started up my bike today and my engine and battery light came on. the voltage showed 12 on my instrument cluster. As I rode about 10 miles the voltage dropped to 11 then 10, the bike however ran fine. got home turned the bike off then tried to restart the bike.....barely turned over - did not start. waited 2 hours tried again, almost started. I am thinking bad battery but just wondering if it could be something ( voltage regular etc.) else before I pick up a new one. bike and battery are 2 years old.