  We study the interior of black holes in the presence of charged scalar hair
of small amplitude $\epsilon$ on the event horizon and show their terminal
boundary is a crushing Kasner-like singularity. These spacetimes are
spherically symmetric, spatially homogeneous and they differ significantly from
the hairy black holes with uncharged matter previously studied in [M. Van de
Moortel, Violent nonlinear collapse inside charged hairy black holes,
arXiv:2109.10932] in that the electric field is dynamical. We prove that the
backreaction of charged matter on the electric field induces the following
phenomena, that ultimately impact upon the formation of the spacelike
singularity:
  - collapsed oscillations: oscillatory growth of the scalar hair, nonlinearly
induced by the collapse.
  - fluctuating collapse: the final Kasner exponents' dependency in $\epsilon$
is via an expression of the form $|\sin(\omega_0 \cdot \epsilon^{-2}+ O(\log
(\epsilon^{-1})))|$.
  - Kasner inversion: a transition from an unstable Kasner metric to a
different stable Kasner metric. The Kasner inversion occurring in our spacetime
is reminiscent of the celebrated BKL scenario in cosmology. We additionally
propose a construction indicating the relevance of the above phenomena -
including Kasner inversions - to spacelike singularities inside more general
black holes, beyond the hairy case. Our spacetime finally also corresponds to
the interior region of a holographic superconductor, which have been previously
studied in the high-energy physics literature.
