  We investigate the thermodynamics of dyonic hairy black holes in flat
spacetime when the asymptotic value of the scalar field is not fixed. We use
the quasilocal formalism of Brown and York and corresponding boundary terms
that make the variational principle well defined to prove that the scalar
charges do not contribute to the first law of thermodynamics. We also provide a
unified picture of obtaining exact solutions by comparing two different methods
and discuss in detail the ansatz used in each coordinate system and the
relation between them.
