RV14 2nd Battery Location - opinions please!

[TASEsq]

I’m wanting to install a second battery on the firewall.

The best location I can find is above the left hand firewall pass through (above the battery and starter contactor location). Behind this location is the big rib where the canopy gas struts mount.

I looked at using the earth x battery box but this is not going to work here - the battery needs to slide out of that vertically, and it will hit the firewall flanges. The battery needs to tip forward to get out.

So I think the best bet is to mount a Van’s battery box, but since there is a bend in the firewall at the top, mount it using 4 or 6 x an3 bolts into nutplates on a doubler on the aft side. I can align a bit of angle against the firewall, and rivet this at an angle on to the battery box to deal with the angle change in the e firewall.

What is everyone’s opinion of this location? Is it too close to the top cowl?

I could potentially move it lower if I relocated and blanked off the existing pass through (which is doable).

Thanks in advance. Any pics of where others have put their second batteries would be very helpful.

This is an overall location pic - I’ve measured and there will be about an inch between the front of the battery box and the engine mount, at the closest (outboard) point.


This shows the distance from the lug to the cowl / hinges / flanges. The lug on this side will be negative. I could potentially also use one of the 90 degree lugs here and have the cable come off the front? (Not sure if this would interfere with the hold down bar).



This shows how low I can go without having to move the existing firewall pass through (which I can do if need be):


This shows the angle created due to the bend in the firewall top


I would use a bit of angle like this - riveted to the battery box and bolted into nutplates / doublers on the back side.


There is even the potential to put a relief cut in the angle, and bend it to allow a bolt to go through the cross-bar underneath the bend where the firewall sheets join. But I think this is probably overkill?

 

[GK14]

Here's what I ended up with on my 14A with exp119, single alternator. The extra layer over the firewall is Dan Horton's firewall insulation kit.

No issues with cowling installation but it's close to the oil pressure sensor line. Your EarthX battery may be a bit taller than what I have installed.

 

[mstrauss]

I am putting the second battery on the left side somewhat symmetrical to the Vans standard location on the right. I don't plan on using the master & starter relays in their stock location, as Im installing EFII. This gave the opportunity to use some of that space for a second battery. I toyed with the idea of using the smaller size earthX battery to allow more mounting options, but decided against it, due to concerns with needing a battery while on a trip. A standard size box, just gives options. I did lower the second battery a bit to not interfere with some of the other firewall mounted stuff like the sensor block on the top left. I also decided to use nutplates to mount the battery box instead of riveting it in place. I wanted to be able to move it out of the way in case some significant service in that area came up. One issue to deal with was a pre punched firewall penetration for wiring, and the holes to mount the relay doubler. When I created a bubbler for the battery box mounting, I incorporated a patch for the wiring hole. Sorry, I don't have a snap with the box in place, but I think you will get the general idea from the below pictures.

 

[Ralph Inkster]

Do you plan to hold down your cowl with camloc fasteners? Not much spacing there between a live wire & a metal camloc socket.
Also the bottom bracket is below the firewall bend, are you accomodating for the forward tilt of the firewall behind the battery?
Last, have you trial fit the engine mount on the firewall to see if there will be interference?

 

[Ralph Inkster]

Hinge the front of the battery box. Pull the hinge pins and the battery can tip out. No problem. You can also mount items such as the manifold pressure transducers if required. Upper locations (cooler) are preferred to lower locations on the firewall.

View attachment 106751View attachment 106752

This is mounted pilot side FWF low. I would not recommend this location but higher up on the firewall. (30 degs cooler higher up) Mount slightly lower than you have it and blank off the passthrough and relocate.

Can't remember the source but I was told it isn't a good idea to mount MAP sensors low, moisture in the lines could potentially drain downward into the sensor & ruin them.

 

[TASEsq]

View attachment 106787Do you plan to hold down your cowl with camloc fasteners? Not much spacing there between a live wire & a metal camloc socket.
Also the bottom bracket is below the firewall bend, are you accomodating for the forward tilt of the firewall behind the battery?
Last, have you trial fit the engine mount on the firewall to see if there will be interference?

Should have mentioned - standard cowl hinges.

The image descriptions above show how I planned to work around the firewall bend.

I haven’t fit the mount but done some measurements. It’s the same lateral location as the stock box on the opposite side.

 

[TASEsq]

Of course, can't remember the source. Somehow, I doubt moisture is an issue with temps operating in the 160 F (20 mins after engine shutdown) range plus a blast tube. To date over 700 hrs. and 6 years no issues with these sensors. (Checked every run-up preflight)

Here’s the source. I’m not sure how you would mount it “down”. Most installations I’ve seen are on the firewall with the ports ‘forward’

 

[TASEsq]

Look at the picture I posted. It's on the FWF with the ports "forward" Does this look down?

