Battery behind firewall attachment

Clouddancer · #1 11-12-2014, 02:22 PM

I want to put my battery (for instance Odyssey PC680 planned) in the originally foreseen location by Vans, i.e. behind the firewall, between the rudder pedals. For those who have that location for the battery: how have you attached the battery? Have you reinforced the floor, if the battery sits on it? The plans are not very specific on this.

John F · #2 11-12-2014, 03:15 PM

I think that's a good place to put it and a good battery choice. That battery used to come in a steel box. What I did was, separate the battery from the box, mount the box to the side of the floor web and the floor.Then the battery would slide down into place. I made a little bracket to hold it down. It's hard to work in that space but it worked well for me.

nauga · #3 11-12-2014, 09:09 PM

Quote:

Originally Posted by Clouddancer

I want to put my battery (for instance Odyssey PC680 planned) in the originally foreseen location by Vans, i.e. behind the firewall, between the rudder pedals. For those who have that location for the battery: how have you attached the battery? Have you reinforced the floor, if the battery sits on it? The plans are not very specific on this.

I'm not where I can check right now but my plans did show a holddown made from AL 'U-channel' on top of the battery and clip nuts on a shallow AL angle box on the fuse floor. The battery fit in the box and loooong bolts through the U-channel clamped it down by the clip nuts. I'll get a drawing number and maybe a photo of that part of the drawings in a few days.

Other than the additional stiffening provided by the AL box riveted to the floor there was no additional reinforcing.

PCHunt · #4 11-13-2014, 01:13 AM

Not much difference in CG by mounting the battery just behind the firewall vs. just in front of the firewall. Much easier wiring and safer to mount on the firewall in the engine compartment. Much more difficult to service the battery behind the firewall.

That is, unless you are replacing a battery already installed behind the firewall.....

Is this a new installation? What is your reasoning for mounting behind the firewall? Curiosity strikes again!!

Clouddancer · #5 11-13-2014, 03:51 AM

Thanks for the replies!

Nauga, I would especially be interested in the box on the floor. I am just a bit concerned by just putting the battery weight on the floor without any other support.

PCHunt, it's a new installation. The previous builder has foreseen to put it there and has already made a forward attachment bracket to srew a bolt in and then stopped... But the main reason is, that the space forward of the firewall is pretty much stuffed by the Christen inverted oil system and it's hoses, heater valve, oil pressure & fuel pressure and flow sensor. Otherwise the decision on the location may have been different

fixnflyguy · #6 11-13-2014, 06:00 AM

I have my battery "per plans" in the tunnel between my feet. The plans install 4 angles riveted through the lower skin to hold the battery in place, and utilize a simple aluminum hold down. Its a good location, but a pain to get to. I also have a console installed from the instrument panel to the tunnel,in which my transponder and glovebox are in, along with the tunnel close-out, so the battery is really covered up. To get to my battery it takes removing the forward skin panel, pulling my transponder and removing the cover plate...not easy!. I did at least wire it with a battery tender plug that is inside my oil door in case I need to charge it. I am likely going to move mine on the fwd side of the firewall in the near future. If I didn't have the console, it wouldn't be as significant an issue, but its just not very easy to get to.

blackbeard10 · #7 11-13-2014, 09:03 AM

Put my battery (the smaller Odessey 545) on the front of the fire wall. I can't twist into Gumby shapes that easy to access the proposed Van's location so the Van's location was not a choice. During different tweaks of my 4, I have disconnected the battery probably 8 or 9 times. I think ease of disconnection is big consideration.
You don't have a lot of room to play with on the firewall in a 4 (an understatement) so that is a negative for the forward firewall location. You might ask if I have ever had a problem starting with the smaller Odessey. Not at all even in winter. The Odessey charger plug is located near the Oil door for easy access and works well.
I am also installing a Piper external power receptacle under the panel and carry a set of Piper jumpers on long trips. There is an after market moounting bracket for the smaller Odessey that is well made and reasonably priced.

N999BT · #8 11-13-2014, 09:59 AM

I built my -4 with the original battery in the original location. As others have said, its a pain to get to.

So, along with some other moves to lighten the plane, I moved the odyssey into the right cheek. I made a battery box out of aluminum, and attache it to the engine mounts with adel clamps. Now I use the old battery location for forward baggage. It really helps with the CG on cross country flights with baggage and a passenger, so if you can swing it, I would put it up front.

Clouddancer · #9 11-14-2014, 09:13 AM

Battery in cowl cheek is an innovative solution, if the firewall is already too crowded. N999BT, would you have a picture of your installation?

I see that the original location in the tunnel is difficult to access.

If I have to go with that solution, I will have to pay attention to facilitate access as much as possible, altough I have a console down from the panel to the tunnel. A battery tender plug is planned.

kjlpdx · #10 11-14-2014, 10:38 AM

in my -6A I have had the battery in it's original position, between the pedals, and then later moved it to the engine compartment. it is now back inside and will remain there. the original plans, circa 1997, had you build an AL box fastened down with piano hinge. I modified it to allow me to also hinge open the top corner of this box to give me easy access to the positive battery terminal. jumping a battery inside the cowl is hard and messy and dangerous. I added a chunk of foam as a spacer when I went to the half battery. the negative terminal has a brass "L" that bolts to a firewall ground stud and holds the battery secure inside the box. the space gained by moving the battery to the engine compartment is totally unused otherwise. similarly the center space between the battery and the spar is best used to hold maps, lunch, etc... because your feet never go there anyway.
on the same line I have had the throttle/mixture/carb heat cables on a vertical channel as originally designed by Van, and then changed it to an under panel mount that everyone seemed to be going to. after installing a center arm rest I moved all the cables back to the original design which allow the throttle to be the exact elevation to my hand resting on the arm rest [I fly with my left hand on the stick]. all my cables are run thru this channel. despite designing it to be easily removed for maintenance, I've discovered that it doesn't get in the way as one would have guessed. so, Van wins again!