Here's another Mitsubishi example of how simply dropping a Lion battery (during testing for example) can set the scene for thermal runaway. Something to be kept in the back of the mind, anyway.
Mitsubishi Motors recalls plug-in hybrids -NHK WORLD English-
Quote: "The maker has already suspended production of the 3 models.
Mitsubishi says the recall was triggered by 3 cases of batteries short-circuiting and melting. The company says its investigation found that some lithium-ion batteries had been accidentally dropped on the floor during testing.
The ministry says the batteries with damaged electrodes could short-circuit during charging, or even overheat and melt."