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  #1  
Old 10-01-2021, 03:20 PM
bryanflood's Avatar
bryanflood bryanflood is offline
 
Join Date: Aug 2006
Posts: 127
Default Firewall mount battery box

Hello all,

thought some of you might find this helpful. I mounted a second battery on my firewall of the RV-10. When I test flew the set-up a stick on thermo-couple measured that the battery was getting too hot, so I tried a number of different combinations to cool it. In the stock configuration the battery would get to about 30F above the ambient in cowl air temperature. This heating was observed even with the alternator and battery isolated from the system, so the heating of the battery observed was due to radiant heat at least in part.

After some trial and error the best solution I found was this cooling shroud made from aluminum over the stock metal battery sleeve that came with the battery. (Odyssey battery metal sleeve like what comes in the stock vans battery mount kit) A 1" blast tube attaches to the box to provide cooling air from the back of the baffles. There is about 3/8 inch gap between the metal battery sleeve and aluminum cooling shroud. The cooling shroud is attached with bolts and standoffs through the metal sleeve that holds the battery. Half of the inlet to the 1" tube has been blocked off at the baffles with no noticeable affect.

With the new cooling shroud and a thermo-couple glued to the outside of the battery plastic shell in about the center of the largest face, the greatest battery temperature I have seen is about 90 F. The ambient cowl temperature, measured between the heater valves and the battery box (to the right of the battery), typically runs about 150F in cruise and up to about 200 on the ground after landing and taxing back to the runway for another take off on a hot summer day.

https://photos.app.goo.gl/4HuJRJTeYFp5SJBk6

https://photos.app.goo.gl/W88NSfZH6eSyrvpp8

Bryan

Last edited by bryanflood : 10-01-2021 at 03:23 PM.
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  #2  
Old 10-01-2021, 05:28 PM
lonkelm lonkelm is offline
 
Join Date: Jul 2008
Location: Landenberg, PA
Posts: 47
Default cool

Thanks for sharing, looks like a nice install.

I'm still on EMP kit so have no deep knowledge in this space, but why do we want a battery up there? Aren't most already nose heavy?
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  #3  
Old 10-01-2021, 06:47 PM
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bryanflood bryanflood is offline
 
Join Date: Aug 2006
Posts: 127
Default Battery on firewall

Lonkelm,

I wanted a second battery for a second alternator and the firewall seems like the best place to put it to me. I have another battery in the stock location.

In some ways the RV-10 is nose heavy in another it's not. I depends how you use it. If you fly solo all the time with one passenger only and limited baggage, then it feels nose heavy on landing and I fly with Ballast in the baggage compartment for better feel even though I am in C.G. range.

If you want to load the plane up for more utility with 4 people and a full baggage compartment (family plane) it seems to makes more sense to shift some weight forward, this gives more flexibility and in some scenarios more capacity, but then you need more ballast to fly solo and be in C.G. range and or get the good landing feel. It's sort of a trade off thing. I guess different builds will come out with different C.G. ranges but I have talked to other 10 pilots who experience the same.

Best regards,

Bryan
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  #4  
Old 10-01-2021, 07:07 PM
rvdave rvdave is offline
 
Join Date: Jun 2005
Posts: 456
Default

I put a earthx backup battery on the firewall and initially was getting a high temp indication so put a y in the baffle scat over #5 cylinder to flow air onto the battery and that took care of any radiant heat overheating the battery.
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  #5  
Old 10-02-2021, 09:56 AM
lonkelm lonkelm is offline
 
Join Date: Jul 2008
Location: Landenberg, PA
Posts: 47
Default

Thanks for those insights!!

Quote:
Originally Posted by bryanflood View Post
Lonkelm,

I wanted a second battery for a second alternator and the firewall seems like the best place to put it to me. I have another battery in the stock location.

In some ways the RV-10 is nose heavy in another it's not. I depends how you use it. If you fly solo all the time with one passenger only and limited baggage, then it feels nose heavy on landing and I fly with Ballast in the baggage compartment for better feel even though I am in C.G. range.

If you want to load the plane up for more utility with 4 people and a full baggage compartment (family plane) it seems to makes more sense to shift some weight forward, this gives more flexibility and in some scenarios more capacity, but then you need more ballast to fly solo and be in C.G. range and or get the good landing feel. It's sort of a trade off thing. I guess different builds will come out with different C.G. ranges but I have talked to other 10 pilots who experience the same.

Best regards,

Bryan
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  #6  
Old 10-02-2021, 03:13 PM
rongawer rongawer is offline
 
Join Date: Dec 2007
Location: Brentwood, CA
Posts: 763
Default Dual Batteries

Quote:
Originally Posted by lonkelm View Post
Thanks for sharing, looks like a nice install.

I'm still on EMP kit so have no deep knowledge in this space, but why do we want a battery up there? Aren't most already nose heavy?
If you're starting in with the idea of using dual batteries, I mounted two EarthX ETX900 batteries aft by modifying the mount for two batteries laterally mounted. It prevents any concerns over thermal issues, and the two lithium batteries are less than 10 pounds combined. It's a solid option, but does require running a second power wire forward; I have a 2ga for the main and 8ga for the aux battery running forward, along with a cross-connect contactor as well. The second wire is only 0.78 pounds added weight, so well worth it to me for the redundancy on my all electric installation.
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  #7  
Old 10-02-2021, 05:22 PM
lonkelm lonkelm is offline
 
Join Date: Jul 2008
Location: Landenberg, PA
Posts: 47
Default

This is what is penciled in my head, two in the back, but was considering the long wire run. I might think about primary up front and a backup in the rear to avoid two long runs. A shorter run will help with cranking power for primary use too.
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  #8  
Old 10-02-2021, 06:31 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,778
Default

Have you monitored battery temperature for the first 20 minutes or so after shutdown? I think that area gets hotter once all cooling air is removed, but have not made any measurements.
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  #9  
Old 10-03-2021, 07:58 AM
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bryanflood bryanflood is offline
 
Join Date: Aug 2006
Posts: 127
Default Battery temp

Bob,

after shutdown the in cowl air temperature rapidly rises and them starts to decay after a short period, like you suggest. The battery temp does not rise more than 10 degrees after shutdown, I am assuming this is due to the relatively cold thermal mass of the battery as compared to the air temp. Even in flight before the air blast tube install it would take some time for the battery to reach a steady state temp, something like 45 minutes to an hour.

Thanks,

Bryan
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  #10  
Old 10-03-2021, 08:17 AM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,555
Default 2 in the back

Like Ron pointed out, a better option would have been 2 batteries in the stock location behind the baggage compartment. Besides the benefit of having a few extra pounds as far aft is the obvious benefit of having the batteries in a cool location.
You are right about long wire runs but such decisions are always a compromise.
I have 2 installed at the stock aft location running 2 "fat" wire up each side of the fuselage to the front for starting and distribution.
I do monitor the temperature behind the fire wall, a sort of fire detector probe,
and I see temps from about 140F to 160F. my probe is located exactly where your battery is located.
Time will tell.
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