If you own a Harley Davidson or are contemplating buying one, you should know that it needs a battery with a CCA (cold cranking amps) of at least 300. Most aftermarket Harley batteries come with a CCA value greater than 300, making them reliable in any weather conditions. You can install a battery with a CCA value of less than 300 without any worry. The only drawback will be that you will not be able to enjoy the full potential of a Harley.