I've also started lifting a heavy object (goal zero lithium Yeit battery) up to twenty times in each occasion by bending the elbow to lift to under chin, then held down - arms straight. (not sure of the terminology). My work hours are varied, so I can't get into a set routine each day.
That sounds like you are describing "bicept curls" Maybe you are describing "hammer curls" from this article?
https://www.mensjournal.com/health-fitness/10-different-ways-do-curlYeh Hammer curls looks to be it, but I'm holding the object in both hands due to its size and weight, but its up to the chin and back down with arms strait.
I've done two sets of fifteen to get my count for the day underway. I'll give an updated figure later on.