I've noticed in each of the available app variants the voltage displayed for individual cells can vary from app to app. All of them are different than my multimeter, which I trust. Overkill's pdf talks about calibrating cell voltages and even shows a screen to do so, but I can't find any way...
Mine are consistently off by around 5 mV, across the board. One of the cells may a little more, one may be a little less. I suppose I'll just make up the difference in my head over time, but I thought it might be nice to true it up in an attempt to be true to my anal retentive nature. :oops...