I really can't see any point to installing a 24 volt battery because you would blow crap up!

What he meant by "depends if you want 12 or 24volt" was if you put them in parallel, you'll get 12volt, and it'll last ages, or in series you'll get 24v..... i can only see that as a bad thing.

im pretty sure dry cells dont give off any combustible gas. just like rechargebale AA's and camera batteries etc. sum1 correct me if im wrong