Hi Tango,
forgot one thing.
Each of the six (6) cells (nominal 2,0V) may be considered as faulty.
If that happens (and it happens sometimes!) the nominal voltage is reduced to 10 V. After charging with external charger was done, this defective cell is not charged and the reading of battery voltage would be only 5x 2,27V = 11,3 V. Measured right after charging, but charger disconnected.
Ok, measuring battery voltage right after charging is a dynamic process over some time, but battery voltage should be stable after some time (several minutes, max. one hour)
Please let me know 😉
Cheers, Michael
