Best AA Batteries and Chargers: 2016 Update

Fujitsu Charger and 3 batteries
1 AAA and 2 AAA batteries in Fujitsu’s excellent budget charger

Over the past 5 years, I’ve written many articles about pre-charged, low self-discharge AA and AAA rechargeable NiMH batteries. Such batteries, used in conjunction with a high quality charger, offer consumers the best combination of quality, durability, environmental sustainability, and cost-effectiveness, as compared with other types of rechargeable batteries or single-use Alkaline batteries. I explained why in my original AA battery article, and more briefly review below.

This article has been replaced with a 2018 AA Batteries update, due to various changes and other developments in the AA/AAA batteries category.

In this post I update everything for 2016. I will also update this post with any significant developments for at least 11 additional months.

This year’s post is the longest yet, so use the following section links if you want to skip around:


Introductory Remarks

Poor quality is rampant among rechargeable battery and charger brands, causing many consumers to give up on rechargeable batteries. Sifting through thousands of potential items to find the good stuff takes time. I’ve done that, through a combination of personal testing, speaking with industry professionals, examining tests from other battery enthusiasts, and just enthusiastically learning everything I can about AA and AAA batteries over the past 5 years. Changes happen slowly in this category, so an update once every year or two is about right.

For years I have tried to keep battery advice simple by emphasizing the Eneloop brand, which could always be counted on to have the highest quality low self-discharge rechargeable NiMH batteries. I still recommend low self-discharge batteries over all others for general purpose AA and AAA battery use.

However, my recommendations this year are not so Eneloop-centric, because . . .

The highest quality low self-discharge rechargeable NiMH batteries ship from a factory in Takasaki, Japan. To date, this level of quality has not been duplicated elsewhere.

Starting in mid-2014, Panasonic began shipping China-sourced Eneloops to Australia and some markets in Asia. Low self-discharge batteries sourced from China cost less but have inferior quality to batteries sourced from the Takasaki factory in every respect.

There have been no reports to date of China-sourced Eneloops sold through reputable retailers in North America, Europe, or Japan. However, Eneloops purchased through e-bay or third-party merchants could potentially be sourced from anywhere.

Previously, I referred to batteries which matched Eneloop quality as “rebranded Eneloops.” This was not strictly accurate . . . they are Takasaki-sourced batteries. Sanyo did own both the Eneloop brand and the Takasaki factory through 2009. However, since December 2009, Fujitsu’s FDK subsidiary has owned the Takasaki factory, while Panasonic has owned the Eneloop brand. It is this factory which produces the highest quality low self-discharge batteries in the world, and this is where all Eneloops were produced prior to 2014.

It was fair to say that no other brand produced superior low self-discharge NiMH batteries to Eneloop through 2014. With Panasonic now sourcing some Eneloops from China, it’s no longer that simple.

Given that these batteries last for decades, I recommend purchasing only the highest quality low self-discharge rechargeable batteries. How can you do this? By making sure they come from the Takasaki factory, as follows (in order of greatest to least assurance of quality):

  1. Buy Fujitsu-branded low self-discharge batteries. Given that Fujitsu owns the Takasaki factory, they have every incentive to use it for their own batteries.
  2. Buy Eneloops from reputable retailers in North America, Europe or Japan, who sell Eneloops which are “Made in Japan.” In the U.S., reputable retailers of Eneloop include Amazon (but not necessarily third-party merchants on Amazon), NewEgg, and Costco. There are surely others but I’m certain about these three. There are other brands besides Eneloop which source from the Takasaki factory, but some of them do not clearly label where batteries come from. Genuine Eneloop batteries have historically always been labeled clearly and accurately.
  3. Buy Amazon Basics low self-discharge batteries. They are from the Takasaki plant and appear to match 2nd generation Eneloops when tested. They are not as good as the currently shipping 4th/5th generations, but they are less expensive and work reasonable well.
  4. You can take a chance on some other brand or merchant. When you receive the batteries, carefully read the packaging, including the fine print on the batteries themselves, to be certain they are from Japan. This will work most of the time, though there have been occasional reports of batteries which falsely claim “Produced in Japan.”

