Need a good idea or two on how to mount a battery to a fiberglass body

My Maxton - although it appears to be "factory built" - has an ingenious method of fitting the battery - hook it up to the cables and throw it into the trunk. As far as I can tell, it's short at least one bracket (kinda like its owner) that actually hold the battery to something. The trunk has a space that is clearly intended for the battery, heck, there is even a bracket for a trickle charger, but the battery is mostly held in place by positive thoughts and the negative cable.

I'm planning to replace the battery with an Odyssey with a bracket as the existing battery is on the way out, probably from all the bouncing. My question now is - how to I attach the bracket to the car? The battery nook has a pretty sturdy fiberglass floor, so would it be sufficient to drill the appropriate holes and use some large fender washers to spread the load around the bolt holes?

Or would I be better off to make some sort of reinforcement plate out of 2-3mm thick aluminium to spread the load across a bigger surface?

I'm not sure how the Odysseys are built, but in the 911 world, it's pretty common to drill and mount an Optima to a plastic cutting board and to mount that to the floor, in place of the ginormous original battery. No bracket over the top.

I don't have any photos, but I've done it and it worked really well in that application. 

In reply to BoxheadTim :

Buy a boat battery box. It comes with a strap and brackets to tie it down.  
Your battery takes all sorts of abuse bouncing around even properly strapped down. 

Boat box is probably far too large to fit the space available. I like the plastic cutting board idea, although I have not seen it. Maxton glass is sturdy enough to use bolts and fender washers as well.

I love the cutting board idea, although I'd overengineer it by using one under the fiberglass as the load spreader, if possible.

Then again the fiberglass WAS sturdy enough to handle a battery bouncing around.

This is not my photo, but here's the basic idea:

For mine, I cut and drilled the cutting board to fit where I wanted it, then flipped it over and drilled holes for countersunk machine screws to come up from the bottom (so they mount flush and don't stick out from below) to hold the battery to the board. I used the factory hold down points to secure it to the trunk floor.

I think I bought the cutting boards from Bed, Bath and Beyond.

I assume you're planning on the accessory hold down kit sold by Odyssey?  Assuming the spot where the battery goes is flat, I think I'd cut a matching size rectangle of aluminum of a similar gauge to go underneath the fiberglass.

The idea of mounting the battery to a cutting board and then bolting that cutting board to the body is a good one because then the body doesn't have to take the constant tension of the battery hold-down bracket, just the weight and inertia of the battery.

Found my photos. There's a metal lip on the floor at the top of the first picture that the board tucks under to secure that end.
 

Woody (Forum Supportum) said:

I'm not sure how the Odysseys are built, but in the 911 world, it's pretty common to drill and mount an Optima to a plastic cutting board and to mount that to the floor, in place of the ginormous original battery. No bracket over the top.

That is genius. GENIUS.

In reply to iansane :

Maybe, but I can't take credit for the idea.

In reply to iansane :

The original Porsche battery was massive, but mounted in a similar fashion, although it used a small clamp to hold the near end of the case down to the floor.

Totally stealing that idea for my Europa build

Cutting boards are cheap at the dollar store too. We used to buy them and cut them into strips to make chassis versus ground rubbing blocks. A whole season worth for a buck. Same UHMWPE material as the B,B&B ones.

Thanks for the suggestions - yes, I'm planning to use the Odyssey hold down kit for the battery, so the question is more "how do I bolt down the hold down kit".

While there is enough space for a battery, there really isn't a lot of space around the trunk, so anything I do to mount the battery has to fit into the same space as a size 34 (I think) battery. There isn't space to fit a battery box or similar, the battery is basically fitted in something that's fairly cubby-holish behind the rear wheel. 

In reply to BoxheadTim :

My apologies for taking this off on a tangent.

In reply to Woody (Forum Supportum) :

It's the tangents that make this forum interesting .

I like these fabricated battery hold-downs . They can be adapted to most situations with bolts or welding. Not terribly expensive either.

https://www.summitracing.com/parts/aaf-all76100?seid=srese1&gclid=CjwKCAiA866PBhAYEiwANkIneAymAn_QKloOm0SPq_4fPfqyziKGSA-1HwiFOzKcehgqyaTvuVvcTBoCwVkQAvD_BwE

This is the hold down kit I'm looking at: https://www.odysseybattery.com/products/hk-pc925-battery-hold-down-kit/