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Old 05-31-2017, 11:54 AM
sritchie sritchie is offline
Join Date: Jun 2015
Location: Boulder, CO
Posts: 130

Originally Posted by Guy Prevost View Post
I have a lightweight whirlwind prop and dual EarthX batteries on the firewall. I'm happy with my configuration.

I don't have to, but I typically carry 2ea 25lb sand bags in back when lightly loaded. The plane just flies a little better when it's not close to the forward limit. The real advantage is I can load up the plane without the sandbags and have no CG issues.

I was able to go from one PC680 on the firewall and a single alternator to two EarthX batteries, two alternators, and 3 contactors for a net weight gain of 1lb. The 1lb was basically from the additional large cables. Note that the original battery was already small and light for a 10.

Guy, do you have a picture of your setup? I'd love to see where you placed the batteries.
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Old 05-31-2017, 12:29 PM
Guy Prevost's Avatar
Guy Prevost Guy Prevost is offline
Join Date: Jan 2005
Location: albuquerque, nm
Posts: 1,155

I don't have any great photos, but here are a couple of marginal ones.

In the photo below, you can see the tops of both batteries. One lesson learned that hard way is that the bottom battery needs a radiant heat barrier to keep the case from melting. My battery functioned normally after significant heat damage to the case, but I've replaced it. Also understand that the placements might not be optimal. I rebuilt all of the systems in the plane and therefor had some additional constraints I wouldn't have had if I were starting from scratch. It originally had a single PC680 on the firewall.

My engine is removed at the moment for an unplanned overhaul due to cam and lifter corrosion caused by the previous owner not flying enough. The lower battery is removed due to the heat damage I mentioned above. It goes immediately inboard of the blue starter contactor.

Hope this helps.

Guy Prevost
Albuquerque, NM
RV-8a Built, Enjoyed, Sold
Two Kids: Built, Enjoying
RV-10, Bought, Rebuilt, Enjoying
Build / First Flight Video:
Build Log:

Arguing on the internet is like having a competition to see who can hit a brick wall the hardest. You may win, but you're still an idiot.

Last edited by Guy Prevost : 05-31-2017 at 12:47 PM.
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Old 05-31-2017, 01:02 PM
sritchie sritchie is offline
Join Date: Jun 2015
Location: Boulder, CO
Posts: 130

Wow, looks really hot in there. I may end up going one battery forward, one back to provide some redundancy in case the heat's an issue, and to keep the second battery out of that hot spot.

Thanks again!
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Old 05-31-2017, 03:32 PM
N427EF N427EF is offline
Join Date: Oct 2005
Posts: 1,510
Default Dual Battery

Another point of reference:
I mounted 2 batteries behind the baggage compartment where plans indicate.
Instead of one, I mounted 2x 15# Lead acid batteries similar to these.

The rest of my RV-10 is pretty much stock and I've never felt I needed more trim or more weight either in the front or back. Flies very well with 1, 2 or 3 passengers.
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 400 plus hours
Over 2500 Gallons of E10 mogas burned
Don't believe everything you know.
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Old 03-15-2019, 12:18 PM
EarthX Lithium EarthX Lithium is offline
Join Date: Feb 2014
Location: Windsor, CO
Posts: 220
Default Thermal battery box

Hi, we had a customer who was working on mitigating heat suggest we post our thermal battery box that was designed to assist in this endeavor on this thread. So here you go:
Fly Lightly,

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Old 03-19-2019, 11:54 AM
DJP DJP is offline
Join Date: Apr 2012
Location: Santa Rosa, CA
Posts: 85