For more details about the history of Sanyo, Eneloop, Panasonic, Fujitsu, and the factory in Takasaki, Japan, skip to the Takasaki section of this article.

Just Tell Me What to Buy

Some publications like to give you that one single best thing to buy. I typically don’t, as I attempt to match product to desired specifications and price points. But . . . if you don’t already own a good charger or any low self-discharge batteries, the following bundle is a great way to get started at a very reasonable cost:

Panasonic KJ17MCC82A Eneloop Power Pack for 8AA, 2AAA, 2 C Spacers, 2 D Spacers, Advanced Individual Battery Charger

If you have a good charger and just want to buy batteries, then you can’t go wrong with Fujitsu, which owns the Takasaki factory that makes the best low self-discharge batteries in the world:

Fujitsu Ready-to-use 8 AA rechargeable NiMH batteries HR3UTC 2000mAh

Fujitsu Ready-to-use 8 AAA rechargeable NiMH batteries HR4UTC 800mAh

For a slightly more nuanced “best battery summary recommendation, just scroll up a few lines to read your four choices for buying high quality, low self-discharge rechargeable batteries.

The rest of this article explains relevant features, describes quality differences between different brands, and recommends a number of other models and brands depending on features of interest and budget.

Why Low Self-discharge AA NiMH Batteries Beat Other Types of Batteries

For a thorough explanation of different battery chemistries, read Best AA Batteries You Never Heard of. This section provides a short recap:

The two broad classifications of AA or AAA batteries are single use and rechargeable. Single-use batteries must be disposed of after a single use, while rechargeable batteries can be recharged hundreds of times using a battery charger suitable for AA or AAA batteries.

Single-use batteries have been produced from a number of different battery chemistries over the last few decades. The two most popular chemistries for single-use batteries in recent years are Alkaline and Lithium.

Alkaline batteries continue to be very popular due to low cost, convenience, slightly higher voltage, and longevity (amount of time before first use). Alkaline batteries can be obtained for as little as 25 cents each when purchased in 48-packs. However the low cost of Alkaline batteries is not so low when you consider that they can only be used once.

Consider a digital camera that uses 4 AA batteries. Perhaps it runs through 12 sets of 4 batteries per year. That comes out to 48 batteries per year which can be purchased in bulk for $11.50. The Eneloop alternative is to purchase a battery/charger pack that includes 4 low self-discharge rechargeable AA batteries and a charger for $18 or so. The latest Eneloops can be recharged up to 2100 times, which means that they’ll last over a century. The total cost will include approximately 10 cents/year in electricity costs, so the total costs over a century of use will be $28.00 for the Eneloops, versus $1,150.00 for the Alkaline batteries. You won’t live for a century, but even after two years the Eneloops cost less at $18.20 versus $23.00.

Actually, I was being generous to Alkaline batteries, by assuming they last as long as Eneloops in a digital camera. They don’t. Alkaline batteries drain much faster in high drain devices than NiMH or Lithium. If you have Alkaline batteries that you want to use for something, use them in low-drain devices such as remote controls for TVs or game consoles to get the most out of them.

For the majority of applications, low self-discharge batteries perform the same or better than Alkaline batteries, at a lower cost over time. However, some devices assume the 1.5V starting voltage of Alkaline batteries. Such devices may not function properly or even at all with 1.2V NiMH batteries inserted. For such devices, Alkaline or Lithium batteries must be used.

I personally avoid devices that require 1.5V AA batteries. Not only do they prevent me from using low self-discharge rechargeable batteries, but such devices quit working after only 1/3 of the Alkaline battery’s stored energy is used. This is because Alkaline battery voltage decreases with use, typically falling below 1.2V with only one third of the stored energy depleted.

