I think I posted this before, but here (this was on my RV-10).
For the builders that have, or plan on mounting the Earth-X battery on the firewall, I wanted to show what I did to protect/isolate the battery from the heat under the cowl. Everything was OK with mine till warmer weather set in. I took off for a long cross country at 78 degrees ambient and after 30 minutes of flight, I started getting the battery fault light 2 seconds on/2 seconds off light, which means the battery is above 150, or 170 degrees F (depending on which literature you look at), which is not good for longevity. I want this battery to be happy, and at $449.00 a pop for the ETX-900 (ACS price), I want this thing to last as long as possible.
Anyway, I solved my problem by fabricating a three-sided shroud, enclosing the top to bathe the battery in ambient inlet air taken from the top of the plenum above the engine. Since I did this, I haven?t had one overheating alert. This works. The shroud is about .060 to .075 larger in dimension that the outside of the battery box mounted on the firewall. This makes a curtain of cooler air around the front and sides of the battery box, and keeps the electronics (the BMS) cool inside the top of the battery case. I used 1 inch scat tube and two 1 inch flanges from ACS for the air connections. Since it?s a fairly snug fit on the box, the amount of air I?m taking off the plenum hasn?t raised my CHT?s , that I can tell. Also, I added heat shields on the nearest exhaust pipe and shielded below the battery bottom to protect from the convection heated air that happens after shutdown. This can actually melt/soften the molded battery case (this happened to my battery initially). The following pictures should explain things nicely.
Another ACS part shielding the exhaust pipe.
Here is the insulated shield I put under the battery/box on the firewall. It attached to the Adel clamp hardware for the pipe brace-no new hardware required.
The shield in place.
The box in place.
The flange installed where I took air from the plenum.