My Accord was becoming more sluggish when starting. Had the battery and charging system checked at AA. The only fault the test found was the battery could use a good charge. I cleaned the posts and cables and connected up the charger. 10 hours later the "charged" light still was not on. I did this to my Pilot this past summer and the light did come on. Battery is 5 years old, but I am told these can last 7-9 years here in the upper midwest. What are some reasons a battery would not fully charge, or might it take 15-20 hours to fully charge?