I don’t think that works. They will see things via x-rays I guess and then you have no excuse for your action. I rather would take them inside your carry-on bag for your “personal use”. Make sure that you don’t have more than you could explain. “My Linux phone consumes up to 6 full charges a day, so I always carry 5 batteries on travel where I cannot charge over the day” could be a good explanation. The “personal use” is the limit, but without a specific number. So it depends in first hand how you can explain it. In best case bookmark a forum page where people speaking about battery drain within 4 hours or so to prove you’re right.
Here an information link. Make sure that you read it carefully (for example how to carry them “protected”).
Also think about how to handle payment with people. It would be better to do in Euro since there is no exchange and you can use it directly on your vacation. But it will be hard to do it since people are maybe thousands of kilometer away. However, I would be interested in one battery (but first I need to know how to pay before I finally say “yes”).
Cool move btw.
