Customer Reviews

Sony Cycle Energy 2000 mAh Pre-Charged AA Rechargeable Batteries

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The Sony Cycle Energy 2000 mAh Pre-Charged AA Rechargeable Batteries are low-self-discharge NiMH type, similar to the more well-known SANYO eneloop. Even their marketing claims sounded almost identical, such as:
- 'Stays 85% charged after 1 year of storage'
- 'Recharge up to 1000 times' (2nd-gen eneloop cells actually claim to achieve 1500 cycles)
- 'Battery Capacity: 2000 mAh'

Naturally, this leads to speculation that SONY Cycle Energy is just Sanyo eneloop under a different wrapper. But apparently it is not the case, based on the following observations:

1. There are minor differences in shapes of positive and negative terminals between those two brands. (See my Customer Images uploaded, and judge for yourself)
2. SONY Cycle Energy cells are made in China, while Sanyo eneloop cells are only manufactured in Japan.

Of course, the real important question is: Do SONY Cycle Energy cells perform just as well as Sanyo eneloop cells? The answer is YES - based on my own test data so far.

I have tested a set of those SONY Cycle Energy AA cells, using my La Crosse BC-900. Here are my findings:
- Right out the box, the average remaining charge in those cells is 1431mAh, or about 70% of rated capacity
- After the first recharge, their average capacity improved to 2032mAh
- After one more recharge/discharge cycle, the average further improved to 2082mAh

Date code imprinted on those SONY cells is '1005', which I interpret as 'May 2010'. That means they were manufactured 7 months ago. Note that similar to eneloop cells, those SONY cells were probably not charged to 100% when they left factory. That explains why they arrived with only 70% of full capacity.

Also note that on each SONY cell it says 'typ 2100mAh, min 2000mAh', while Sanyo cell says 'typ 2000mAh, min 1900mAh'. But in my experience, the measured average capacity of eneloop cells is actually around 2080mAh

So my conclusion is: The electrical characteristics of those SONY cells are practically indistinguishable from that of Sanyo eneloop. Therefore just pick whichever brand is on sale, and you can't go wrong.

[Update on Feb 14, 2011]
Do not confuse this product with the newly introduced Sony Cycle Energy NHAAB4RN 1000 mAh AA Pre-Charged Batteries. The latter is currently priced at about 25% less, but its capacity is 50% lower!

I am an electrical engineer, and I have tested many, many batteries. The Sony CycleEnery batteries are the best batteries in the world. No other battery has performed as well for me. I highly recommend this battery above all others.

There are two things that make the Sony CycleEnery battery perform so well:

First, if you weigh the Sony battery on a scale, you will find that they are several grams heavier than any of the other brands. This means that there is more material inside, which yields a higher battery life span.

Second, the voltage curve of this battery stays above 1.2 Volts throughout the majority of its life span. The reason this is important is that most electronic devices, such as digital cameras, stop working once the voltage goes below 1.1 Volts. Normal NiMH batteries can have extremely high mAh ratings of 2500 or more -- but you can't actually make use of all those mAh's because the voltage drops below 1.1V relatively early -- this is not the case with the CycleEnergy. Sony has done something to keep the voltage up at 1.2V, so even though the battery is only rated at 2000mAh, they last much, much longer than normal NiMH batteries. I usually get 2-4x the life span out of CycleEnergy batteries, compared to normal NiMH (even the Sony ones!).

To summarize -- these are the best rechargeable batteries on the market right now (2008).

Regards,

~Chris Sebastian

I bought two sets of AA and one AAA of these Sony Cycle Energy batteries from a large NY-based and internet camera store during an 8 USD/AA 4-pack deal was posted on slickdeals a couple of weeks ago and I wanted to relay my experience. (Though I do buy most everything else at Amazon!)

All of the batteries were made in China as per prior posts. They all came out of the package with decent voltage (1.3v? I don't recall exactly) but at maybe 50% of the rated charge of 2000 mAH. I personally don't much care since I was going to charge before using anyway. I had encountered a significant variation with 4 of the 8 AA batteries -- 3 from one pack and one from the other pack.

I use the La Crosse BC-700. I did a simple charge of all of the batteries first. That did not bring the charge up near the rated level. On the first 4, I did a single full discharge-charge cycle and they went up as high as almost 2400mAH! Great! The other 4 did not fare as well. A discharge-charge cycle still did not get them up to 2000 mAH, though mostly in the ballpark. I then did a full "refresh" (repeating discharge/charge cycles until no improvement) and 2 made it to 2030 mAH, while the other 2 only 1970mAH.

SUMMARY:
With discharges and refreshes, all of the brand new Sony's were able to get within an acceptable tolerance +/- of the rated charge and some went far beyond the rating. My main point being that not all of these Sony's are created equal. I'm still using a set of Eneloops for my SLR flash, but these are just fine for wireless mice, WiiMotes, toys, and the like.

I got this set in addition to Sony 2500 mAh AA Rechargeable Nimh Batteries. This set seems to work better than Sony 2500mAh batteries.

After trying nearly every rechargeable battery and being disappointed that they did not arrive pre-charged as claimed, the Sony Cycle Energy batteries arrived ready to go, just as claimed. The higher price and lower mAh were a matter of concern for me before I ordered. Sony has 2500 mAh for less here on Amazon, but careful reading of the customer reviews led me to this choice and so far I'm very pleased. One surprise was to read the fine print (and I do mean fine) on the battery back and discover that these are based on eneloop technology. I could have bought the eneloops for less and that had been my first choice until I read the reviews. I suppose the hybrid technology is driving all the brands I tried, but Sony is the first to deliver on the promise. Sony Cycle Energy AA Ni-MH Rechargeable Batteries (4-Pack)

They really last a lot. Other batteries that I have do not hold charge for a long period.

The batteries are the best ones I have! I own two other sets DURACELL 2650mah, one of them is a very good set, keeps charge for a month; the other loses it for a few days. Had other brands before, much worse! So these batteries last for VERY long time; would say- months without recharging. This new technology is really good; I will not buy the old NIMH anymore. As of my knowledge, all these new stile batteries are made by SANYO, for all other brands, what is good, because Sanyo is the biggest and best battery maker. Very Happy, highly recommended!

I was used to have the batteries that came with the charger, those batteries would last around one week charged after a full charge, this ones instead come with a full charge, and it doesn't go away after a month without using them.

Amazing

I have a digital camera that runs on AA and I need to keep a lot on hand to change out often. With these batteries I am swapping batteries much less often as they seem to hold a charge much longer. Very satisfied.

I use quite a few Eneloop low-self-discharge batteries: AAs in my Canon S5 IS and some toys, AAAs in Harmony 659 and Dish remotes. I really like how these rechargeables keep the charge for very long time.

These Sony low-self-discharge batteries were on sale, and I decided to give them a try because of the price. In my opinion, they are just as good as Eneloops.