Lithium batteries don’t suffer from either high drain or low voltage issues. So for those rare devices that require high voltage, lithium batteries are ideal. They could also be used on a long trip to power a high drain device (i.e. digital camera) when there is no access to electricity for recharging. However, lithium batteries are by far the most expensive type of battery and can only be used once, so you’ll want to keep their use to a minimum.

Rechargeable batteries come in many different chemistries, but over the past decade NiMH (Nickel Metal Hydride) is by far the most efficient, cost-effective and popular chemistry for use in AA or AAA batteries. There are two broad classifications of NiMH rechargeable batteries: high self-discharge, and low self-discharge.

High self-discharge NiMH AA batteries have been around for two decades. Improvements to early versions quickly led to NiMH with high capacity and low internal resistance, which made them the most popular alternative for rechargeable AA or AAA batteries. They were recommended for use in high-drain devices and many people used them that way.

However, two issues led to dissatisfaction, which caused many consumers to give up on them and return to using less expensive Alkaline batteries:

  • Low quality chargers bundled with these batteries often led to poor user experiences with batteries being undercharged (therefore not lasting as long) or overcharged (thus deteriorating in quality over the course of months instead of years).
  • When not being used, such NiMH batteries discharge at a very high rate. After 4-6 months of non-use, they are essentially dead. This makes them poorly suited for use in devices that are only used occasionally.

I do not recommend high self-discharge NiMH batteries for any use, because of the much superior kind of NiMH battery that has been available since 2005:

Low self-discharge NiMH batteries, first invented and popularized by Sanyo’s Eneloop brand, are now by far the best option for most applications requiring AA or AAA batteries. Unlike high self-discharge batteries, the rate of discharge is low, with 85% of charge retained after a year of non-use, and 70% after 5 years of non-use. Such batteries are typically labeled “pre-charged” or “ready-to-use”, because they retain their charge after leaving the factory. But that is a minor benefit compared to the low self-discharge rate. This type of battery also typically lasts for over 1000 recharges, as compared with 500 at most for the high self-discharge variety, and sometimes much less. The superior low self-discharge variety is more expensive, but most definitely worth it, lasting decades with no drawbacks.

A low self-discharge battery paired with a poor charger can still lead to a poor user experience. But there are several great chargers on the market, which I discuss later in this post. Before doing that, here’s some more detail on the different generations of low self-discharge batteries.

Low Self-discharge Batteries Since 2005: Generations 1-5

Flashlight and camera enthusiasts are so excited about low self-discharge batteries that they have tested and documented many aspects of the technology on various sites, especially CandlePowerForums. I love this chart about the different Eneloop generations. A more accurate and updated version of this chart has been created by the same author on his eneloop101 site: Complete Eneloop Lineup (click at the top for PDF chart).

It is clear from the chart that the biggest improvements occurred by 2010. In 2009, second generation Eneloops increased battery lifetime from 1000 to 1500 recharges while also discharging at a lower rate. A high capacity version came out in 2010, labeled XX at first but now called the Eneloop Pro.

Since 2010, improvements have been very gradual, so marketing claims have shifted slowly. I’m not even sure that the so-called 5th generation Eneloop is any different than the 4th generation . . .

I interviewed a Fujitsu employee familiar with the Takasaki factory. He requested not to be identified. While he was not at liberty to supply me with as much detail as I would have liked, I did ascertain that there are numerous small process and technology improvements that occur gradually over time at this factory. A change in the marketing claims listed on the package of Eneloops or other low self-discharge NiMH battery brands does not represent a discreet, brand new generation of the technology. Rather, it represents gradual change accumulated over several years, enough to warrant a change in marketing claims.

The implication of gradual process improvement is that a set of batteries purchased months before a packaging change might not be significantly different from the batteries purchased after the packaging change. But there likely are significant differences between batteries which are produced years apart, after years of accumulated improvements.

