Batteries DO NOT “wear out” one cell at a time…With a 2004, 6 or 7 years old, the entire battery pack is nearing the end of its service life. Installing new cells in an old battery is a waste of time and money…
If you can’t afford to replace the entire pack, locate a USED pack or group of cells from a car of similar age and mileage and used THOSE cells to “rebuild” your failing battery pack…