A battery charger for vehicles comprises one outer container, one electronic appliance housed inside the container, operatively connectable to an electric battery of a vehicle and configured for the recharge of the battery, and one cooling circuit of the electronic appliance, wherein the electronic appliance comprises one electronic board provided with an insulated metal substrate associated with the cooling circuit, with a layer of electrically insulating material made on one portion of the insulated metal substrate, and with one electronic circuit made on the layer of electrically insulating material, in which the electronic board comprises one conductive metal bar for the transport and the distribution of current, electrically connected to the electronic circuit and provided with one portion arranged in direct contact with one surface portion of the electronic board, for the cooling of the conductive metal bar by the cooling circuit.