It’s unclear to me that there is any difference between regular capacity 5th generation Eneloops and 4th generation Eneloops. The marketing claims changed, but they don’t contradict each other. The 4th generation cells claimed 70% capacity after 5 years, while 5th generation claims 70% capacity after 10 years or 90% after 1 year, depending on the packaging. These claims are all consistent with each other—it could be that after 5 years the cells lose capacity very slowly. Furthermore, the manufacturing codes on the batteries are the same as well, lending support to my theory that this type of battery has changed very little over the past year, possibly not at all.

When I asked my contact at Fujitsu whether there really was a 5th generation, he said that there has been no recent significant breakthrough and there are none about to come out (at least that he was willing to tell me). He reiterated that process improvements happen frequently but very gradually. Changing claims is simply a marketing call. Fujitsu has not changed claims for its own brand of low self-discharge battery cells and has no imminent plans to do so.

So far as I was able to ascertain, it doesn’t matter who claims what. 4th or 5th generation batteries coming out of the Takasaki factory right now are all of similar high quality, whether it’s Eneloop, Fujitsu, or some other brand (though note that capacity and longevity differ, depending on specifications). And they are probably very similar to batteries that shipped out of Takasaki a few months prior, though perhaps very slight improvement may have occurred.

Several battery enthusiasts do claim, however, that budget-priced Amazon Basics low self-discharge batteries are 2nd generation, based on how they test out. The performance of 6-year-old 2nd generation low self-discharge NiMH batteries definitely lags currently shipping batteries, as you can see from this Eneloop generations chart (click at the top for PDF chart).

It does appear as though there have been some improvements over time to the high capacity versions (which Panasonic calls Eneloop Pro, and Fujitsu calls High Capacity). Panasonic now claims a slightly higher minimum capacity for both AA and AAA high-capacity batteries, as shown on page 17 (or page 9 by PDF numbering) of the current European version of the Eneloop catalog.

Recommended Low Self-discharge AA Battery Brands

So which brands are good to buy? First of all, make sure you’re getting low self-discharge NiMH batteries. They typically say the words, “pre-charged” or “ready-to-use” or “low self-discharge” on the packaging or as part of the online product description. NiMH will also be in the description.

Once you’re sure they are low self-discharge NiMH batteries, pay attention to the words, “Made in Japan” which is more important than the brand name. If they are genuinely “Made in Japan,” they come from the Takaski factory, which at this point in time produces the highest quality low self-discharge NiMH AA and AAA batteries in the world, according to every third-party test to date. Therefore, if I am ordering low self-discharge AA or AAA batteries online, I need to be assured they come from Japan.

I can be assured low self-discharge NiMH batteries come from Japan when I buy from Fujitsu, or Eneloop for those of us living in North America, Europe, or Japan. I’m also confident that the Amazon Basics low self-discharge batteries are at least 2nd generation cells from Japan. Thus, my recommendations are:

For basic performance low self-discharge batteries, get Fujitsu or Panasonic’s Eneloop brand for the latest generation, or for the budget conscious, second generation cells from Amazon which lag slightly behind in overall performance:

Regular Capacity AA LSD NiMH batteries:

Fujitsu Ready-to-use 8 AA rechargeable NiMH batteries HR3UTC 2000mAh

Panasonic Eneloop 8 Pack AA NiMH Rechargeable Batteries

Budget brand (lower quality for lower price):

AmazonBasics AA Rechargeable Batteries (8-Pack) Pre-charged


Regular Capacity AAA LSD (Low Self-Discharge) NiMH batteries:

Fujitsu Ready-to-use 8 AAA rechargeable NiMH batteries HR4UTC 800mAh

Panasonic BK-4MCCA8BA Eneloop AAA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries (Pack of 8)

Budget brand (lower quality for lower price):

