Can the Alembic Activator pickup system be run safely be run at 18 volts?
I don't know the answer to your question. But until someone comes along who does, here's a couple of threads that touch on the subject. Might help a little.
https://club.alembicguitars.com/Images/449/5324.html (https://club.alembicguitars.com/index.php?topic=21046)
https://club.alembicguitars.com/Images/402/2872.html (https://club.alembicguitars.com/index.php?topic=6867)