Sanyo introduced eneloops in 2005 with the code HR-3UTG. The second generation was given the code: HR-3UTGA (with the added A). The 3rd generation was named: HR-3UTGB with the added B.
From the 4th generation, Panasonic changed the code to BK-3MCC for the enloop basic AA in Japan, BK-3MCCE for Europe, and BK-3MCCA for North America. (the added letter E and A are not coded for a different generation as sanyo used to do, but merely a designed code used for which market they are sold at.)
By their appearance you can see the differences in the following:
- 1st generations didn't have a picture symbol of a Crown
- 2nd generations has a crown toward the positive side
- 3rd generation has metallic shiny letters, and a Line underneath the Crown image
- 4th generation for the worldwide market has the text Panasonic corporation above the blue PLUS (positive) sign in small font
The top picture shows a 1st, 2nd and 3rd generation eneloop batteries for the Japanese market, and the 4th generation eneloop for the European market. The 4th gen is coded BK-3MCCE. While the US market has the code BK-3MCCA for the same battery.
Keep in mind that the latest upgraded 4th generation now have specs saying 70% capacity left after 10 years, while the original 4th generation had 70% after 5 years.
The Japanese market had a make-over in 2013 and replaced the blue printed name eneloop with Panasonic, and eneloop underneath it in small font, as can be seen in the 2nd picture. I prefer the bottom one, of course.
Why do we call them 1st, 2nd, 3rd and 4th generation eneloops?
During the years Sanyo produced eneloop batteries, they started to improve their batteries over time. When they retested the batteries and showed an increase in quality as in amount of cycles they could do, they changed the product code.
The 2nd generation AA were called HR-3UTGA. So we, as consumers, used these specs of increased capacity or increased charge cycles as a new generation in combination with the new coding.
2-3 generation at a time.
This does not mean that when a new generation was announced, they stopped producing the previous generation. I believe, and my little research confirmed this that they AT least produce 2 (maybe even 3) generations at the same time. Let me explain this:
In 2013 , (when I still lived in Japan), I followed the change of the make-over that Panasonic did in the Japanese market closely. At the same time overseas seller were selling eneloop batteries from a previous generation BUT with the same production date. This confirmed my understanding of the whole generation thing not being an AGE/Production year thing, but a quality thing.
From 2013 Panasonic decided to change the labeling and coding of their batteries, which resulted in completely new codes. BK-3MCC for the AA standard model. (BK-3MCCA for the American market, and BK-3MCCE for the European market), so now the additional letter A was not a change of generation anymore.
Plus the product code BK-3MCCE is also used for the batteries that are made in China, for the Oceania market.
The confusion in 2015 was when Panasonic changed the specs of their standard eneloops, but did not change the coding of the batteries.
They remained being coded BK-3MCC (with or without the added E or A for different markets). But they showed a 70% capacity remaining after 10 years, in stead of the 70% after 5 years.
And the Chinese made batteries since then show a 70% left after 5 yeras, so it can be pretty confusing for certain markets. They used to label them 65% for 5 years!
Is there a 5th generation standard eneloop?
No, or maybe Yes.
If you look closer to these updates, it can be noted that the difference is not clearly in the specs but in the kind of testing according to newer standards. The first 4th generation eneloops were tested according to the standard: JIS C 8708 2007 (126.96.36.199) and showed 2100 cycles , 70% left after 5 years, while the standard eneloops tested in 2015 used a different standard: JIS C8708 2013 (7.3.2). This was confirmed by a EU Panasonic employee. So my understanding is that these are actually the same batteries but tested by different standards.
Btw: JIS stands for: Japanese Industrial Standards.
There are sellers who sell 5th generation eneloops, and although I myself used to call them that way, I stopped doing this after I noted these details as well as the reply I got from the Panasonic employee.
Is there a 5th generation Eneloop PRO?
Now, if you look closely to my complete eneloop lineup you can see that I called the eneloop XX/PRO HR-3UWXA a 2nd generation battery, but this was actually the same battery as the HR-3UWX which was being sold worldwide. The 3UWXA was only sold in a certain market in Asia.
To keep the consistency of generations, I had to call them a different generation, otherwise things would be really confusing. Therefore the PRO version is actually 1 generation ahead of the standard ones at this time of writing, March 2017. With their latest version now being the BK-3HCD (E/A)
There had been some confusion about the little venting holes that can be found on certain generation batteries.
Since the first generation Eneloop had 4 venting holes at the Positive side of the battery.
They continued this with their 2nd generation in 2009, until November 2010, when they started to ship them without visible venting holes for standard AA eneloops.
See the pictures of a 2nd generation standard eneloops HR-3UTGA with venting holes. 2nd generation were made with and without visible venting holes.