AmazonBasics AAA Rechargeable Batteries (8-Pack) Pre-charged

The above batteries are fine for virtually all ordinary applications, but in high drain devices used very frequently such as digital cameras, portable fans, or microphones, you may want higher capacity so as to avoid frequent recharging. This will be especially important for those who use such devices professionally. High capacity low self-discharge NiMH cells cost more and only last for 500 rechargers, but they typically have a much higher capacity of 2550 mAh for AA batteries, and 950 mAH for AAA batteries:

High Capacity AA LSD (Low Self-Discharge) NiMH batteries:

Panasonic Eneloop Pro 4 Pack AA NiMH Rechargable Batteries

Budget brand (lower quality for lower price):

AmazonBasics AA High-Capacity Rechargeable Batteries (8-Pack) Pre-charged

High Capacity AAA LSD NiMH batteries:

Panasonic BK-4HCCA4BA eneloop Pro AAA New High Capacity Ni-MH Pre-Charged Rechargeable Batteries, 4 Pack

Budget brand (lower quality for lower price):

AmazonBasics AA High-Capacity Rechargeable Batteries (8-Pack) Pre-charged

You need to make sure you have a good charger, as explained in the next section. If you use a low quality charger, it will end up undercharging, overcharging, and/or decreasing battery longevity.

If this is your first time buying low self-discharge batteries, or this is a gift for someone who doesn’t have any yet, you may want a starter bundle that includes one of the good budget chargers. Both the Pansonic and Fujitsu chargers included in the following bundles are great chargers that are discussed below.

Panasonic has several Eneloop Bundles that include both AA and AAA batteries along with it’s competent charger:

Panasonic Eneloop Kit 10 AA 4 AAA batteries & Charger 2100 Newest 4thGen

Panasonic KJ17MCC82A Eneloop Power Pack for 8AA, 2AAA, 2 C Spacers, 2 D Spacers, Advanced Individual Battery Charger

Panasonic K-KJ17MC124A eneloop Super Power Pack, NEW 2100 Cycle, 12AA, 4AAA, 2 “C” Spacers, 2 “D” Spacers, Charger

Panasonic K-KJ17KHC82A eneloop pro NEW High Capacity Power Pack, 8AA, 2AAA, with “Advanced” Individual Battery Charger

And if you want a faster charger (bundled with AA batteries only), you can get the following Fujitsu bundle:

Fujitsu FCT344AUFX(CL) AA / AAA Ni-MH Battery Quick Charger with 4-pack 2000 mAh AA Rechargeable Batteries

What Every Charger Needs, Including Budget Models


This section was moved to the most recent battery update post.

Extra Features that Justify Buying a More Costly Premium Charger

This section was expanded and moved to the most recent battery update post.

Recommended Budget Battery Chargers

This is the category that has changed most over the past few years, as budget chargers seem to come and go. Last year I only recommended one budget charger at first, as several models I had previously recommended were all discontinued. Another was available for a few months in the U.S. but it was discontinued and quickly sold out.

This year, I’m aware of 3 good models. The 2 available in the U.S. are:

Panasonic BQ-CC17SBA Eneloop Advanced Individual Battery Charger with 4 LED Charge Indicator Lights, White

Fujitsu FCT344AUFX(CL) AA / AAA Ni-MH Battery Quick Charger with 4-pack 2000 mAh AA Rechargeable Batteries

Update 3/13/17: For more detail than is provided in this section, see this site’s recently published comparison of 3 budget chargers: BQ-CC55 vs FCT344 vs BQ-CC17.

I have tested the Pansonic Eneloop BQ-CC17SBA charger extensively and recommended it last year. It is still my top recommendation this year it for its simplicity, effectiveness, and gentle treatment of batteries. You can read my in-depth Eneloop Charger review for detail, but the most relevant thing you need to know is that it does exactly what is outlined above in the budget charger requirements section, and no more. It charges at the slow rate of 300 mAH for AA, 150 mAH for AAA, so batteries never get hot. Part of what makes it so great is that it works with a wide variety of NiMH battery types and quality, including old high self-discharge NiMH batteries.

