What's Going On With These Batteries?

[CapnCrunch]

My batteries don't seem to be charging fully lately and, when looking at them, I noticed that several had slightly corroded connections. I decided to clean all the terminals and do a little testing while I was at it. Before doing any of that, I shut off all DC appliances, etc.

My process was to shut off the chargers (solar and AC), isolate all 5 batteries, clean all cables and posts, check voltage on each battery, then reconnect them all and again check the voltage on each. Here's what I got. (voltages are isolated/connected)

Battery A - 12.84/12.72
B - 12.87/12.68
C - 12.84/12.92
D - 12.82/12.89
E - 12.87/12.90

To make matters more confusing, my BMV 702 reads 12.63 after all the cleaning. Is this odd or am I nit-picking?