Just about everyone uses AA batteries. But few people use the best AA batteries, or have even heard of them.
What are these batteries? Why are they so great? Where can you buy them? What charger do you need to buy?
It’s Eneloop. Low self-discharge, 1500 recharges.
That’s the short answer. Here’s the long answer:
What are Eneloop Batteries?
Update: The explanations in this section remain accurate. However, some products discussed in later sections have been updated or discontinued. For updated product information, see 2015 AA Batteries update.
Eneloop batteries are a low self-discharge version of NiMH AA rechargeable batteries. Low self-discharge rechargeable batteries lose energy very slowly when sitting idle. This type of battery was pioneered by Sanyo in 2005 but has since been copied by many other brands.
Eneloops are difficult to market because the benefits cannot be clearly communicated in one or two short phrases. The packaging for these batteries typically communicates that they are “pre-charged” in large letters. The fact that they are low self-discharge is mentioned in the fine print. Few people know what low self-discharge means, and even fewer will learn by reading a technically detailed article.
In layman’s terms, here’s why low self-discharge batteries like Eneloop are so much better than Alkaline or high self-discharge NiMH batteries:
Why the Best AA Batteries are Eneloop Low Self-Discharge NiMH Rechargeables
Batteries store energy. Batteries “discharge” their stored energy to provide power to gadgets. Batteries also “self-discharge” their energy when not in use. An unused battery will eventually self-discharge so much energy that it will no longer be able to provide any power.
Devices use energy, often from batteries. “High drain” devices like digital cameras drain batteries quickly. “Low drain” devices like remote controls drain batteries slowly.
Alkaline AA batteries are very popular. They’re cheap. They perform well in low-drain devices. Voltage starts higher than NiMH batteries at 1.5 V (certain devices require this). Most important is their low self-discharge rate. You can buy an inexpensive bulk pack with dozens of AA Alkaline batteries. Idle Alkaline batteries will still work 3-5 years after purchase, or even longer if stored in cool, dry conditions. But two properties of Alkaline batteries motivate people to seek alternatives:
- They are single use. When depleted, you’ll have to spend time and money to buy more. You’ll also send many batteries each year to a landfill or hazardous waste facility.
- Alkaline batteries perform poorly in high drain devices such as digital cameras.
Before Eneloop came along, high self-discharge rechargeable NiMH (Nickel Metal-Hydride) AA batteries were the preferred option for high drain devices. They perform better than Alkaline in digital cameras. They can be recharged hundreds of times. Instead of buying a few dozen Alkaline batteries per year to power your digital camera, you can rotate two sets of rechargeable batteries between the camera and the charger every few weeks.
High self-discharge NiMH batteries can be inconvenient to use, because:
- The self-discharge rate is too high. For 2400 mAh batteries, 20% to 30% of stored energy discharges in just the first month. Higher capacity batteries discharge even faster. The stored energy discharges completely in just a few months.
- Managing rechargeable batteries is a chore. A typical family with children may have 15-30 devices that have 30-60 AA or AAA batteries. Rotating batteries out of 15-30 devices every 3 months is time consuming, to say the least.
Enter Eneloop. These batteries are suitable for all devices. Like Alkaline batteries, they self-discharge at a low rate. They perform as well in high drain devices as high self-discharge NiMH batteries. So these batteries are well suited for both remote controls and digital cameras. But that’s not all. The original Eneloop batteries can be recharged 1000 times. They last 83 years if recharged once/month. The newer Eneloops recharge 1500 times, or 125 years if charged once/month.
And let’s not forget the very best benefit. Need batteries right away? Put ‘em in. Like Alkaline batteries, idle Enloops retain most of their charge for years: 85% after 1 year, and 75% after 2 years. So it hardly matters if your Eneloops haven’t been charged for months. They’re ready to go. That makes them more convenient to use than high self-discharge batteries.
Eneloops cost a little more than high self-discharge NiMH batteries and much more than Alkaline batteries. But they perform better and can be recharged 1000 times. So buying Eneloops results in lower costs and energy use over the long run, less time recharging, fewer trips to the store, and a smaller number of batteries going to the land fill.
But Isn’t 2000mAh Low?
Wait a minute, you say. Eneloop batteries have just 2000mAh, while other NiMH batteries have 2600mAh or more. Less mAh (milliampere-hours) means less stored energy right? Yes. But only when fully charged.
Five weeks after you take both types of batteries out of a charger, they will all have around 1900-1950 mAh remaining. Five months after you take both sets of batteries out of a charger, Eneloops will have 1850-1900 mAh remaining while high self-discharge batteries will be close to dead. This leads to the following practical advice for digital cameras or other high drain devices:
If you use a digital camera to take flash pictures just a few times per week, you’re much better off using low self-discharge batteries such as Eneloops. They’ll last longer thanks to lower self-discharge rates. A spare set of Eneloops kept with the camera will be useful even if they haven’t been charged in a while.
