There are a variety of variables that you need to consider when determining the average life-span of a motorcycle battery. AGM lead acid batteries will not last as long as some of the newer lithium batteries. Most lead acid AGM batteries have a 4 year service life span. If you live in a cold climate and do not maintain your battery during the winter months you will greatly reduce the life span of your battery. This applies to Conventional, AGM, and Lithium batteries. During those winter months it is a good practice to keep those batteries charged and in a warm storage area.