Впрочем, главную проблему — быстрог

Впрочем, главную проблему — быстрого разряда батареи — никто из производителей пока не сумел решить, большинство смартфонов по-прежнему приходится заряжать каждую ночь.

Результаты (английский) 1:

However, the main problem is rapid battery discharge — none of the manufacturers have not yet managed to solve, most smartphones still have to charge every night.

Результаты (английский) 2:

However, the main problem - quick battery discharge - none of the manufacturers has not yet managed to resolve the majority of smartphones still have to charge every night.

Результаты (английский) 3:

however, the main problem is the rapid discharge of battery - none of the manufacturers still unable to decide most smartphones still have to load every night.