According to this US Government site, spare batteries should be packed in carry-on luggage only. Here is the table that appears on the official website. GUIDE TO RULES EFFECTIVE JANUARY 1, 2008 Type Of Battery/Batteries In Checked Baggage In Carry-On...
The basis for all of this nonsensical conclusion is apparently some unsubstantiated leap between mobile phone technology and equipment and a theorized similarity to WiFi equipment. Say what? Someone at Panorama is WiFi phobic. My long standing opinion...