  We provide an architecture for a multimode quantum battery (QB) based on the
framework of continuous variable (CV) systems. We examine the performance of
the battery by using a generic class of multimode initial states whose
parameters can be tuned to produce separable as well as entangled states and
that can be charged locally as well as globally by Gaussian unitary operations.
Analytical calculations show that a separable state is equally advantageous as
an entangled one for two- and three-mode batteries when taking the figures of
merit as the second moments of the change in energy. In order to produce a
stable quantum battery consisting of an arbitrary number of modes, we derive
compact analytical forms of the energy fluctuations and prove that for a
multimode separable Gaussian initial state, fluctuations decrease as the number
of modes increases, thereby obtaining a scaling analysis. Moreover, we
demonstrate that local displacement as a charger is better to minimize the
fluctuations in energy than that involving the squeezing unitary operation.
