These “Fujitsu” rechargeable AA batteries are the REAL eneloop batteries, and they always have been.
True “eneloop” batteries were - and still are - manufactured by the Twicell factory in Gunma, Takasaki, Japan. The Twicell factory is currently owned by “FDK” Japan. Twicell was owned by Sanyo when they produced the “eneloops” for Sanyo, which in turn packaged them as “Sanyo eneloop” batteries.
Panasonic is a multi-national corporation based in Japan, but which does much of its manufacturing in China. In December 2009, Panasonic acquired Sanyo. Panasonic then began manufacturing its own version of “eneloop” batteries that were made in China. This resulted in some adverse changes to the traditional “eneloop” AA batteries.
When Panasonic bought Sanyo, part of the deal with the Japanese government was that the Twicell factory had to be sold off, and remain under Japanese-manufacturing control, and that all the patents, technicians and technology that produced the original “eneloop” batteries at the Twicell factory had to remain with Japan. You can still buy that same (and now updated) technology today in these Japanese “Fujitsu” AA rechargeable batteries - made by the same Twicell factory, just as they always have been.
Furthermore, by Japanese law, all “Panasonic eneloop” batteries sold in Japan today must be made by the Twicell factory (and marked “Made in Japan.”) The European Union has a similar restriction. Unfortunately for American consumers, the USA does not - both kinds are sold here.
BEWARE of any “good deals” you may see on “eneloop” batteries, … and here’s why.
In the USA today, the “eneloop” batteries are sold two ways - Made in CHINA, and Made in JAPAN. The “eneloop” batteries marked “Made in China” are not using the same technology as the “eneloop” batteries marked “Made in Japan.”
Panasonic is using work-around technology to imitate the Twicell “eneloop” technology, in order to sell their Chinese-made “Panasonic eneloop” batteries on the international market.
Chinese-made “eneloop” batteries are supposedly produced at Panasonic’s Wuxi factory in China, but there is strong suspicion that they are actually re-badged Evolta batteries, and use inferior technology.
Based on at least one Japanese study I found, the Chinese-made “eneloops” start out well, but begin to lose a substantial amount of their charge-holding ability after only about 20 recharge cycles. As far as I can tell, this report is only available in Japanese, but with the help of a Google translator, I was able to read a substantial portion of it, and the accompanying charts were also very helpful. Test results were very clear. After 20 recharge cycles, Twicell factory “Fujitsu” rechargeable AA batteries still maintained their charge-holding ability very well. “Made in China” Panasonic eneloop AA batteries didn’t.
Furthermore, a thriving market is booming in the USA for counterfeit “Made in Japan” eneloop batteries. … These items are counterfeits! They are not genuine “Made in Japan” eneloops. Who even knows where they are made? Or how well they are made? Some websites can show you examples of these counterfeit markings - just Google “counterfeit eneloop batteries.”
But the safest thing to do is simply to buy “Fujitsu” AA rechargeable batteries, marked “Made in Japan,” which do use the original (and now updated) Twicell-factory “eneloop” technology. That is what I have now switched to doing myself. To my knowledge at least at this point (Feb. 2015,) there are no known, widely-distributed counterfeits of the Fujitsu AA batteries.