Make homemade lemonade with enough sugar to sweeten to taste but not sticky sweet. Add 1/2 tsp Morton Lite Salt (half sodium chloride, half potassium chloride) per liter/quart.

You can do the same thing with green tea or any other sugar sweetened drink or diluted fruit juices that bring their own sugars to the party.

There is nothing mystical about the properties of sports drinks. They provide simple carbohydrates or complex carbs that break down very rapidly into simple carbs (ie. maltodextrin) and a blend of electrolytes. The "energy" drinks add some form of stimulant to the mix to give it a little kick. Some add assorted B vitamins but there are plenty of other ways to get your vitamins.