NFC problem on Galaxy Nexus

Spent a number of hours and tried lots of apps in my search for reason why it didn't react at all. Then I remembered some connection with batteries, and realized I might have a defect (or fake) spare battery.. YES! that was it.

Swapped back what must have been the original battery and everything works OK.

Have more 1KB NFC stickers on the way which will give me more scope for experiment. The Sony Xperia Smart Tags are only 48byte capacity..