The motor vehicles often ran out of charge and had to be towed back again to the depot, as well as the small-slung battery packs often became submerged in water-filled potholes throughout monsoons. "Tencent Prospects $820 Million Financial investment in Robot-Maker Ubtech - Caixin Worldwide". . Retrieved 26 June 2021. ^ a b c d e f g h i j k l m