How do you charge the battery on a Harley?

Remove from the mc, disconnecting the ground cable first. Then hook up to a trickle charger at 10% the amp hour rating of the battery. Probably 2 amp. Charge fully, overnight is a good bet. Then load test the battery with an iron type load tester. Any auto parts store will usually do this for you at no charge. If it passes, reinstall battery in the mc reconnecting the ground cable LAST!! Then have fun riding. If the battery doesn't pass the load test, replace the battery new, and follow the previous charging procedure BEFORE you install into the bike. I dont care if it is "new" the battery had surely been sitting around waiting for you to come buy it. Recharge, install and ride away.