Batteries are made up of cells connected in series/parallel to achieve the desired voltage and capacity. There are some crappy cells to be sure, but the interconnects are done with welded nickle straps and after a few bounces, they can break and connect things that shouldn’t be. All lithium chemistries require battery charge management (BCM) circuits and if the controller can’t tell what’s happening in a particular cell or string it can overcharge, and bad things can happen.
“There are some crappy cells to be sure, but the interconnects are done with welded nickle straps and after a few bounces, they can break and connect things that shouldn’t be. “
I don’t believe that’s a significant modus of e-bike or scooter fires. In the cases where it does happen it would tend merely to open the circuit. Too high of a charge current or not terminating the charge at the proper time are the principle causes. Neither of these conditions tend to occur often with OEM battery packs or chargers; but are almost expected when chargers are swapped or rush charging jobs are attempted or a pack is built from inferior cells (high resistance or other defect), such as at the NYC e-bike delivery outfits.