All of my five 36v e-bike batteries (2 x Fiido, 2 x Phylion*, 1 x TranzX*) continue to draw (typically) 18w once the charger LED turns green. It takes another 0.5 to 1 hour before current draw drops below 3w, which is, I'd assume, when balancing has actually stopped?
*These too are Sans chargers.