However, for those who want faster charging and who use nothing but low self-discharge batteries, the Fujitsu charger (which only comes as part of a bundle with four AA batteries) is currently a good second option. I found after months of use that it does exactly what is claimed on the package: charges at a moderately high rate when 3 or 4 bays are occupied, and a very high rate when 1 or 2 battery bays are occupied:

Charging Rates for the Fujitsu Quick Charger FCT344
Battery Type Number of Batteries Charging Rate
AA 3-4 (normal) 550mA
AA 1-2 (quick) 1100mA
AAA 3-4 (normal) 280mA
AAA 1-2 (quick) 560mA

When charging at such high rates, there is a danger that batteries can overheat, so some form of heat detection is needed. This charger has it, and it was in fact triggered every time I attempted to charge some low-quality high self-discharge NiMH batteries I had lying around (6 years old).

In fact, that is a significant drawback of this charger—you don’t want to charge 1 or 2 old, low-quality high self-discharge NiMH batteries that have high internal resistance. They will overheat and stop charging in less than 15 minutes. This occurred even with 4 such batteries charging at the lower rate, though they took longer to warm up and trigger the cutoff.

But there’s no reason to keep using old NiMH batteries of the high self-discharge variety. I only keep mine around in order to test chargers—I’ve long ago quit using them in any of our devices.

When I first published this article, I recommended this Fujitsu charger above the Panasonic. But I have since changed my mind. Occasionally, the Fujitsu charger refused to charge my older Eneloop batteries that have developed some internal resistance over time and have lower maximum capacity than they used to.

If you’re willing to stick with high quality, low self-discharge batteries, occasionally weeding older ones (that have begun to decline in capacity and increase internal resistance), the Fujitsu Quick Charger is still a good choice among budget chargers. And you can get it, plus four low self-discharge AA Fujitsu batteries, for less than $30. That is a great deal.

TIP: AA and AAA NiMH batteries will function better for longer if you usually charge them at a slow or moderate rate. Therefore, with the Fujitsu Quick Charger or other chargers that offer high charging rates, only use the quick charging feature sparingly. Charging 3 or more batteries at a time in the Fujitsu model keeps the charging rate lower, and will prolong battery life over the long run.

Panasonic also makes a similar fast charging model, the BQ-CC16 charger, but it is not available for sale in the U.S.

Recommended Premium Chargers

My recommendations in this section are nearly identical to last year’s recommendations: Choose between 5 chargers and 3 brands: Powerex Maha, and 2 each from Opus and La Crosse. I have extensively tested and used the 2 La Crosse models, and the others I know about from poring through many reviews.

One thing about La Crosse you should be aware of is that, despite producing a quality product, they have a reputation for poor customer service. I have never had a problem with either of my two La Crosse chargers. However, if you look through Amazon reviews, you’ll find that those who do experience issues with their charger have a very difficult time getting through to customer service. Chances are low you’ll experience a charger failure, but keep in mind it could be quite a hassle if you do.

At roughly $35, one of the least expensive models that does what a premium charger should do is the La Crosse BC-700. It is easy to use and it does everything the other more expensive La Crosse models do except that charging is limited to a maximum rate of 700mA. Included with the charger is a wall power supply, and nothing else:

La Crosse Technology BC-700 Alpha Power Battery Charger

If you’re never in a rush to recharge batteries, then there’s no reason to charge faster than 700mA. In fact, 500mA is a great charging rate for AA batteries, and 200mA for AAA batteries, in order to maximize battery life. Charging at a higher rate on occasion won’t hurt the battery much, but if there’s no reason to rush, then don’t, because charging at a high rate generates heat. Heat reduces battery life.

If you want to charge at higher than a 700mA rate, use one of the other 4 chargers. The La Crosse model that does this is:

La Crosse Technology BC1000 Alpha Power Battery Charger

The BC1000 charges at a rate of up to 1800mA for AA batteries. That can overheat many batteries but the BC1000 contains circuitry that prevents overheating. Two prior models of La Crosse, BC-900 or the BC9009, were not able to prevent overheating in all cases so avoid these two models which can harm batteries and in rare cases melt batteries and/or cause fires.

