From what I'm reading on LifePo packs, you probably couldn't get them to catch fire if you tried. It seems the highest possibility will be to puncture them. I can not find a single incident of a Life pack catching fire inside a model, So I am leaning toward carefully charging them inside on my aircraft, unless I can devise the setup I want & figure a way to remove the 3packs. Joe- that's some very good info, & Dave, this is for my UF.. If I place my 2-2100mah bats in the standard location with my P-100rx, I will have to add lead, & I HATE, HATE, HATE LEAD!!! so I'll probably shift the batts into the nose & figue a way to extend the balance leads, then charge carefully & watch them like a hawk. thought about making the nose removable with a batt tray, then I could remove & charge all 3 batts, but dont really want to add the weight of that either