Miata Battery Mounting

My OEM battery kicked the bucket and I decided to shed some weight and go for the Deka ETX9. Now, let's avoid the "that will/won't work", as I've already discussed that, I'm on the skeptic side, but I'm going to give it a test run, if it doesn't work I'll go back to OEM-style, or a larger AGM.

I'm trying to figure out how to mount this think in the trunk. If the Miata used the two traditional threaded rods, that would be fine. Other considerations is that I raelly don't want to start whacking holes in the trunk pan or hacking things up, because this may not be a permanent installation. Also, the bolts that mount the little metal tabs to the the trunk floor no longer have anything that resembles a head due to a leaky battery, so removing those tabs and using the bolt holes may not be a viable option. Other than that, fire at will!

It's in the trunk for weight distribution. Why not save the weight of the battery cables and put it under the hood? You'll have plenty of random holes to bolt to.

In reply to chaparral:

That's an option, although with stock airbox, cruise control, A/C, P/S and an FM strut brace, it's a little busy under the hood

Drill out the bolts and replace them. Set the battery into the front center corner of the original battery hole. Press aluminum foil into the empty space around the new battery. Cut a filler piece out of a scrap of 5x9 decking or 2x6. Use original J-hook through a piece of inverted 1x1 aluminum angle to hold it down. Get crazy if you want with another 2" section of aluminum angle, inverted and bolted perpendicular to the top piece to keep the tiny battery from moving back.

Yes, I've spent entirely too much time thinking about mounting batteries into the trunks of Miatas.

My current theory was to screw some wood to the plastic tray to take up the empty space and mount it roughly front and center, like you said, but then grab some steel rod and heat that and bend it into sort of the stock hood but with a much bigger drop in it to press the new battery down.

Once I removed the stock tray thingy bolted to the trunk floor, there were enough holes to just run two threaded rods and a piece of angle aluminum across the top of the battery. Double sided tape on the bottom of the battery for a little extra help. Washers and nuts on the underside of the trunk floor. It's been solid for years.

When I used an itty bitty jet ski battery in mine a couple years ago, a couple blocks of rigid foam insulation to keep it off the fender and a few zip ties over it and on the inboard side of it kept it from moving at all. A season of autocrossing on Hoosiers and two track days resulted in ZERO problems or movement.

I'd still be running it that way now if I hadn't killed the battery through my own stupidity. I plugged in my OBD-2 scanner to check something during an event and left it plugged in for a week. Battery totally dead and they don't take a charge back after that. Otherwise it worked great and weighed something like 2 pounds.

Many organizations will (rightfully) not accept a battery held in place only with zip ties. In an actual crash that becomes a sparky projectile.

In reply to RedGT:

Yeah, I've seen zipties used as engine and transmission mounts, steering wheel attachment nuts, and fuel pump mounts, but I personally draw the line at battery tie-downs