I purchased a replacement battery last year, from Tool Nut for my C 12, as the drill is still in good shape. I only have the one battery for the C12, but I do have my CSX and the Festool Impact Driver. Having the C12 for use with the accessories works for me. I do not think you can get a 12 volt Li-Ion for the C12. I priced a 12 volt from Battery Plus but it was only a couple of dollars cheaper than Festool, and Festool had the longer Warrenty. Also using the accessories with the Impact Driver is rather awkward.