Charging of electric vehicle in an uncontrolled manner can seriously impact the power distribution grid and make the large scale adoption of electric mobility non viable. In this paper we propose an online charging discharging decision sequence for electric vehicles in a commercial charging station to minimize the overall cost of charging the electric vehicles while satisfying the number of constraints. The control problem has been formulated as a multi-objective optimization problem, which aims to reduce the cost of charging the electric vehicles, reducing the frequent change in charging rates, flattening the load profile subject to equality and inequality constrains of the chargers and the grid. The decision sequence is capable of handling both the homogeneous as well as heterogeneous charging requirements with random arrival times and deadlines. The problem is transformed to a convex optimization problem which can be solved using any standard convex optimization toolbox. We empirically demonstrate that our proposed decision reduces the cost of charging and frequent changes in charging rates while reducing the peak loading on the grid.