This presentation describes GPU (graphics processing unit) accelerated mixed precision algebraic multigrid preconditioners for discrete elliptic field problems. The use of a mixed-precision implementation of Krylov subspace methods with multigrid preconditioners is proposed for solving the large linear systems stemming from finite-element or finite-difference method discretizations of elliptic problems as they occur e.g. in electrostatics. The computational limits in speed and memory are discussed using the numerical example of a large-scale 3D high-voltage isolator model.