  We study odd dimensional charged equally rotating black holes in the
Einstein-Maxwell theory with/without a cosmological constant by using the large
D expansion method, where D is a spacetime dimension. Solving the
Einstein-Maxwell equations in the 1/D expansion we obtain the large D effective
equations for charged equally rotating black holes. The effective equations
describe the nonlinear dynamics of charged equally rotating black holes.
Especially the perturbation analysis of the effective equations gives analytic
formula for quasinormal mode frequencies, and we can show charged equally
rotating black holes have instabilities. As one interesting feature of
instabilities, we observe that the ultraspinning instability of neutral equally
rotating black holes in de Sitter is connected with the instability of de
Sitter Reissner-Nordstrom black hole in a rotation-charge plane of the solution
parameter space. So these instabilities have same origin as dynamical
properties of charged rotating black holes. We also give perturbation analysis
by a small charge for even dimensional equally rotating black holes.
