Sorry if I am in the wrong area.
Very simple I think.
I have a friend that has an Elf. It has a Nominal 48V 10AH pack built with Headway E 38120 Cells
The pack is a 16S 1 P with a bms.
Issue 1 he let the pack drain to a total pack voltage of 8.7V
Fast charger (15 amp) would not even crank up it...