Panasonic eneloop BK-4MCCA12FA AAA 2100 Cycle Ni-MH Rechargeable Batteries with K-KJ17MCA4BA Smart Charger & 4 AA Batteries - Perfect for Cameras, Game Controllers, and Wireless Devices

This is a review of Panasonic Eneloop AAA and AA (Not Eneloop Pro) on 06 October 2022:These are advertised as "precharged" and "ready to use." Just to be sure, (Sept 2022) shortly after receiving them, I put these on my chargers (one pack of AA x 16 and one pack of AAA x 12). Two different brands of chargers--a total of 3 chargers--a total of 28 Eneloop batteries in all.They were all (28) registering only half- charged. I might have considered my equipment to be faulty except that I am using two different brands of chargers (2 chargers of a brand with 4 slots each and one charger of a brand with 12 slots--and had to do them in a couple of batches to do all 28). So, if all 3 of my battery chargers are all agreeing that there is only about a 50% pre-charge, I'm going to have to figure that's pretty much an accurate measurement.So, I don't know this result is a bad thing. But, I don't know if it's a good thing either. I don't even know if it's significant--but it seems to be--to me.Panasonic advertises these Eneloops hold something like 70% of their charge after 10 years. Well...if the batteries I received were only 50% charged, that would mean they were well over 10 years old. Or, it would mean they are only half charged from the factory. Or, it would mean they were fully charged at the factory but all 28 are defective in some way and have lost 50% of their charge in just a few months.These are packaged in those which appear to be authentic retail blister packs with "made in Japan" printed on the packages so I presume they are authentic and coming from a high volume seller like Amazon, I presume they are fresh. (These were sold by and shipped by Amazon.)For the first few uses, these are not lasting as long as I am used to with Eneloops. I have been using Eneloops for many years--going back even to the days when Sanyo branded them. This batch of 28 batteries in this recent purchase seems to run down much more quickly than they should. I don't have the equipment required to measure load/time/voltage/amperage and I don't have the time to do those tests even if I had the equipment.I can only base my "impression" on the 10+ years that I've been using Eneloops and this batch of 28 just seems a little weak and underpowered. I'll run them through some more cycles and see what happens.I would say that I'll update if I discover anything significant but lately I have had severe problems finding reviews that I've posted. I need to first find my review so I can update it. However, my reviews don't readily show up in my online profile like they used to. I can find really old reviews but I can find nothing I've done in the last several months. As a backup method of finding my original review, I have to save the product url so I can return to my review but usually the product url has changed so that the url I save is useless after some short period of time. So, if you don't hear from me on this again, I am sorry. My absence probably means my profile is still truncated and the url for the product has changed again.What follows is my completely unscientific evaluation of Eneloop batteries, which I have been using for years. I use rechargeable AA and AAA batteries is my photographic equipment, both LED and flash, and in household items like flameless candles and LED lighting, such as Christmas string lights. I have used Eneloop, both these white and the Pro version in black, Amazon Basics and loads of off brand rechargeables. When it comes to longevity, power and price, these Eneloop whites are the Best value. I did a test with flameless candles using these, the Pro Eneloop and Amazon's own brand, all fully charged and the Amazon died first, weeks before either Eneloop. While the black Pro did outlast these white Eneloop, it was not by enough to pay so much extra for them. Over the years my Eneloop batteries have outlasted every other brand. I am still using and recharging every set, while other brands have ended up in the trash. The second unscientific test I've done is just comparing them in a flameless candle to Alkaline batteries. In flameless candles Alkaline are usually known for producing more power and a much brighter light. Side by side in my photograph and in real life, these fully charged Eneloop are producing as much power to the LED in these flameless candles as the Alkaline battery. No Alkaline battery is going to last for years and the Eneloop may cost more initially, but years from now you'll still be using them.[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.What can I say about these batteries? I was expecting a way better product. Seven of the sixteen batteries failed within a week. They show "Err" on the battery charger and are beyond recovery. After two weeks of use many of the remaining cells show little ability to hold a charge and have a capacity of less than 40mAh. These batteries were fully charged before deployment and were used to operate small ornaments, each with 3 LEDs - not a challenging load. None were allowed to fully discharge before cycling again through the (miboxer) charger. I had purchased 12 EBL batteries at the same time and all of them continue to function ad expected. I'm quite disappointed with the Eneloop batteries. They are highly rated but my experience was different and I cannot recommend them. Maybe just a bad batch. I threw the first one in the garbage not expecting so many to fail now I can't even return.I bought some of these batteries 10 years ago and most of them still perform very well. They can stay charged in storage for a long time without loosing their charge. The reason I didn't put 5 stars is because they arrived uncharged, completely empty. It took about 6 hours per set of 4 to charge. I didn't try this batch yet so I hope they will perform at least as well as those I bought 10 years ago but the fact that they arrived uncharged and I don't know how long they were in that state makes me suspicious. I use the first batch in everything, my Panasonic cordless phones, all my remote controls, mice, etc. This is an excellent product and I highly recommend it.El pedido lo hice el 15-Mar-2021 y me llegaron el 20-Mar-2021.Ya habia comprado estas baterias anteriormente y me salieron muy buenas.Ahora compre esta caja con 24 y medi el voltaje de cada una de ellas y marco 1.345V.Esto es, ya vienen precargadas.De cualquier forma cargue un par de horas las baterias antes de ponerlas en los controles donde las voy a usar y marcaron 1.45V.Recomiendo al vendedor y a las baterias al 100%.Compro estas pilas casi desde que salieron en japon, bajo la marca ahora inexistente, Sanyo.siempre me han funcionado bien y han sido muy favorita. este paquete de 24, salió más barato de lo esperado y son de las que más se usan en la casa, controles de televisión, Set top box, etc.No he utilizado todas las pilas, pues las compre como repuesto y para que no falten, pero las que he usado saliendo con la misma calidad que esperaba que salieran. son duraderas y de las pilas que tengo, incluso de hace unos 4 o 5 años, siguen funcionando bien.There's a reason these are the benchmark for Low Self Discharge batteries; they're that good. They are now the only batteries I buy. I use them for everything ... wireless headphones, headlamp, remotes, bike lights, portable clock - anything that takes a AAA. I have bought Amazon Basics LSD batteries in the past and while they are good, these definitely do last longer and you get potentially 2,100 charges as compared to Amazon basics 1,000. In the long run they are worth the few extra bucks.I charge mine with a LaCrosse charger and usually use the 350 mA charge current (Anything below 750mA is safe for these)