score:7
FAA FAQ (lithium regulations are same everywhere):
The main limit is that the batteries and devices must be for personal use (includes professional use). Batteries and battery-powered devices carried for resale or for distribution by a vendor do not qualify for these exceptions. There is a two-spare limit on the large lithium-ion (101-160 Wh) and nonspillable batteries.
Quantity limits: None for most batteries – but batteries must be for use by the passenger.
Security wise there's no limitation. My record so far has been three laptops, two phones, a tablet and an eReader, at Canadian, USA, UK and several Schengen airports. Noone gave a hoot.
Your only possible problem could be customs but you are intra Schengen so no such problems exist.
Edit: despite there is no customs, security might ask whether you plan to sell them because of the battery rule above. Have a simple, true explanation ready.
Upvote:3
The company I work for does conference management and we often send staff onsite. As they usually use a few laptops for registration and paper upload work most of them have 2-3 laptops in their hand luggage. Flown to the US, Dubai, Turkey, all over the EU with laptops in hand luggage and normal luggage. No-one ever had a problem.
I once entered the US with a suitcase full of electronics (router, switches, cables, 3 laptops, small printers, print server, a few tablets, a small NUC computer) and flew back. Not a peep from any customs.
Ok, the laptops are obviously battered and used and we can show that we work onsite at a convention so obviously they are not for resale, but no-one has actually asked.