The BC1000 overheat detection circuitry works reliably. This more expensive model also includes a carrying case, adapters for C and D battery sizes, and low quality, high-discharge NiMH batteries.

There is one issue with all La Crosse models that has tripped people up, including me the first month I used it. If NiMH battery voltage drops too low, it triggers a cryptic “null” message when inserted into the La Crosse charger. The manual suggests that this means the battery is no longer usable. Rarely is this true. It usually just means that the voltage is very low.

There are 3 different ways to correct this if you own a La Crosse charger:

  1. Insert the battery into a different charger, even a dumb charger, for 30-60 minutes. Then reinsert into the La Crosse charger.
  2. Leave the battery in the La Crosse charger for several days. There is a tiny trickle charge that will eventually revive the battery enough to start charging normally and make the “null” message goes away.
  3. For more rapid revival, use the paperclip trick.

Of course, you can avoid this hassle altogether by getting an Opus or Maha charger.

The Maha charger tends to be the charger preferred by geeks diehard battery enthusiasts. It offers more control and options and a slightly higher charging rate than other premium chargers. It is larger for better heat dissipation. It doesn’t have difficulties charging excessively drained batteries.

However, the Maha is by some accounts the most difficult charger to use. For example, according to popular Amazon reviewer NLee the Engineer, it needs many more button presses than the La Crosse to increase the charge rate for a set of 4 batteries. This is a very common action that I take whenever I insert 4 AA batteries. With the La Crosse, that takes just 2 button presses. With the Maha, it takes many more, as each bay must be independently programmed. Another issue is a backlit display that rotates through all information every 48+ seconds. Accessing information on an individual bay or all 4 bays is much easier on a La Crosse charger.

Once you get past the interface issues, the Maha gets the job done very well. Some people are willing to take the usability hit to get the extra control and flexibility:

Maha PowerEx MH-C9000 Maha WizardOne Charger-Analyzer for 4 AA/AAA Batteries

Older versions of Opus chargers had a poor reputation for years due to overheating battery issues. However, that was solved in 2014 with a firmware upgrade to version 2.1. If you get this model, make sure you see “2.1” or higher briefly displayed on the leftmost column when turning it on. Nearly all models shipping currently should have firmware 2.1 or higher.

This model has most of the advantages of the other 3 recommended models combined into 1 package: Easy to use, flexibility/control (though not quite as much flexibility/control as Maha), and a big display. It even has a QUICK TEST feature that measures internal resistance, which is very useful for weeding out sub-par batteries. So far as I know, this is the only premium charger with this feature. On top of that, it comes in several variants, including a no frills version that is slightly less expensive than even the least expensive La Crosse model:

Opus BT-C2400 Battery Charger Analyzer Tester for AA AAA NiMH NiCd rechargeable batteries

If you also want C and D adapters, get:

Opus BT-C2000-charger-set AC 100-240V Battery Charger Tester Analyzer with C and D adapters

And here are other Opus models, which include different combinations of accessories:

Complete List of Opus Models

Storing Your AA and AAA batteries

This section was expanded moved to the most recent battery update post.

It’s not about the Brand (Eneloop), it’s about the Factory (Takasaki)

There are several NiMH manufacturing plants in China and Indonesia, but there is only one in Japan. It’s in Takasaki, Japan. So says the Fujitsu employee I interviewed in January 2016 (who asked not to identified).

This plant was owned by Sanyo until 2009. Panasonic purchased Sanyo in 2009. In order for the transaction to satisfy the authorities with regards to anti-trust issues, Panasonic was allowed to keep the Eneloop brand, but not the Takasaki factory. Panasonic quietly found a new owner for the factory: Fujitsu. Fujitsu’s FDK subsidiary has owned the Takasaki plant since December 2009.

