Battery Date Codes
Some batteries have a date code printed or stamped into their labels. Do not use codes stamped onto the packaging for the batteries, but the code stamped directly on the battery.
Sanyo and Eneloops
6 character code: yy-mmxx where yy is the year (09 for 2009) and mm is the month (01 for January, 02 for February). xx is alphanumeric (not sure what it means).
6 character code: ym dd-xx where y is the year (9 for 2009) and m is for the month (A is January, B is for February), dd is two numbers for the date and xx are letters (not sure what they mean).
4 characters code: myd-x where m and y are the month and year (see below) and d is a letter representing the date (A=1, B=2, ... Z=26, 2=27, 3=28, etc.). x represents the origin with O being USA, J, S, and Y being China, and R being Malaysia (9V alkaline).
1st character is the month, 2nd is the year:
R Jan Y 2007 A Feb P 2008 Y Mar B 2009 O Apr G 2010 L May W 2011 I Jun T Jul E Aug S Sep H Oct U Nov M Dec