Batteries are OK, Charger is a pain to deal with.
The batteries are fine and work as advertised.
The charger cannot charge a single battery.
The Bottom Line:
Once again the batteries work as I expected. The charger only charges exactly 2 or 4 batteries, which is annoying. Sanyo needs to redesign the charger.
Eneloop batteries are latest technology batteries from Sanyo Corp. It is claimed that they hold their charge longer than older technology batteries, and are sold fully charged as they do not lose as much charge in the time between manufacture and sale. I am not an expert on rechargeable batteries. What seems to me to be an expert opinion can be found here:
Review: Testing Sanyo's Eneloop Low Self-Discharge Rechargeable Battery
My opinion of the batteries: The batteries worked fine in my mouse. I have no complaints about the batteries. I would buy them again, and may have to due to the charger.
My (negative) opinion of the charger: The included charger is the one Sanyo recommends for use with the batteries it takes 4-7 hours to work. It is claimed it charges the batteries at the fastest rate consistent with prolonged battery life. The problem with it is that you have to charge 2 or 4 batteries together, or it will not work. This is very annoying as you have to keep track of which batteries are charged and which are not, and wait until you have exactly 2 or 4 discharged batteries to charge. Needless to say this is not pointed out clearly in the manual and is annoying as I have to discharge 2 batteries before I can recharge them. For example my Mag-lite flashlight uses 3 AAA batteries, once discharged I can recharge 2 but not all 3. This is crazy in my opinion.
Overall opinion: I rated the combination of batteries and charger as average. If the charger and its poorly written manual were better I would have rated it higher. I would not advise others to buy these batteries with the charger, you can buy the batteries seperately or rebranded as Apple among others.