloop  and finally these  Panasonic 4th-gen eneloop .Every single eneloop cell I have purchased in the past 8 years, including the original ones, are still in good working conditions. That says a lot about the quality of eneloop batteries. But the question is: are there any REAL improvements in later generations of eneloop batteries?[Capacity]The advertised capacity ratings for all eneloop (1st to 4th-gen) batteries are identical:- AA cells are rated “Typ. 2,000mAh, Min. 1,900mAh”- AAA cells are rated “Typ. 800mAh, Min. 750mAh”Actual capacity measurement, using my old  La Crosse BC-900 Battery Charger , also showed that capacity numbers are consistent from 1st to 4th-gen. In fact, my measured results are consistently about 4-5% higher than the advertised values.[Charge Retention Rate]With each new generation, eneloop’s long-term charge retention rate gets a little more ambitious:- 1st-gen claims “85% after 1 year”- 2nd-gen claims “85% after 1 year; 75% after 3 years”- 3rd-gen claims “90% after 1 year; 80% after 3 years; 70% after 5 years”- 4th-gen claims “90% after 1 year; 70% after 5 years”Notice that those numbers are essential the same, just extending over longer period of time. In fact, I have tested a set of first-gen eneloop cells after 3.5 years in storage, and they still contain around 75% of rated capacity. To me, this shows that there are no real changes in the charge retention rate among different generations.[Cycle Life]The main difference between different generations is in the advertised lifespan:- 1st-gen: ‘1000 cyles’- 2nd-gen: ‘1500 cycles’- 3rd-gen: ‘1800 cycles’- 4th-gen: ‘2100 cycles’Let’s consider how long it takes to actually test a rechargeable battery through 2100 deep discharge/recharge cycles:The standard test procedure calls for charging at 0.2C (~5 hours) and discharging at 0.2C (~5 hours), plus cooling period of one hour each between charge and discharge phases. So a complete cycle takes about 12 hours. To exercise a battery through 2100 cycles would therefore take nearly three years!However, 3rd and 4th-gen eneloop cells are both released less than 2 years from their previous generations.[Bottom Line]My theory is that all eneloop 2nd/3rd/4th gen batteries are in fact made with the same battery technology. It takes many years to collect the actual cycle life and charge-retention rate data. Therefore only later generations are able to advertise higher number of cycles and longer storage life.If my theory is true, then it follows that there’s no reason to pay higher price to get the latest 4th-gen eneloop. Any earlier generation of eneloop would perform just as well.Finally, if you are extremely ‘value conscious’ like me, consider the following rebranded eneloop batteries and get the same quality for even less:-  AmazonBasics Pre-Charged Rechargeable Batteries  (in white wrappers) are rebranded Sanyo eneloop.-  AmazonBasics High-Capacity Pre-Charged Rechargeable Batteries  (in black wrappers) are rebranded  SANYO eneloop XX batteries –  Duracell Ion Core AA Rechargeable Batteries  are rebranded Sanyo XX, while  Duracell Ion Core AAA cells  are rebranded eneloop AAA batteries[Update on Dec 22, 2015]For additional information on eneloop batteries in general, please refer to my newly updated “Panasonic/Sanyo eneloop FAQ”:

  2. Kevin R

    Who doesn’t like eneloops. I had some from 2009 in my Bug Out Bag which still held a charge. Well worth the little bit of extra money compared to cheaper alkaline batteries. They also won’t leak their toxic guts like alkaline batteries sometimes do. They seem to work better in the cold (not compared to L91/92) than alkaline batteries and preform better in higher draw electronics such as today’s flashlights.

  3. Tony

    I have ordered and used dozens of the batteries and I am extremely pleased with these batteries.In reality, beyond a few hundred recharge cycles how do you check the 2,100 recharge claim? I instead focus on the number of recharge failures per 1000 hours of recharging. I have 20+ of these batteries and I’ve recharged each around 20+ times without a failure. Each battery seems to last for many weeks, even months, after each recharge. I use a number of them for safety lights with motion detectors embedded in the lights and the batteries last 3-4 weeks. For recharges or service life time I have not even come close to any observable failures but, realistically, during 400 charging events I have a very a low probability of seeing one poor recharge or charge failure even.I have not seen any noticeable reduction in times between charges but so far, given my many weeks between charges, I would not expect this issue to manifest itself.One last observation. Given a time between charges of 2-3 weeks or longer it is impossible to actually see a single battery fail. 2,100 cycles at 2 weeks/charge event results in a single battery failure of a minimum of 4,200 weeks or 80+ years or so between failures, an unreasonable time frame for testing.The earlier 1500 charges and now the 2,100 charges, all seem to be a marketing ploy that may, or may not, be rooted in what the average consumer really needs, you decide if even 1,000 hours pays for itself compared to the alternatives! 🙂


    I can’t say enough good things about this battery. I use a tens unit 24/7 and this battery lasts longer then any other battery I have used. Instead of having to change my batteries every two days these last four days. Purchase the charger that goes with and you can charge your batteries in three hours instead of twelve hours. The batteries pay for themselves with a few uses. I am never going back to regular “leaky” batteries again.