View attachment 106803

In general terms, I think the wiring should have a ‘drip loop’ - or at least head upward to the connectors.

 

[Ralph Inkster]

Of course, can't remember the source.

Yeh I can’t remember which mechanic told me many decades ago about these GM type MAP sensors having a record of failing in cars from moisture, their solution was to reposition them higher than the vacuum source.

 

[TASEsq]

Can anyone speak as to whether they think the terminal will be too close to the cowl?

This will be the negative on this battery.

 

[Carl Froehlich]

Here is how an RV-14A builder added a second PC-680 to his plane.
Carl

 

[TASEsq]

Here is how an RV-14A builder added a second PC-680 to his plane.
Carl

Thanks. Mine is a tailwheel.

 

[integlikewhoa]

I'm assuming your looking for a bigger backup battery then the 680c?

Here is a pic of a 680c mounted in the spot you were looking at.

https://vansairforce.net/attachments/screen-shot-2020-08-12-at-3-50-57-pm-png.1187/

Taken from this thread.

Backup/second battery location

So my 14A will have an efii system so I'm looking for a place to install a full sized back up battery. I want to use two Earth X batteries. The earth X battery box fits pretty well where the original battery box goes. I'm searching for the 2nd location and have come up with a couple of options...

vansairforce.net

I'm planning on a 900 in the stock location and a 680c in this location. Can use the EarthX BB-CO2 mount to pull out front or cheaper EarthX BB-CO in that pic if you want to slide up. Seems like either works.

 

[TASEsq]

I'm assuming your looking for a bigger backup battery then the 680c?

Here is a pic of a 680c mounted in the spot you were looking at.

https://vansairforce.net/attachments/screen-shot-2020-08-12-at-3-50-57-pm-png.1187/

Taken from this thread.

Backup/second battery location

So my 14A will have an efii system so I'm looking for a place to install a full sized back up battery. I want to use two Earth X batteries. The earth X battery box fits pretty well where the original battery box goes. I'm searching for the 2nd location and have come up with a couple of options...

vansairforce.net

I'm planning on a 900 in the stock location and a 680c in this location. Can use the EarthX BB-CO2 mount to pull out front or cheaper EarthX BB-CO in that pic if you want to slide up. Seems like either works.

I’m not wedded to this battery - this would be my essential side (not cranking) so it could even be a smaller capacity.

What was hoping for were 2 identical batteries - this battery won’t see cranking loads, so the idea would be every 2 years or so to put a new battery here and rotate this one to the cranking spot. Also, using this box means if the earthx fails somewhere I can replace it with an Odyssey more easily as a temporary measure. (Or use the odysseys if w&b is an issue).

 

[Carl Froehlich]

I’m not wedded to this battery - this would be my essential side (not cranking) so it could even be a smaller capacity.

What was hoping for were 2 identical batteries - this battery won’t see cranking loads, so the idea would be every 2 years or so to put a new battery here and rotate this one to the cranking spot. Also, using this box means if the earthx fails somewhere I can replace it with an Odyssey more easily as a temporary measure. (Or use the odysseys if w&b is an issue).

No reason not to operate two batteries in parallel for normal start and operations. Makes for easy starts. My backup modes have the batteries split out.

Carl

 

[TASEsq]

No reason not to operate two batteries in parallel for normal start and operations. Makes for easy starts. My backup modes have the batteries split out.

Carl

Agree. I have a x-tie in the system to allow this if I choose. Also using the gad27 keep alive for the main bits of gear.

 

[SonexGuy]

I’m wanting to install a second battery on the firewall.

The best location I can find is above the left hand firewall pass through (above the battery and starter contactor location). Behind this location is the big rib where the canopy gas struts mount.

I looked at using the earth x battery box but this is not going to work here - the battery needs to slide out of that vertically, and it will hit the firewall flanges. The battery needs to tip forward to get out.

The EarthX batteries are light, so need far less support than the old, heavy batteries. I made two battery boxes, and made them so the entire front face can be removed, or pivoted forward, all by using piano hinges. This would allow you to tip the battery forward to clear the firewall flanges, or other obstructions. Maybe even allow other locations.

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[TASEsq]

Anyone feel the battery terminals would be too close to the cowl?

If I moved it down, what’s the best way to cover the hole? I have some thin stainless - I could screw on a pair of mating plates with sealant using the existing holes but would somehow have to work out how to make the screws flush. Maybe a thin stainless sheet on the front, dimpled for the screws and a countersunk aluminium plate on the back.

 

[TASEsq]

I decided to go for that location. Ended up with about 1” between the top of the terminal bolt and the cowl. About 1/2” from the boot to the cowl.