Another thing that's been nagging at me is the fact that my PakTrakr system fritzes out during part of the charging cycle. The 6th battery's voltage in each remote drops to 4 volts at the peak charging voltage, so it's forever saying that "Battery 6 is failing." Manually checking the voltage of that 6th battery showed that it was approximately the same as the other batteries, just over 16 volts.
According to Ken Hall at KJH Motor Company (maker of the PakTrakr system), the remote is designed to be limited to 90 volts (although mine clearly were limited to 86-87 volts). That means the remote can only measure the 36 cells (6 12V batteries that have 6 cells each) up to 2.5 V/cell. AGM and Gel lead acid batteries are charged at up to 2.45 and 2.4 volts respectively, so the remote can (barely) monitor 6 of those types of batteries. Flooded lead acid batteries are charged up to 2.7 V/cell, beyond the capability of the remote. Fortunately he also told me that there's no problem monitoring 5 batteries per remote (it will not mess up the display or serial logger). Since I have 13 batteries I already had 3 remotes, so I'll be able to use a 5-5-3 monitoring scheme and eliminate the out-of-range problem.
Unfortunately, I killed my third remote (the one that was monitoring the 13th battery). Apparently, one of the unused leads contacted another battery terminal while I was reinstalling it after some battery maintenance that burned out something inside it. I've sent it back - hopefully it can be repaired... Until then I'll be limited to monitoring 10 of my batteries.