Eneloop Panasonic BK-4MCCA8BA AAA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries, 8-Battery Pack

Just arrived so durability is not available. Replaced batteries in handset of Panasonic DECT system that I've owned for years. Previous batteries were 300ma storage upper limit while these are a little more than double that. Eneloop is made by Panasonic so I assumed close compatibility to their higher priced custom replacements. They charged for six or seven hours and reached full. Dial tone is clear. All is good.Also, I went online and found someone who decoded the Eneloop date stamp on the battery. I bought these in Apr 2025 and the stamp showed a manufacturing date of rough;y 9 months ago. I'm very happy with that. Also, made in Japan. Identifying the date is not easy as it is embossed and not printed. You need to get the light-shadow just right when you take a picture. First two numbers are year and next two are the month. Pretty clear.

The Panasonic eneloop AAA rechargeable batteries are fantastic! I’ve been using them for several months now, and they are incredibly reliable. The 2100 cycle life is a huge plus, and they hold a charge for a long time. They come pre-charged, so you can use them right out of the package, and they perform consistently in my devices, whether it's remote controls, flashlights, or other everyday gadgets. These batteries have saved me money in the long run and are much better for the environment than disposables. Highly recommend them for anyone looking for dependable, long-lasting rechargeable batteries!

[this review is for the AAA 8 pack, although much of the information applies to other Eneloops.]The batteries arrived packaged on a card as shown in the photo on this page. I confirmed these are the latest 4th generation Eneloop batteries as advertised. The date of manufacture is imprinted on every battery, and although difficult to see, I found this set was made 5 months prior to receipt.With any low self discharge battery (LSD NiMH), one should perform an initial and periodic "conditioning" comprised of charging and discharging the cell 3-5 times in a charger that has this function (sometimes called "refresh") in order for the cells reach their maximum energy storage capacity. After conditioning the AAA batteries, all 8 exceeded 750mAh capacity (the advertised minimum), with values ranging from 762mAh to 778mAh. The very narrow range is an indicator of high quality and consistency in the manufacturing process.What follows are general recommendations to get the most from Eneloop and other LSD NiMH rechargeables....Get a good quality charger if you use Eneloops or other LSD NiMH batteries. Cheap chargers will significantly shorten the life of these high quality and somewhat expensive rechargeable batteries. The charger must be a microprocessor controlled "smart" charger that chargers each battery individually, not in pairs. I use a Titanium "smart fast" charger when bulk charging many batteries, and a Opus BT-C2000 when trying to get accurate measurements on capacity and internal resistance. These are there several others good quality chargers out there so be sure to read reviews from people who understand and discuss the technical aspects of battery chargers. That 15 year old old battery charger you have that came packaged along with some long since thrown away rechargeable batteries should not be used.Not all devices are designed to work with rechargeable batteries. The nominal voltage of rechargable NiMH batteries, 1.2 volts, is less than the alkaline equivalent at 1.5 volts. Some devices work well with either one and some are only designed for the higher voltage alkaline. This not a problem with the battery, it is a problem with the way the device is designed. Unfortunately it's rare for a device manufacturer to mention how (or if) it works with rechargeable batteries so you will have to test it or read the experiences of others.Devices that display the amount of power left in a battery will be inaccurate when using rechargeables and tend to indicate the batteries have less power than they really do. A device may show 2 out of 4 bars, when in fact the Eneloop might really be at 85% of charge.Rechargeable batteries like Eneloops (LSD NiMH), store 20-35% less energy than a good quality alkaline of the same size. This is not a "problem" with the rechargeable battery, it is a characteristic of the chemistry and how the energy is stored. That means you can not expect them to last as long between charges as an alkaline before replacement in most applications. LSD NiMH batteries however do hold more energy and last longer than carbon zinc batteries aka "heavy duty" (these are the really cheap batteries you may see at the dollar store or come prepackaged with low end flashlights).Rechargeable batteries should not be *over* discharged as it will damage them. Unfortunately it's hard to tell exactly when the ideal time is to recharge so it's better to stay on the safe side and recharge early when device performance starts degrading and not wait until it's completely dead. The best way to tell for certain is to test with a battery tester that measures voltage under load and recharge when the battery gets to about 1.1 volts Even some cheap battery testers can do this (look for BT-168D) or for a more expensive one the ZTS mini 9R. If all you have is a voltmeter, recharge when the open circuit voltage at rest is about 1.22v.Rechargeable batteries should not be charged too quickly as the internal heat build up will damage them. For AAA NiMH, it should take 2-5 hours to charge fully depleted batteries. If your charger goes from empty to full in 30 minutes, it is either damaging or under charging the batteries.Devices that automatically charge the batteries, such as cordless phones or cheap solar lights, are not a good candidate for Eneloops. These devices use "dumb" charging circuits and will likely overcharge the batteries shortening their life. For these types of batteries you are better off with cheap NiMH batteries that are not marketed as low self discharge (LSD).Devices that use a very small amount of constant power, such as a battery powered clock, might be better off with an alkaline. An alkaline may only need to be replaced every 3 years in such applications, where as the rechargeable may need charging in less than a year due to higher self discharge rate and lower nominal voltage. You will need to test it to be sure and decide what makes the most sense.Infrequently used low power devices such as a TV remote in a spare bedroom are usually better off with alkalines. A high quality alkaline may last 5 or more years, and the cost/benefit of an LSD NiMH just isn't there. Be cautious of low quality batteries this these sorts of applications as the battery may leak after a couple of years.Eneloops (and LSD NiMH in general) are better than alkalines in high current applications. An Eneloop can move energy faster to the device than an alkaline. Examples where LSD NiMh out perform alkalines are modern photographic flashes, remote controlled cars/planes, certain high output flashlights.Marking your batteries is a good idea, especially with you have many purchased at different times that all look the same. I mark mine by putting the year/month I purchased them, followed by a unique letter. When I first get them, I test their capacity and log it for future comparison. Even if you don't have the equipment to perform extensive testing, just knowing when you purchased each battery can be helpful down the road.Properly managed, high quality LSD NiMH batteries like Eneloops will give a long life. Abused, they will not do any better than cheap NiMH batteries. Most of the complaints and bad reviews are from people who do not understand the limitations, use them in the wrong application, or who do not properly charge them. Correctly using rechargeable batteries takes some work and isn't for everyone, but if you can deal with their idiosyncrasies, they can save a lot of money in the long run.

