yes I know they give off fumes but the odyssey battery is a dry cell right? The standard battery is filled with liquid (dangerous) of course to install without it being enclosed.Well if it's not a good idea then how about a link to how to diy and relocate it to the trunk,and also thank's for the safety information guy's.
Odyssey is a deep cycle battery. Dry cell is what you put in your tv remotes, kids toys, flashlights, etc. A, AA, AAA, C, D, etc.
Optima also makes a deep cycle battery.
Every battery is going to give off fumes. Some like Optima claim that under normal use they don't, but if they are overloaded, heavy loaded (big stereo system, extra accessories, etc.), or over charged they will release gases.
What an odyssey or an optima isn't going to do that a normal wet cell battery will is leak acid. They have what is more of a gel. That is why they can be put in any mounting position and can be put in applications where they are shaken and beaten. If the case ends up getting cracked there won't be acid all over.
There are plenty of DIYs and discussions on how to relocate your battery to the trunk. I will let you do your own research.