AGM batteries do vent, albeit only small fraction what a traditional battery will do.

Although if charged very carefully they will not vent, Optima says:
Quote:

crab45 love your ute, easy to touch up and looks mean enough to scare little kids :)
Utes have so much room under the tray thats awesome but a small AGM battery can fit almost anywhere also and never leak fumes or corrosive acid onto you metal.

Is it really worth putting under the tray?
I just put mine infront of my LHS wheel tub aha.

yes it has been done different ways. Lots of room under the tray.

See the 'truck' section of Battery Relocation

I know this is on the fuel tank side but wouldnt be hard to move it across. Mine was very simple to make, just used 25x25 angle cut to the size of my battery (plus a little extra) and some flat steel as side braces. I also made plates that go inside the vehicle to help brace the wall as its only thin steel

http://datsun1200.com/uploads/newbb/5996_5135c4e21fd63.jpg

Have a look at my build, there are a few more pics of the battery tray.

ive seen a bloke just cut a hole out of his tray floor, i think it was opposite side of the fuel tank and weld up a box to fit it.

there was also another one that x member Smurf did, DDgonzel might be able to show you that one...

I think Gylezy (doesnt get on here much anymore i dont believe) had a well designed one in his ute build thread, check it out..

Hey guys as title suggests I'm wanting to make a box for my battery and mount it under the tray. Just wondering if anyone else has done this or has seen if done. Wondering how hard it would be?