We compute the renormalized expectation values of the scalar condensate, charge current and stress-energy tensor for a massive charged quantum scalar field on a Reissner-Nordstrom black hole. The mass of the scalar field is sufficiently large that classical superradiance is absent. We present results for the Boulware, Unruh and Hartle-Hawking states. Renormalized expectation values in the Hartle-Hawking state are computed using an efficient and accurate mode sum prescription, and for the other two states we employ state subtraction. The efficiency of our numerical method enables us to explore a large part of the parameter space, including near-extremal black hole charges and scalar field masses close to the superradiant limit.