I got an optima 34R battery yesterday to replace my failing stock battery. I figured out a way to secure the battery to the tray without having to make the popular adapter plate.
The Boxster's battery tray has 9 holes in it. 5 are down the center of the tray in the long direction, 3 of them are threaded for the locking bracket and two are through holes at the ends of the plate. The 4 others are for mounting the tray to the chassis.
The Optima battery has flanges at the lower short ends for mounting, just like the Porsche part does. The problem is that the Optima battery is too short to match any of the threaded holes in the tray correctly and placing it all the way over to the driver's side like the stock battery makes the positive terminal too far away for the cables to reach. The Optima needs to sit about centered on the battery tray for both cable to reach the terminals.
The Optima comes with some mounting brackets, one of which functions exactly the same way as the stock steel tie-down bracket, it grabs the flanges at the edges of the battery. So now I have two tie down brackets that will grab the flanges of the battery.
Test fitting showed that if I used the Optima tie down in the extra hole on the driver's side, I just needed to extend the tie down on the passenger side to grab the passenger side flange of the battery due to the hole locations. I made a 4" by 2" plate of 1/8" aluminum, turned the hold down around so it would grab the aluminum plate properly, and screwed everything down. The driver's side bracket is held in place with a stainless button head screw, washer and nut.
Everything is very tightly held down, the battery posts are at the same height as stock and it all cost about $1.50 in extra stainless steel hardware.
http://i2.photobucket.com/albums/y37/bellylint/optima_install/HPIM0609.jpg
http://i2.photobucket.com/albums/y37/bellylint/optima_install/HPIM0605.jpg
http://i2.photobucket.com/albums/y37/bellylint/optima_install/HPIM0606.jpg
http://i2.photobucket.com/albums/y37/bellylint/optima_install/HPIM0607.jpg
http://i2.photobucket.com/albums/y37/bellylint/optima_install/HPIM0608.jpg
Threaded Mode
