Not trying to freak you out but check out this vid of a poor guys 233 catching fire, I've had this sort of thing happen more times than I care to elaborate on but luckily not in any of my high end boats. You can take all the precautions in the World but there is always a risk when dealing with these sorts of beasts. Hopefully in the near future these things will be in the past once cell technology presents an improved technology, actually for anyone reading this that has Netflix, a great documentary I just watched is called; "Search for the super battery"...some pretty cool stuff coming.
https://www.youtube.com/watch?v=mma47wzuT-w