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

[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.

It definitely lives up to its reputation as the go-to or one of the best rechargeable batteries to buy on Amazon. Works well, lasts long enough, charges fine, and still working after months of extended using and recharging. 10/10

Best choice for RC cars! After getting my son a basic remote control monster truck for his birthday and only having alkaline batteries in hand, I noticed that the litte truck wasn’t accelerating quickly and would stop at the smallest obstacle. After doing a little searching, online answers directed me towards these Panasonic Eneloop. I never would have thought of getting NiMH batteries again, assuming they were made obsolete by Li-ion (last time I remember recharging NiMH I was about 10 years old); well I was pleasantly proven wrong. These batteries come already charged which that’s new to me compared to other rechargeables I’ve bought in the past. Quality of the battery cases and overall look and feel of the batteries are very good; clean design, easy to recognize and appearing built to last. So how did they perform? WONDERFULLY. My son and I can actually have some fun with his simple entry-level RC, which is a relief, since I was worried it was just a weak car and that batteries wouldn’t make a difference. Well, I not only learned something new but I got a great product.

I have these batteries from 2016. I bought more. Great value, great performance, great quality. Not sure how other battery makers stay in business against these. Flawless.

good stuff. I 've recharged probably 3 or 4 times so fa so they've pretty much paid for themselves. IF I get say 20 recharges, a bargain.

I picked up this 4 pack of Eneloop AAA batteries to stop burning through disposables in small devices and they have been great so far. They came precharged, so I was able to drop them straight into remotes and small electronics and everything powered on right away. They hold a charge very well in storage too, which is one of the main reasons I prefer Eneloops over cheaper rechargeables. In regular use they seem to last at least as long as good quality disposable AAA batteries, and when they finally run down I just top them off in my charger and put them back in rotation. No more last minute trips for batteries when a remote dies. If you have things like remotes, wireless mice, flashlights, or kids’ toys that chew through AAA cells, this 4 pack is a very solid way to start building a reusable setup.

The new battery is more higher capacity than the OEM 150mah, with a Ni-Cd, this new battery is very good as should be more longer than before. The compatibility is perfect as easy to install and ready to use as it should be when new for the led Solar lights. The speed is very good when charging on the sun. The battery lasted the whole night making it more efficient than ever before, I would recommend when upgrading the Capacity with the LED small lights, into great quality battery.

Great rechargeable batteries. Expensive, but dependable.

6 years later, and these are still the best of all the rechargeable batteries I own. I love these, I'd be dumb to even test other brands at this point.

I have a bunch of high quality flashlights that use AAA batteries and one of my US made single AAA flashlight was about to ruin when a alkaline battery started to leak in it, that's when I decided to get me a set of AAA eneloops which have excellent reviews. These are high quality made in Japan cells which can be re-charged about 2100 times. These batteries came factory charged but I did a full charge which was quick (5 mins) meaning the batteries had not lost much charge. They perform very well and the voltage is consistent and I get good runtimes on these. Would highly recommend for people with heavy usage (Toys, electronics etc..) total peace of mind.

Great product.

Great batteries. Tested them and got at least 830mah.

pilas muy buenas. sus múltiples recargas garantizan un ahorro de no estar comprando cada 6 meses