Google 'Arduino Bench Power Supply'. You will find that a device to do what you are asking is going to be rather complex. Depending on your skill level, you may be better off looking for a commercially available solution.
Off the shelf bench power supplies in the order of a few amps can be had at a fairly reasonable price. Higher currents become expensive. I am assuming the higher current is required for battery charging, which also can be achieved with a hobby charger such as an iCharger or one of its clones.