I am shocked to see that some are suggesting mounting the battery, ANY battery on the firewall of a RV-10. I just went down that same road and ended up losing a perfectly good ETX900 that I had placed under the copilots seat years ago. When I had a new panel all Garmin panel built by Aerotronics and installed by Synergy in Eugene, OR, Synergy suggested moving the battery from under the seat to the firewall. That way it could not only serve as the backup up power supply for the instruments but I could also use it as an alternate way to start the aircraft. They had done that on MANY of the two seat versions of the Van's aircraft. We did move it to the firewall and I flew the aircraft back to California in late July. In August I flew to Colorado and to Arizona and it was very hot. Finally in about October when I attempted to use the backup battery on the firewall, it was DEAD! When I tried to remove it from the battery box it was difficult. Turns out the reason it was difficult was because the case was distorted. I ended up sending the battery back to the Lab at EarthX to find out what had happened. First of all, they said the temps in the compartment exceeded 140 degrees because that is the temp were the case starts to change shape. Secondly, the internal temp of the battery should never get above 125 degrees, obviously this happened. I wrote to Vans and to EarthX asking about the temps in the RV-10 engine compartment but no one knew what they were. Vans simply said "we know its too hot, put the battery in the back (also helps with CG). I decided to do some testing myself and found that the temps were all OK as long as the big fan on the front of the airplane is turning BUT when you shut it off, bad things start to happen. After shut down, if you open the oil filler door on the top of the engine compartment, the temps go to a max of 153 degrees before starting to cool down. That is obviously way past the 125 max that EarthX has said is the internal cell temp and also exceeds the 140 where the battery case changes shape. Well it gets WORSE, much worse. If you do NOT open the oil filler door, the peak temp goes to 165 degrees, four minutes after shut down. I recorded all of these temps and sent them to both Vans and EarthX. The VP at Vans called me and thanked me for the information as they really didn't know. I would post this test document data but it is in word format and I am not sure how to do that. If someone can tell me how to post it here I will. DO NOT PUT A EARTHX BATTERY IN THE ENGINE COMPARTMENT, YOU WILL BE OUT $499 JUST LIKE I WAS......
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Old 03-19-2019, 12:07 PM
echozulu echozulu is offline
Join Date: Mar 2018
Location: Ocean City, MD
Posts: 67

DJP, it looks like the battery box posted by EarthX one post up solves your issue. At 185 deg convection heat (i.e. after shut down) it takes 90 minutes of continuous heat at this temperature to raise the internal temperature to 140 deg.
RV-10 - Empennage 90%
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Ocean City, MD
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Old 03-19-2019, 01:27 PM
EarthX Lithium EarthX Lithium is offline
Join Date: Feb 2014
Location: Windsor, CO
Posts: 220
Default Clarification of data points

There might have been some typo’s on the degree temperatures listed that DJP posted so I wanted to clarify some data points.

The findings on DJP battery was the temperature was above 200 deg F, because it is at this temperature the ABS plastic case will begin to deform (not the 140 deg F listed).

The max operating temperature for the cells is 140 deg F or less (not the 125 deg listed). The max storage temperature for the cells is 158 deg F. When the temperature is above this, you will start to prematurely age the cells and cause damage. (Note: the PC680 lists 113 def F as the max operating temperature). These parameters are listed in the manual on the battery specification page.

What can be learned here is every battery, no matter what brand or chemistry, list the max operating and storage temperatures and if you exceed them, you will have premature battery issues. If you are moving the location of the battery from where the aircraft manufacturer designed it to be, there might be a reason why it wasn’t located there in the first place and testing the temperature, is an excellent idea. It is a very simple test, which DJP looks like he will list how he did it, to perform and would be a good idea if you do have your battery installed fire wall forward, again no matter what the chemistry.
Fly Lightly,


Last edited by EarthX Lithium : 03-19-2019 at 06:19 PM.
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Old 03-19-2019, 07:21 PM
DJP DJP is offline
Join Date: Apr 2012
Location: Santa Rosa, CA
Posts: 85
Default Sorry my mistake about the numbers

Kathy is correct, it is 200 degree's for the battery frame and 140 for the cells. Having said that, the tests that I ran shows that those numbers ARE reached easily on any given day and at some point I exceeded 200 because the battery was distorted. The insulated battery box that EarthX sells is supposed to mitigate battery damage BUT after paying twice for a $499 battery I decided to move mine to the tail where the regular battery resides. You remove the battery from a huge heat source and get CG help in the process. My test results are posted 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
Peak Temp 165 F Four minutes after shutdown
Within 4 minutes of peak, temps started dropping.
11 minutes after peak, temp dropped to 155 F
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Old 03-20-2019, 07:57 AM
majuro15's Avatar
majuro15 majuro15 is offline
Join Date: Feb 2013
Location: Charlotte, NC
Posts: 578

Kathy, I just received the insulated battery box and plan to mount it firewall forward on my 10. What about creating a lid for the top of the box that would still allow a blast tube to be on it (with an exit, of course)? I can see how the insulation can help prevent heat soak but with the top of the box still open, the lingering heat of the compartment can still get to the exposed surface of the battery. I think if the top was enclosed you'd have better protection from the residual heat after shut down.
Tim Huneycutt, Capt, NCANG
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