When the batteries where installed last week, they had never
been balanced and when a full charging current (80A) was applied this week, one of the cells went to 3.8V while others were still down at 3.4V. The LED on the cell board of the 3.8V cell began flashing an error condition and if I had a BMS, the contactor would have tripped and disconnected the batteries. The installer advised balancing the cells which was accomplished by slowly upping the charger
voltage to 14.8V (3.7 V/cell) until all the cell boards were shunting and the voltage on each one was 3.7V (well, one stayed at 3.6V). The cell boards can "burn off" 1.5A each via their attached resistors which did get hot during the balancing process. This is not enough "burn off" however to stop a cell going over voltage if they are unbalanced and a high charging current is being applied.
As Doug says, very little shunting has occurred on subsequent charges now that the cells are balanced.
I guess one issue to come to consider if one had a BMS managing a contactor is that an event such as the above could result in losing all power at critical juncture such as entering a pass or during a critical radio
call. A BMS audio alarm
but with a contactor override capability may be the ideal.