NiMH isn't as safe as you think it is. Improper charging and improper care for any battery can lead to serious problems. Just because it doesn't have the Lithium technology doesn't mean you're in the clear.
You must handle ALL batteries and ALL electronics with extreme care. Things can go wrong in a blink of an eye and sometimes are not reversable.
Oh, and this can happen to anyone. Just last week one of my buddies from my local flying club had his garage burn down, and he's one of the leading electric guys at my club (has been in it since the start). His charger received a spike from his power supply causing a ripple effect which eventually lead to the destruction of his battery. He took all precuations possible by using smart chargers, balancers, the correct LiPos, but even then things can go wrong. Most of the time the cause of the problem isn't even your fualt, so be careful, please!
