I need to get a new battery for one of my bikes and the vendor with the lowest price for the battery I want offers free shipping over $75 which is no problem as the battery I need is $92 but the battery on another bike is several years old and it's replacement would cost me $73 + $11 shipping if I purchased it separately after my existing battery on the other bike gives up the ghost. Both batteries are "AGM, maintenance free" and are shipped w/ separate acid packs that need to be added to the battery. My question is if I bought the $73 battery for the other bike now to combine the free shipping, would there be any "decay" if I kept the battery and acid separate in a dry, cool, dark environment over a year or more and added the acid when I needed to replace the battery?