I got a Dewalt pack off EBay for about $90. It has 10 cells in it and is pretty easy to take apart. To use you existing chargers, get a 'Dapter from http://www.slkelectronics.com/lipodapter/index.htm. If you are using a 3S 3 cell pack, you can use a 12V battery connected to the cells with several feet of lamp cord. The lamp cord keeps the current down and the cells can be safely charged to 4V.