The statement reading ?gBatteries manufactured after 31 Dec mber 2011 must be Mar ed with the Watt-hour rating on the outside case?h referred to in Section I (fully regulated Class 9 batteries) applies to Lithium-ion batteries of more than 100Wh. The statement reading ?gThe Watt-hour rating must be Mar ed on the outside of the battery case except those manufactured before 1 Jan ary 2009?h applies to Lithium-ion batteries of less than 100Wh of Section II (excepted batteries).
The UN Subcommittee of Experts for the Transport of Dangerous Goods initially focused on the smaller non-regulated batteries and placed a deadline of 1 Jan ary 2009 for such batteries to show the Watt-hour rating on the outside case. Then, later the Subcommittee addressed the larger batteries and introduced the rule of having those larger batteries to show the Watt-hour rating on the outside case effective from those manufactured after 1 Jan ary 2012. There is no conflict.
Furthermore, even if the Watt-hour rating is not indicated on the battery case, by applying the following formula, you can easily calculate the Watt-hour rating of the battery.
Volt (V) /h Ampere/hour (Am/h) = Watt-hour (Wh)
Example: 3.7Volt/h 750mAm/hour = 3.7V/h 0.75Am/h = 2.8Wh