I recommend only one inexpensive battery charger among hundreds of possibilities. It is the Panasonic Eneloop BQ-CC17 which can be had for $15 at Amazon in white or black, or as part of several possible bundles that include Eneloop batteries.
Update 3/12/17: A new post on this site compares this charger with two other budget chargers that have faster charging rates. The BQ-CC17 compares favorably. See Best of the Budget Chargers.
I bought a BQ-CC17 bundled with Eneloops two months ago. The rest of this post is my review of the included BQ-CC17 charger, as well as the criteria I use to eliminate other low cost chargers from consideration.
What Makes for a Good AA Battery Charger
When I first started writing about AA batteries and chargers a few years ago, there were several worthy, low cost chargers on the market. I recommended three of them. All have been discontinued.
I go into great detail about what makes for a truly outstanding battery charger in my La Crosse AA Battery Chargers post. La Crosse and several other outstanding charger models offer numerous features that go far beyond what I consider to be minimum requirements. But these premium models cost $35 or more. If you use lots of AA batteries and don’t mind the extra cost, then I suggest you pick one of the premium models described in this comprehensive post about batteries and chargers:
The criteria for buying a good battery charger boils down to the phrase, “smart charger.” This is a marketing phrase. It generally means that the charger has one or more features, the most important of which is that it contains circuitry to stop charging batteries when full. The quality of full battery detection varies depending on method, with the “negative Delta V” method generally considered the most reliable.
Many inexpensive chargers contain this one feature, and quite a few use the “negative Delta V” method. The problem is that very few contain a second “smart” feature that is also very important: individual charging channels for each charging bay.
Nearly all low cost models charge in pairs. A typical 4 charging bay model has two pairs of two. In each pair, if the charger stops charging when the first battery is fully charged, then the second battery will be only partially charged. Alternatively, if the charger stops charging when both batteries are full, then one battery has been overcharged, which shortens the life and effectiveness of the battery. In either case, an unsuspecting consumer will think that there is something wrong with their batteries, when the fault is using a paired bay charger. Also, paired chargers require that both batteries in each pair be either two AA or two AAA batteries, so another advantage of individual charging bays is being able to put in any mix of AA or AAA batteries in any order you want.
I did not need to test hundreds of chargers to identify this one good model. I just read through the descriptions and reviews for all the inexpensive models I could find on Amazon (U.S.). I found only one with both full battery detection and independent charging bays. It is therefore the only one I recommend. If anyone reading this knows of another low cost model with independent charging bays, please leave a comment.
Everyday Use of the Panasonic Eneloop BQ-CC17 Battery Charger
When reviewing products, I don’t like conducting numerous artificial tests over a period of a few days. I prefer using a product over a few weeks (or longer) as just a regular user. After two months of use, I have the following observations:
First, and most importantly, the BQ-CC17 lives up to its claims. Batteries are never hot to touch when charging occurs or is complete. Upon charge completion, all batteries are always full (I can tell by placing into my La Crosse charger). That’s exactly what I wanted to see—a confirmation that independent charging bays work independently.
Despite its small size, I have no trouble inserting or removing AA batteries. However, I found inserting smaller AAA batteries puzzling at first as I am used to laying them flat in other chargers. I couldn’t get that to work. The included instructions make clear that AAA batteries do not lie flat in the charger, but rather at a slight angle. After inserting AAA batteries a few times I got used to it.
The charger is small and light. It has no power cable, but rather a retractable plug, so it is more compact and convenient to travel with than premium chargers that are twice as large. It accepts 100-240V AC, so it can be used worldwide if an inexpensive adapter plug is purchased.
There are no options of any kind. You simply insert batteries, and see a solid green LED light come on for each battery bay that contains a partially charged battery. Each individual bay has its own LED light, a handy feature not available in most chargers. Once an individual battery is fully charged, the light for that bay turns off. The AA battery charging rate is 300mA, while the AAA battery charging rate is 150mA.
The included instructions say “LED charge indicator lights will begin blinking rapidly after plugging the device in to the AC outlet.” This does not happen on my BQ-CC17. However, I have seen a rapidly blinking light when a battery is failing to charge.
I did not understand what the blinking light meant at first. After much experimentation, I observed that the blinking light never occurred with low self-discharge batteries such as Eneloop. My testing included a couple older AA Eneloops with maximum capacity of only 1700mA. It only seems to occur on older, low quality, high-discharge batteries which could no longer charge to full capacity. It doesn’t matter whether the charge is full, partial, or empty—the LED blinks rapidly to indicate an error condition and refuses to charge these older batteries.
This could be viewed as a negative, in that this charger can’t charge older, low quality batteries. Or this could be viewed as a positive: the blinking light is a simple way to identify batteries that you want to throw out because of high internal resistance and low maximum capacity.
I never recommend high self-discharge batteries as they are far less convenient to use than low self-discharge batteries such as Eneloop. I’m guessing those who stick with high quality low self-discharge batteries will never notice rapidly blinking lights as a battery fails to charge. If you do see the blinking lights, you probably have a battery that is no longer worth keeping.
I consider the biggest drawback of La Crosse chargers to be their failure to charge over-discharged batteries because the voltage drops too low. The BQ-CC17 charges such batteries so is a useful complementary charger for those who already own a La Crosse model and occasionally see the “null” message.
The only thing not to like about the BQ-CC17 is the relatively slow rates of charging. A fully depleted AA battery will take over 7 hours to charge. The one and only change I would make to this model is to have the charging rates be 500 mA for AA batteries and 200 mA for AAA batteries. So far as I know, these rates are just as gentle on batteries as 300/150 rates (note though that rates higher than 500mA for AA and 200mA for AAA are known to decrease battery life). If you always have an extra set of fully charged batteries available, the slow charging rate won’t matter.
If charging more rapidly on occasion is important to you, consider purchasing one of several good premium chargers.
It’s hard to understand why so many mediocre chargers exist. I suspect that it’s because of the low price. Most people won’t spend more than a minute or two on a $15 purchase, because it hardly seems worth the time.
Well, it turns out that taking the time to buy a decent charger will result in batteries lasting longer between charges, and therefore fewer battery changes. Taking 5-10 minutes to choose a good charger may end up saving a lot more than 5-10 minutes in the long run.