Tesla was having issues with fires a while back from over charging. I know that lithium batteries are susceptible to catching fire if over or under charging or unequal charging.
There was a huge issue with rc batteries burning houses down because of that reason as well, so they started selling charging bags in case a fire broke out the battery would be contained and not burn your house down.
On a show I watched called hasta Alaska their vw bus had a lithium cell made from computer batteries that caught fire because the solar panels weren't covered during storage and over charged the cell. Burnt their bus to shit.
The tech has improved since on lithium and it's more rare but still happens. Electrical things with that high of voltage are not to be taken lightly.