If you take a look at the graphs, you can see that battery 20 (guity number) or 5 (cell logger number) takes a dive at every opportunity, much lower than every battery. The biggest dive came while coming back up the hill today, but you can see there were other dives probably corresopnding with every time I accelerated hard from a stop. You can also see that battery 24 (cell logger's 1) and 18 (cell logger's 7) sucked as well, though not as bad. I guess it is a bit too early to jump to conclusions until I have logged the other 16 batteries as well...
But interestingly enough, you can also see that all the bad batteries, even the worst, comes back up even with the others when there isn't a heavy load. Hence, by the time I got the bike stopped and checked the voltages, none of the batteries looked all that bad...