On Tuesday, January 10, 2017 at 10:50:49 AM UTC-6, wrote:
Thanks for the additional detail, CJ. The fact that the motor was run previously in the flight changes the picture significantly. However, it's still not clear why the pilot had to shut down the motor. In your original post, you said the battery was overheating, but the incident report says "battery power was low", which suggests the battery voltage had reached it's minimum. Which was it, over-temperature, or under-voltage? These are two very different things. If it was low voltage, then most likely the battery power was simply exhausted. If it was overheating, that suggests a failure of some sort. An OAT of 86F is not extreme, so it would be surprising to me if the battery overheated. Does the FES have any known limitations on motor run-time? My assumption was that it could safely be run continuously until the battery was empty.

I am also a fan of FES and am considering purchasing a sailplane equipped with it. I hope it's not true that the battery could overheat under such seemingly normal operating conditions.

My experience self launching the Silent 2 Electro is that Battery temperature has never been an issue. I have once or twice gotten a yellow warning for the motor temp when launching in Uvalde and Kansas on 100ish degF days. Slightly "throttling back" cured that with no issue. Finding a thermal helps a lot too.

The power consumption when cruising level is very low and motor temps have never been a problem at all when i've had to cruise on hot days. One of those days was a fairly long cruise in Lithuania where I ran the motor for about 35 minutes: http://www.onlinecontest.org/olc-2.0...htId=495576510