I purchased 20V MAX LITHIUM TRIMMER/EDGER Model #LST220 on 26 Feb 2012. I didn't use it until about mid April & charged the batteries the day before use until the charger light was a steady green. I have a small yard and read in the manual the battery was supposed to last about 4 hrs. I would get several uses out of one battery, it only lasted about 20 minutes. I was able to finish my yard with the second battery. Neither one seems to hold a charge even straight from the charger.I really like the trimmer! How do I get the batteries replaced?