  Energy storage is a basic physical process with many applications. When
considering this task at the quantum scale, it becomes important to optimise
the non-equilibrium dynamics of energy transfer to the storage device or
battery. Here, we tackle this problem using the methods of quantum feedback
control. Specifically, we study the deposition of energy into a quantum battery
via an auxiliary charger. The latter is a driven-dissipative two-level system
subjected to a homodyne measurement whose output signal is fed back linearly
into the driving field amplitude. We explore two different control strategies,
aiming to stabilise either populations or quantum coherences in the state of
the charger. In both cases, linear feedback is shown to counteract the
randomising influence of environmental noise and allow for stable and effective
battery charging. We analyse the effect of realistic control imprecisions,
demonstrating that this good performance survives inefficient measurements and
small feedback delays. Our results highlight the potential of continuous
feedback for the control of energetic quantities in the quantum regime.
