Take an ordinary extension cord, cut off the female end, strip the wires and connect them to the battery terminals, and then plug the male end into a wall outlet. It should work perfectly. Make sure someone is standing over the battery and looking at it very closely during this process.
My daughter needs to be able to do 40 pushups in under 2 minutes by the end of the month, but right now she can only do 5. What kind of training plan do you recommend?