If you use a digital camera to take hundreds of flash pictures per week, you’re better off using high self-discharge NiMH rechargeable batteries rated for 2600mAh or higher. Just make sure that the 2600mAh batteries you insert into your camera are fresh out of the charger.
Best AA Batteries to Buy
I recommend Eneloop over competing brands. They were first. They continue to improve. They make accurate claims. You know what you’re getting when you buy an Eneloop: low self-discharge, high quality NiMH batteries.
Some competing brands are a little cheaper, some offer slightly higher capacity, and some offer other minor advantages. But the marketing claims for these subtle benefits are sometimes misleading and often confusing. Some brands use nearly identical packaging for both the low discharge and high discharge batteries. And just because a brand claims a higher mAh rating doesn’t necessarily mean it’s better than Eneloop, as this battery comparison demonstrates. Given the low cost of batteries, and Eneloop’s great track record, I’m not willing to spend the time and effort to find a slightly better battery than Eneloop.
All Eneloop batteries are low self-discharge. All come pre-charged between 60% to 80% full. But there are now three different kinds, which I will call the “old,” the “1500” and the “XX.”
I prefer the new Eneloop 1500 since these batteries became available in late 2010, but I describe here the differences between the 3 versions so you can make the best choice for you:
Old Eneloop: The old Eneloops are very similar to the newer 1500s, and for many practical purposes are the same. Both are rated for 2000mAh. The discharge rate is only slightly worse. And not too many people are going to care if once/month recharges will last for 83 years or 125 years (1000 versus 1500 recharges).
One thing caught me off guard with my first purchase of the old Eneloops. When you first charge them, they only reach 92% to 98% of their advertised 2000 mAh capacity. Each battery must go through 3-5 cycles of full discharge followed by full recharge in order to reach or exceed the stated capacity of 2000mAh.
To reach maximum capacity, you’ll need to “condition” (also called “refresh”) each Eneloop battery. Conditioning means to discharge and recharge repeatedly until a battery reaches full capacity. Repeatedly “testing” a battery can accomplish the same thing, but requires more steps.
Though old Eneloops typically sell for 5% to 20% less than the 1500 Eneloops on Amazon, I don’t recommend them anymore because for the minor price difference you may as well get the 1500 Eneloops which are better in several minor ways.
1500 Eneloop: The new 1500 Eneloops are similar to the old Eneloops in both appearance and performance. Packages containing the new Eneloops have “Recharge up to 1500 times” printed on the package. Sanyo claims several subtle advantages for the 1500s over the old Eneloops. These advantages are:
- slightly lower self-discharge rate (85% remaining after year 1, 80% after year 2, 75% after year 3, as compared with 75% remaining after 2 years for the old)
- they can operate at lower temperatures (-20 C vs. -10 C)
- they can recharge more times (1500 vs. 1000)
In my view, the biggest advantage is not even advertised: The first time you charge a 1500 Eneloop, it will almost reach the rated capacity of 2000mAh. After just two rounds of discharge/recharge, it will reach maximum capacity. I’ve also found that maximum capacity of the 1500 Eneloops is higher than the old Eneloops by 1% to 3%.
Furthermore, 1500 Eneloop batteries now state “minimum 1900 mAh.” In my tests, this proved to be true after one round of discharge/recharge for all 8 batteries (low of 1933mAh). All were at least 2030 mAh after the second round of discharge/recharge. Subsequent discharge/recharge cycles did not increase capacity.
The 1500 Eneloops typically cost 10% to 20% more than old Eneloops. In my opinion, the extra convenience is worth the slightly higher cost. List price is $26.99 for 8, but Amazon sometimes sells 8-packs for less than $22:
XX Eneloop: The 2500mAh XX rated capacity is 20% higher than other Eneloops and most of the competition. However, they cost over twice as much as regular Eneloops. Also note that they can be recharged 500 times and will retain 75% of the charge after 1 year. If you value your time far more than your money, these are the batteries for you:
Best AAA Batteries to Buy
Everything I’ve discussed about AA batteries applies to AAA batteries, though the smaller size means smaller capacity. Some Eneloop battery bundles include AA and AAA batteries in one package at a modest discount to buying AA and AAA batteries separately.
Which Charger to Buy?
All NiMH batteries need to be charged with “smart chargers” which won’t overcharge. Unfortunately, charger quality is all over the map, and most cheap chargers should be avoided.
Sanyo only guarantees their batteries if you buy an Eneloop or Sanyo branded charger. The least expensive way to get an Eneloop charger is to buy it as part of a battery bundle.