All Eneloops were produced in this plant while it was owned by Sanyo, and for a number of years thereafter. So battery geeks consumers who actually cared about these things assumed that the Eneloop brand and the factory in Japan that produced them were one and the same.

Because other low self-discharge batteries with identical electrical characteristics existed, most people figured that Eneloop’s parent company (first Sanyo, then Panasonic) had struck deals with other battery brands, so that batteries identical to Eneloop were shipping out of the same factory. Such batteries were given cute names such as Duraloop, to represent that some of Duracell’s low self-discharge batteries were actually rebranded Eneloops.

Consumers, including myself, might have continued to believe this a good while longer. But Eneloops sourced from China began appearing in Australia in 2014. This raised questions. Why wasn’t Panasonic producing all of its batteries from its factory in Japan? The answer was that Panasonic no longer owned the factory and presumably wanted to cut costs. The FDK subsidiary of Fujitsu has owned it since December 2009.

My source told me that after the Sanyo transaction, Panasonic got full rights to the Eneloop brand, while Fujitsu’s FDK subsidiary not only acquired the Takasaki factory, but also all the intellectual property associated with the production of low self-discharge batteries. Some of the intellectual property is documented by battery enthusiasts. My source told me that not all of the technology and processes are protected by patents. Issuing patents can give out hints that may actually help the competition. So whatever advantages the Takasaki factory enjoys over the competition are a combination of intellectual property and undocumented intellectual capital.

I wish I could provide more detail than I have in this section, but my source from Fujitsu was unwilling to provide much detail, for competitive reasons. In fact, most of this story is information I pieced together from CandlePowerForums, and the websites of Panasonic and Fujitsu. My source from Fujitsu didn’t contradict any of this information, suggesting that I have the story correct. However, I’ll be sure to update this section with any additional details I manage to come across.

However, the bottom line is clear. Takasaki has superior knowledge of how to produce low self-discharge batteries, some of which is protected by intellectual property, some not. If you want the highest quality rechargeable low self-discharge NiMH batteries, make sure it says “Made in Japan.”

When it Makes Sense to Use Alkaline or Lithium Batteries (hint: rarely)

This section was expanded and moved to the most recent battery update post.

Concluding Remarks

The product landscape for AA and AAA batteries and chargers hasn’t changed all that much over the past 5 years, when I first began writing about it. A bit of upfront investment in rechargeable, low self-discharge NiMH batteries along with a decent charger continues to be the most effective and most economical way to use AA and AAA batteries. The majority of people don’t know this, because for most people the cost of AA and AAA batteries is low enough that they don’t want to spend much time thinking about it.

However, there are people (i.e. families with young kids) who have dozens of AA or AAA batteries in their various devices at any given time. If you think about how much that costs financially and environmentally over time, and how often batteries need to be changed, you’ll realize that it’s worthwhile to learn about the best AA batteries.

The best of the best AA and AAA batteries continue to be low self-discharge rechargeable NiMH batteries sourced from a factory in Takasaki, Japan. Given that this factory is owned by Fujitsu, the Fujitsu branded AA and AAA NiMH batteries will always be a safe buy. Eneloop and other “pre-charged” NiMH battery brands will also be of high quality, so long as they are “Made in Japan” because the Takasaki plant is the only NiMH battery plant in Japan.

As I mentioned in a prior article, buying low self-discharge NiMH batteries is like buying a cast-iron skillet. It’s a little more expensive up front and it has a little bit of a learning curve, but it will last a life time. We live in a world where we continue to generate exponentially increasing amounts of garbage. I would rather use my batteries for a lifetime, rather than just once. I’m hoping that hundreds of millions of people will join me.

Author: Joe Golton

I’m a dad with a son who loves baseball. Professionally, I’ve been a software developer, investor, controller, and logistics manager. I now make my living from this blog, supplemented with occasional consulting gigs.

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