Motors and generators tend to be way more 65% efficient. Random internet search mentions 70-98%. If they were not, pumped hydro would not be useful either. Lin

Motors and generators tend to be way more 65% efficient. Random internet search mentions 70-98%. If they were not, pumped hydro would not be useful either. Linked article is short on details, but the link wiredfool gave has more details including a video with numbers (2nd video 02:00). They claim >93% (Combined M&E) one-way efficiency. I don't know what one-way is, but 0.93^2 = 86%, which would make the loss noticeable, but I would still consider it good enough for storing solar/wind.