Suggestions / comments on mounting batteries aft of the firewall?

[idubrov]

What do you think about this mounting of two EarthX batteries firewall aft (the idea is shamelessly stolen from this post)?

I will attach these two boxes in three locations.

1. "Lip" (the right side of the first photo) gets attached to the firewall angle with 5x AN426AD4 rivets (flush inside the box).
2. "Outboard" side (the top of the first photo) gets riveted directly to the rib with 5x AN426AD4 rivets (flush inside inside the box). I don't think I need any doubler there on the rib.
3. I wasn't sure about the cantilevered corner of the box (the bottom left of the first image), so tentatively, I'm thinking one long angle along the box attached with a single AN3 bolt to a vertical angle on the central rib. See the second photo. I thought it will be difficult to put multiple rivets there, therefore a bolt attachment. The angle will be 3/4"x3/4"x0.062" (thinner than on the photo).

The whole "top" part will be covered with a thin sheet (0.032", probably). EarthX manual specifies 14ga, but I thought that in my installation it should be okay (since box will not be "hanging" on this sheet).

The long horizontal angle will have rivets loaded in tension, but with the weight of the battery, and the rating of AN426AD4 rivets, I thought it would be okay.



P.S. Alternatively, I can put a bracket like on the third photo.

 

[idubrov]

Okay, this was a disaster.

It kind of worked, but these boxes were not easy to rivet: countersinks I had to make with an angle drill, box flanges where I didn't want them and there is no support where I did want it. And then I had to replace the top cover (which I screwed up because I didn't realize box flanges would get in a way).

So I think I'll scratch all that and fabricate my own battery holder, from angle stock and/or my own design for sheet metal... Need to design it with better manufacturability in mind, too.

 

[B Cunningham]

Earth X batteries are so light…. Do you really need something that robust? I have one Earth X immediately behind the fire wall, and it makes it difficult to access of course…

 

[idubrov]

Earth X batteries are so light…. Do you really need something that robust?

I don't think I do. But I used existing boxes, and didn't want to leave one corner "hanging". Which is why I came up with this ridiculous contraption to attach it to the central rib.

The forward-facing part of the battery (the bottom) already rests on the firewall stiffener. So I only need to support the rear-facing part (the top with the terminals) somehow. And prevent lateral movements. And prevent it moving up, too. Which is like... building a box