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Heat in engine compartment

DJP

Well Known Member
I have had my RV-10 since 2011. I did not build it but I have made major upgrades over those years. Even though it was a all glass cockpit when I bought it, the different parts did not talk well with the other parts. This caused me to have to press 15 buttons to shoot an ILS approach. It did it and it did it well but all of the button pressing was not something that I was used to.
In March, I took the airplane to Synergy Air in Eugene, Or and they were going to install the new panel that Aerotronics in Billings MT, was building.

When I bought the aircraft it had a lead acid battery under the co-pilots seat that was supposed to power the avionics buss in the event of a failure of the main system. When I tested this out, it only lasted for about 15 minutes which was worthless. I then installed a EarthX 900 battery and when I tested it, it did last for well over an hour and a half.

When my new panel was delivered to Synergy Air in Eugene, the Tech said that I was missing out on much of the capability of the EarthX battery. He told me that if he mounted it on the firewall, he could wire it so that if my main concord battery went south, the backup Earthx battery would start the aircraft. I said swell and he mounted it on the firewall and did the wiring to make that happen.

Several weeks after getting the aircraft back, I decided to try and start the aircraft using the "backup" Earthx battery. I turned on the switch and there was nothing. I removed the battery from the aircraft and attempted to charge it but it was distorted, not even the same shape as it was in the beginning. Since it is suppose to have over voltage and under voltage protection, I wondered what had happened so I shipped the battery back to EarthX for there lab to determine what had happend.

Friday I got the report and they say that the battery got to in excess of 200 F which caused the case of the battery to distort. I called Van's on Friday and they think that the IO540 engine puts out so much radiant heat (after engine shut down) that the battery failed because of that and that it needs to be mounted elsewhere.

My regular battery (Concorde) is mounted in the back but I was wondering if anyone had similar problems with batteries on the firewall. Synergy says that they have mounted batteries on all of the two seat models without any problems but this has cost me a $500 battery plus other costs and I am not a happy camper.

I have purchased a remote wireless heat sensor unit that I will install in the near future and will record all of the tempratures during the normal run of a IO540 engine. I believe that the problem is when the engine is shut down and the residual heat build up under the cowling. I will record the tempratures that I get and send them to EarthX, Vans and post them on this forum.
 
Firewall mounted batteries tend to suffer - as you found out. That said, having a big Concord battery in the back and a Li battery on the firewall is a combination that would rank last on my list of dozens of two battery options.

Most RV-10s need a big battery on the back for W&B. As such, this presents option to mount two batteries aft and get what you want for reserve power. I used two PC-625 batteries in my RV-10. If interested, PM me for details.

Carl
 
Not sure whether you've seen this thread about a cooled battery FWF on a -10. That said, I'd still prefer to put it at the back with the other battery - there is no electrical reason why you shouldn't.
 
I had 2 PC 680 Odyssey batteries mounted in the rear with dual masters/contactors on my -10. I could use one, the other, or both to start, so I always had a fully charged spare battery for avionics should I lose power. It did once when my alternator gave up on me at 90 hours. I was glad to have the extra battery as it got me home where I was able to make repairs in my hanger and not stuck 100 miles away. I'll have a similiar architecture on my RV-9A except using 2 Li batteries mounted on the forward side of the firewall. Hope I don't have heat issues. I would not take the risk of mounting a Li battery anywhere inside the fuselage.
 
Thanks so much for sending the link, it was very informative. I bought a new EarthX battery and a special "heat shielded" battery box BUT having said that I think I am going to move it to the tail with the main battery. I have talked to Van's and they think it is too hot because of the two extra cylinders but they have never done any serious testing. I have purchased some test equipment that I am going to install tomorrow and then fly the airplane. I will take temp readings during all phases of engine operations, I am especially how hot it gets when the engine is shut down and the prop stops providing air flow. I will send that information to Van's, EarthX and post the numbers here on the forum.
Don
 
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