  5. demonsRendangered

    I got my first set of eneloop batteries back in 2012 which was 9 years ago. I’m impressed with how long they’ve held out since I use them constantly for things like my Wii remotes, led statues, wireless mouse/keyboard, etc. They’ve gone through so many charges and to be honest I thought they would’ve given out years ago but they ended up lasting much longer than I anticipated. A pair of them finally stopped holding a charge so I decided to pick up some more. This will be the brand I always look for. Top notch brand and to be clear my first pair I purchased on Amazon as well so it seems certain that they stock good batteries.

  6. RyGoSt

    Nothing to find fault with. Assuming you have an external battery charger from the likes of nitecore you never have to but batteries again. They recharge up to sum 2100 times and do. So quickly enough. Good power output. Though out even for digital and hi end applications. Get on the band wagon, recharge and don’t rebuy. Serious technology to save your wallet and the planet not to. Mention the superior craftmanship.

  7. Big Bear

    I have been buying rechargeable batteries since the late 70s. I’ll tell you some things. Get a high quality charger. (I am using a 15 year old maha C 401fs. It now costs $44. A cheap charger will beat up your batteries and make your investment worthless. Look for individually controlled charging slots, – delta-v, temperature monitoring. I like to charge AA and AAA batteries at 500 ma. Slow charging means your batteries take more charging cycles.I see a “top review” that alleges these are “fraud batteries” because unused they drop to 1.3 volts. the opinion expressed in that review should carry little weight. It’s important to remember that NIMH batteries might be chargeable to 1.5 volts but that is just “surface charge” and it will disappear with the smallest use or time. NIMH technology is rated at 1.2 volts. When you take a battery off charge and measure it immediately the voltage you are picking up the “surface charge” effect; that is the reason you can ever get a 1.5 volt measurement off nimh batteries but that’s just “Surface charge” it does not represent useable power. Don’t believe me? Then it’s time to learn more about battery charging. I’d suggest your favorite search engine.If you use rechargeables the way I do you will spend a lot more than $4. a year on batteries so a good quality charger makes sense. 1. Candlepower forums does not sell batteries or chargers, but the folks there publish the best reviews, including technical details. 2. Eneloops whites are simply the longest lasting batteries available. Low self discharge (aka pre-charged nimh, aka LSD batteries should hold an 85% charge through a year of storage in reasonable conditions and these do. I have used them all from Eneloops to tenergy centuras to the old (no longer available) Harbor freight precharged to duracell precharged. I am lucky if any other brand takes half as many charges as eneloops. I use a 4 AAA moderately high discharge flashlight about 10 hours a week for work and that’s a couple of charge cycles. Also my Oral B, and a grooming appliance are powered by AA’s, along with the usual complement of low drainitems where I might use a lesser NIMH battery. I do think the price is high, but I buy white eneloops for high-use systems because they last. The black eneloops store more power but do self-discharge a bit more, and do not take as many cycles. Bottom line: bite the bullet on price, go quality and enjoy reliable, economical, low environmental burden batteries; Japanese eneloop whites are the best of breed.

  8. GC0110

    I’ve kept track of my rechargeable batteries over the years, and have gone thru various brands, name brand and ‘brand x’.’ The Eneloops are the clear winner, having lasted 8-10 years before they finally gave up. The others were good for 3-6 years on average. I also like that the Eneloops don’t try to cram a tiny more power into them by making the battery case slightly larger, and then not fitting so easily in my devices. The difference in mAh is too little to care about, and I like that the Eneloops fit just fine without trying to cram them into a space that’s a tad too small. They also keep their charge well as to being almost near top capacity even a few months after they were last charged and have sat unused. So, I’m sticking with them as my go-to battery company.

  9. Bill

    My wife was buying a bulk pack of batteries for remotes, xbox controls, and several other AA battery items in the house. It takes 2 to 3 days to drain two AA Duracell batteries in an xbox controller. Rechargeable AA’s charge to 1.2 volts unlike regular non rechargeable batteries which charge to 1.5. So the life is slightly shorter when used but I’ve been using the last set I bought for several years with no issues. They seem to last longer than a few other rechargeable brands I’ve bought in the past. Keep a few charged in a drawer for backups and just change out you need to.

  10. Boheeber

    Well, as of this writing there are only 3,542 other reviews, but I may as well add mine. These batteries are the stuff, as we say. I use them in my digital camera (yes, some people still use them), and in my Terralux flashlight. The only way to get maximum brightness from the flashlight is to use this type of battery, and as far as the camera is concerned, it just makes good financial sense to use these rechargeables. The money saved over buying alkaline or regular AA batteries is reason enough to buy these. They arrive precharged, but I have already had to recharge them in my Sony BCG-34HRMF charger, and it doesn’t take long at all to get them up to a full charge. You cannot go wrong with these batteries.Addendum 3/26/2017: Just received 16 more of these and they are now coming from the factory with a notation indicating the initial charge is done with solar energy. One more cool thing about these.

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