As has been previously stated, Thermal runaway occurs only min NiCad batteries. It can happen due to high charge current due to battery being fairly low in charge to start with, or having a very large load placed on it (too many starts tried in short succession). These high current will cause the battery to get hot, and in some cases can cause hotspots within individual cells. . .The hot spots cuase their own mini battery to form (for want of an easier explanation), and allow for local high current discharge, cusing more heat, cusing more hotspots and so on (Thus the term Thermal Runaway).. .. .Ther is no way in an aircraft to stop this once strarted, so the only thing to do ids turn off power and go away for a few hours. (not much that can be done out of the aircraft either for that matter). . .. .Do not try to remove the battery from the aircraft, as it can be extremely hot and will cause great bodily damage. It can also explode wich will cause even more bodily damage and spray hot metal , plastic and potassium hydroxide ( burny stuff even when cold) every where. . .. .If absolutely neccessary, move the aircraft away from other aircraft, people and buildings and let sit. Check it tomorrow, and replace with a serv battery. the over heated battery will in all probability need extensive cell replacement (and expensive) due to heat damage to adjacent cells. (assuming that the battery and plane are still in one piece.) <img border="0" title="" alt="[Eek!]" src="eek.gif" />