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ETX900-VNT install forward baggage

N82VM

Well Known Member
I’ve read all the pros and cons of the battery in the forward baggage, and also the pros and cons of the Earthx in the cabin. I’m good to go on those topics.

What I do have questions on are

1) Install in a QB ie no access to the bottom of the baggage floor
2) Where did the vent tubes route for discharge overboard

Please share your install wether it was SB or QB if you have that setup
 
My opinion

I've used this chemistry in my 14 and many years before in various other airframes. I'm not sure of your set-up but look at airflow front to back of your airframe. If there is a decent flow rate front to back, then venting most likely not needed. The 10 I'm building has batteries in the back and will not need any type of vent system.
 
Airflow through the cabin

Previous post not written very well, if you or a passenger are between the battery and airflow through the cabin venting outside probably a good idea. These types of batteries are very stable as long as you take care of them. Draining the batteries below 2.75 volts per cell (11 volts) is problematic although most suppliers go to extremes to have a BMS that prevents this type of discharge.
 
1) Should it vent overboard directly through the forward baggage floor
2) Should it vent through tubing routed from the front to the back and vent somewhere out under the rear baggage?

Not sure if having an overboard vent up front near the exhaust would present CO issues
 
My ETX900V is mounted aft in my 8 and is vented through the belly skin behind the aft cargo bin. I used short lengths of 1/4” tubing as exit ports which are attached to a piece of angle. The angle is glued to the interior of the belly skin and serves as an anchor for the vent tubes which are cut at an angle flush with the bottom of the skin. I’ve not experienced any issues with engine exhaust entering through these homemade vent ports.

I’ve just started construction on another RV8 and intend to use the same battery and mount it forward in the same area you are. For now, my plan is to use one of Earthex’s vent ports and either mount it in the bottom skin just forward of the right main gear strut mounting bay (abeam the exhaust ramp), or perhaps mount it on the lower right side of the fuselage (which probably would be a bit unsightly.) I don’t think it’s necessary to put the vent port in the back and run vent tubing aft under the floor the length of the cabin for a forward mounted battery.

One consideration is if you intend to install a smoke system in your plane (as I have) is that even with check valves in your smoke oil lines, you most likely will still get some residual oil running down the belly of your plane. Any obstruction (e.g. an antenna) or exit port will gather oil (and dirt) there which, if not kept clean, could potentially block the port.

Regardless of what you do, I would follow Earthex’s recommendation to vent the battery directly to the outside of the plane. I would not rely on cabin airflow alone to vent any toxic fumes in case the battery had a thermal overload.

Regards,
J Baker
RV8
 
Good points, and I plan to vent it outside. I just sent a question to the tech dept of Earthx about vent tube lengths. This is not addressed in the manual with the exception of a 6” vertical length being required between the battery and the exit. I posed the question to them about a maximum run from the vent to the exit.

For a forward baggage install, unless there’s a run limit or another reason I have not thought of, then you could potentially run it out the wing to exit there. Would solve the smoke oil dilemma
 
I put an ETX 900 in the forward compartment. I first made up a bracket that attached to the lower longeron and then had two attachment points that make up a triangular relationship. My aeronautical engineer friend told me to do it that way. It's very light and rigid and it allows you to use the bracket made for the battery. Not shown in the photos, I drilled a 3/4 inch hole not the floor below and there are some holes in the RH undercarriage box where you can run some conduit out and I made an exhaust port that went through the cover plate. The tube from the batteries runs inside. The battery cranks my IO375 with high compression pistons like there's no plugs. My aircraft has the system 32 EFII and you can see the ECU's. I moved them to the upper forward baggage compartment. With an electrically dependant aircraft, I went the whole way and put an ETX 900 in the back to power the essentials. I ran the vent tube all the way back and it exits into the rear empennage fairing. You can see the oxygen sensor box on top of the battery. Originally I had an ETX 680 and the whole compartment was sealed with a NACA duct and an exhaust port but when I upgraded to the 900 it was no longer necessary to have the compartment sealed. I hope this helps. You see the final iteration there but it was a lot of unnecessary work and I wish I'd just gone straight for the 900.
 

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Earthx tech support says “there’s no limit on the length of tubing from the battery and they sell it by the foot…”

That answers the overboard port placement/location question.
 
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