Yes, it is time consuming. Each cell takes about 18 hours. In total I have purchased 16 "grade B" cells and 32 "grade A" cells. I have tested them all multiple times, using multiple testers. The factory rejects averaging 273ah, with the two lowest being 264ah, and 2 reaching the 280ah capacity. Every one of the grade A cells were 290ah or above. With my admittedly small sample size, I recommend buying extra cells to prevent the lowest cells from limiting the capacity of your battery bank. You still get more bang for your buck than the grade A cells.