According to avid Amazon battery charger reviewer NLee the Engineer, the Sanyo Eneloop MC-MQN06U NiMH 4-Battery Charger included with most Eneloop bundles is mediocre and should be avoided. The critical missing feature from this and many other lower quality chargers is the ability to charge each battery independently (as opposed to requiring pairs).
However, the following 2-battery USB Eneloop charger which includes 2 AA Eneloop batteries is a great combination of acceptable quality, great portability, and low cost:
If you want a four battery charger, you have a few choices, depending on how fancy you want to get.
The simplest and lowest cost charger with minimally acceptable quality is the Sony Cycle Energy BCG34HLD4KN Power Charger with 4 Pre-Charged 2000 mAh AA Batteries. The included batteries are low self-discharge NiMH batteries similar to Eneloop.
If you want to use your batteries at maximum capacity, you need to condition them with a “refresh” or some other means of repeated discharge/recharge. The above two chargers don’t do that.
The following 4 chargers have a “refresh” function. The refresh function on the first charger listed below does a single discharge followed by a single recharge. The refresh function on the 3 La Crosse chargers which follow will repeat the discharge/recharge cycle until batteries reach maximum capacity.
This Sony charger, which costs a little more than the above Sony charger, offers a refresh function, faster charging, and individual cell indicators:
The BC500 is a step up in features, including battery testing. With testing you can determine maximum capacity and identify bad batteries. The BC500 is also very portable and can charge batteries in a car using the included adapter. The BC500 sacrifices ease-of-use and has a smaller display size compared to larger models. It is best suited as a travel charger:
For additional control, easily accessible features, and a large display, the terrific La Crosse BC700 charger typically costs less than $40:
I personally use a La Crosse BC900 Charger which has a higher maximum charging rate than the BC700. Unfortunately, it was replaced by the new BC9009 which I cannot recommend due to overheating issues.
The new La Crosse BC1000 Charger is very similar to the BC-900 and BC9009 as all 3 offer a higher maximum charging rate than the BC700 and have seemingly identical features. However, the BC1000 has internal changes that may address the overheating issue. La Crosse’s web page for the BC1000 includes the language, “Overheat protection to protect battery life. If any one battery or circuit over heat, the charger will stop all channels charging and discharging.” The web page for the BC9009 does not include this language. The BC1000 is more expensive than the BC700, so only purchase this more expensive unit if being able to very rapidly recharge batteries (2 AA batteries at 1800mA, or 4 AAs at 1000mA) is important to you:
You can spend even more money on a Maha charger for a little more flexibility, a little more control and an even faster charging rate. But the Maha is harder to use. For most people, the easy-to-use La Crosse BC700 has a good enough charging rate and feature set. So I’ll stop introducing more chargers. I’ll also thank NLee the Engineer for so thoroughly reviewing these and many other chargers on Amazon.
How Do You Store Batteries?
Storing batteries at high temperature is not a good idea as it causes them to discharge at a faster rate. So be sure to store at room temperature or lower, preferably in a dry place.
Some people store batteries in their plugged-in charger. That works fine so long as you have a quality smart charger that senses when a battery is full. You can destroy batteries with a low quality charger that overcharges. For this reason, don’t use an old charger unless you’re certain it’s “smart” enough to sense when a battery is full.
I used to store batteries in a smart charger to keep them full. Then I had a kid. Toys accumulated.
Now, we have many devices that use batteries. Way too many. I occasionally swap out more than 10 batteries in a single week. In fact, it was this massive increase in battery activity that got me thinking about AA batteries in the first place.
So I have a bunch of charged spares, primarily AA and AAA. I store them in this inexpensive, wall-mountable battery holder which includes a battery tester:
Spread the Word About Low Self-Discharge Batteries
AA and AAA batteries are used in large quantity thanks to digital cameras, toys, flashlights, and a whole host of other gadgets. Since 2005, battery management has become simpler, less expensive, and better for the environment thanks to Eneloop and its low self-discharge battery competitors. Yet, most people have never heard of them. Therefore, single use Akaline batteries and high discharge NiMH rechargeable batteries continue to dominate the market.
I’d like to help change that. Hopefully, this article will help. You too can help. Here’s how:
- Consider gifting one of the battery/charger combinations described above.
- Point your friends and family to this post.
- Most importantly, replace all of your existing batteries with low discharge batteries, as follows:
Buy a few 8 packs of Eneloop 1500s the next time they go on sale. Condition them. As your Alkaline batteries die, one by one, swap in your low self-discharge substitutes.
Once you’ve swapped out your last Alkaline battery, go to the local hazardous waste faculty to drop off your dead batteries. Take a good look. You won’t be seeing this hazardous waste facility for another 83 years.