A Gulfstream Galaxy Flight Crew declared an emergency and landed as soon as possible following receipt of a battery overheat warning. Subsequent investigation determined the source was actually a faulty sensor.
Synopsis
A Gulfstream Galaxy Flight Crew declared an emergency and landed as soon as possible following receipt of a battery overheat warning. Subsequent investigation determined the source was actually a faulty sensor.
Narrative
While climbing through about 26;000 FT on the way to 40;000 FT a 'Battery Hot' message appeared on our CAS system. The battery temperature indicated 170 degrees and in the red. The checklist had us isolate the battery from the bus so there would be no charging. We monitored the temperature for a few seconds to see if there was a change. There was none. At this point the checklist says if the temperature is above 160 degrees to 'Land as soon as Possible.' The fear of course is a NiCad battery thermal runaway. We had no choice but to Declare An Emergency as that action would enable us to land as soon as possible in case it was an actual thermal runaway of the battery. We landed approximately 15 minutes later being given priority handling by ATC and making an ILS approach. The battery temperature indicator read 170 degrees all the way to engine shutdown. After landing it was discovered that the battery was cool and the temperature sensor was faulty giving us the maximum reading. My gut feeling was there was not a thermal runaway; but I felt it not prudent on my part to second guess the system and elected to take the safest course of action.
Second reporter narrative
No substantive additional information was provided in the secondary narrative.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.