Heat in engine compartment, Part II
On October 24th I posted a problem that I was having with heat in the engine compartment that destroyed my EarthX 900 Lithium battery. I check with Vans and EarthX but no one knew exactly how hot it gets in the engine compartment, Vans just repeated that they recommend putting it in the back. Wanting to know exactly how hot it did get, I purchased test equipment and documented the results. I did one flight and recorded all of the temperatures and then when I shut the engine down I opened the oil service door to let the heat escape. On the second flight I did the same thing except that I left the oil service door closed and recorded those temperatures. The results are below:
Test Equipment used +/- 1.8 Degrees accuracy
Lycoming IO-540 Engine Compartment Heat Test Results
Outside air temperature at engine start 59 degrees F.
Idle 91 F
Taxi 107 F
Run up 101 F
Take Off 112 F
Climb 119 F
Cruise 115 F OAT 69F @ 4,500 Feet, MP 21/RPM 2300
Descent 110 F
Taxi 108 F
Engine shut down with oil filler door wide open:
Max temp 153 F. Temps increased for 8-10 minutes after shutdown @ 15 minutes temps started dropping.
Same Test with Outside Air Temp 81F
Engine shut down with oil filler door CLOSED:
Shut down temp 125 F
In two minutes 155 F
Max Temp 165 F Four minutes after shutdown
Within 4 minutes of peak, temps started dropping.
11 minutes after peak, temp dropped to 155 F
Bottom line, Vans is correct, it is way too hot to have a thin walled battery like the EarthX on the firewall, I am moving it to the tunnel where the main battery is located.