I found a couple of other screens on the display you can access during charging by holding down the "mode" and "trip" button together.
The first screen shows 3 lines of information along with the normal battery %, time, odometer, etc. The first line is the highest and lowest cell voltage readout along with which cell pair number it is in the pack. The second line reads out the pack voltage, charging current and state of charge in %. The third line marked "Bal" followed by 14 dots shows the operation of the balancers. If the battery is balanced just the dots are shown. If the battery is actively balancing there will be a letter "A" shown. When I first got the bike, there were a lot of "A"'s turned on during the first full charge, now not so many.
If you hold the trip button in for a few seconds, you will toggle to a second screen. The first line of this screen reads the battery voltage and current just like in the prior screen. The next line has three numbers proceeded by Tp, Ts, and Js. These numbers change during the charging session but I have know idea what they mean. The final line reads Err: and then (in my case) 00 00 00 followed by S:2. Again know idea but could be a error log of some sort. Pushing the trip button will toggle you back to the first screen so there are only two total.
Kind of neat to find this sort of stuff. Fun to look at but not useful for most people but good to know if you want a little more detail about your battery health. BTW--the amount of voltage change between the highest and lowest cell can really affect the range of the bike. Balancing only occurs during the final segment of the charge cycle when the charge current is low. That's why it is important to fully charge the bike once in a while so the balancers can do their job.