I have a 2006 MacBook. On the second battery, and it lasts all day. What you should regularly do, is take apart the case, and use an aerosol spray can to clean out the dust bunnies. I bet your fan is clogged and allows your system to overheat, running down your battery. It's amazing how dust can build up inside over a period of months, let alone years. I just upgraded to a 2016 MacBook Pro. Not because the old one is no good, it is still going strong. I wanted to newer OS and faster speed of the new ones.
thanks roadcat! I’ll do that tomorrow! Mine does run hot.