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  #1  
Old 10-27-2018, 10:00 AM
DJP DJP is offline
 
Join Date: Apr 2012
Location: Santa Rosa, CA
Posts: 60
Default 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.
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  #2  
Old 10-27-2018, 12:05 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,519
Default Nice: DATA!!

First, where was your thermocouple located and was it exposed to the same radiation as the failed battery?

My testing shows that running lean with high EGT's affects the under cowl temps. Yours may be less affected with higher airflow. What were your EGT during the cruise run? It probably is not going to make a difference for the heat soak as the energy from throttle off and rich during landing phase will have dissipated, but cruise may be different.
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RV-7
1st Flight 1-27-18
Phase II 8-3-18
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  #3  
Old 10-27-2018, 01:14 PM
Finley Atherton Finley Atherton is offline
 
Join Date: Nov 2005
Location: AUSTRALIA
Posts: 703
Default

I did a temperature test on my 9A firewall mounted EarthX battery. Can’t recall the exact results but on a hot day in cruise the environmental temperature at the battery location was near the max allowable operating temp for the EarthX (140 F) but I think was below the max allowable short term temp (185 F) on shutdown. To test I simply temporarily moved #3 CHT probe and attached it to the outside of the battery box. As a result I built a custom lightweight, sealed battery box with cool air ducted in.

Fin
9A

Last edited by Finley Atherton : 10-27-2018 at 01:19 PM.
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  #4  
Old 10-27-2018, 01:18 PM
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snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 1,394
Default

I bought a digital meat thermometer with a 6" probe on Amazon for about $15. I inserted the probe through the lower firewall near the outlet of the oil cooler. It's a permanent installation.
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  #5  
Old 10-27-2018, 07:18 PM
DJP DJP is offline
 
Join Date: Apr 2012
Location: Santa Rosa, CA
Posts: 60
Default Heat in the RV-10 engine compartment

I ran the temperature probe (40" long cable) through a tiny opening in the firewall and taped it into the battery box so it got the exact same heat that the battery had experienced. To be honest, I did not look at the EGT's I was only interested in the internal temps of the engine compartment. In reality I was only airborne for about fifteen minutes on each flight and never got above 4,500 feet so I did not lean the mixture.

Having anything exposed to average temps of 115 or so hour after hour can not be a good thing. In addition to opening the oil door after every flight I am convinced that any item that can be operated in a cooler environment will last longer and perform better than one under heat stress. EarthX told me that people that fly out of cooler climates have their batteries last longer than people flying out of Texas, Arizona etc.
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Old 10-27-2018, 08:40 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,519
Default

Quote:
Originally Posted by DJP View Post
I ran the temperature probe (40" long cable) through a tiny opening in the firewall and taped it into the battery box so it got the exact same heat that the battery had experienced. To be honest, I did not look at the EGT's I was only interested in the internal temps of the engine compartment. In reality I was only airborne for about fifteen minutes on each flight and never got above 4,500 feet so I did not lean the mixture.

Having anything exposed to average temps of 115 or so hour after hour can not be a good thing. In addition to opening the oil door after every flight I am convinced that any item that can be operated in a cooler environment will last longer and perform better than one under heat stress. EarthX told me that people that fly out of cooler climates have their batteries last longer than people flying out of Texas, Arizona etc.
Excellent location, Thanks!
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RV-7
1st Flight 1-27-18
Phase II 8-3-18
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