thanx CarnageX! about all i ever knew about lithium ion batteries is they were not supposed to take a set if you charged them incorrectly. in all actuality, the only real training i ever got on batteries in general was old school lead acid-batteries. as in the ones you actually had to check the electrolyte levels in once a month or so. maintenance free (lead-acid) batteries came along, and we were given a few tips and tricks at the new model one day seminars. and towards the tail end of my career, gel maintenance free batteries came along. the big thing about them was they could be mounted in any position, even up side down. i did see one or two of those before i was retired. but it was just new model prep. i have owned many rechargeable Ni-cad powered tools, and actually burned up one by way, way over working it. but i have not owned a lithium ion tool yet. but its time has come. its good to know something about the battery before i had a chance to ruin it.