The Panasonic BK-4MCCA4BA eneloop AAA rechargeable batteries are a top choice for anyone looking for reliable, eco-friendly power. Their long lifespan, low self-discharge, and pre-charged convenience make them a great investment for households and offices that use AAA batteries regularly. While the initial cost is higher than disposable batteries, the long-term savings and sustainability make them a fantastic value. Highly recommended for anyone looking to power their devices efficiently while reducing waste!

Long-lasting, eco-friendly, but initial charge takes time

These eneloop AAA batteries are fantastic! They hold a charge well, last long, and live up to the 2100-cycle promise. Perfect for high-drain devices like remotes, toys, and flashlights. The pre-charged feature is convenient, and the consistent performance is impressive. Highly recommend for anyone needing reliable, eco-friendly rechargeable batteries. Great value!

The Panasonic eneloop AAA rechargeable batteries (BK-4MCCA4BA) are highly regarded for their exceptional performance and longevity. These Ni-MH (Nickel-Metal Hydride) batteries hold a charge for an impressively long time, even when not in use. With up to 2100 recharge cycles, these batteries provide great value for anyone who uses high-drain devices or needs batteries that can stand up to regular use.

I’ve been using Panasonic Eneloop AAA rechargeable batteries for a while now, and they continue to impress me. The 2100 cycle life is a game-changer, and these batteries hold up incredibly well over time. Whether I’m using them in my remote controls, cameras, or kids' toys, they consistently deliver solid performance.