I recently bought a newer, better battery. How do I store my 650 mah batteries as far as charging. I, of course, want to keep the batteries on hand just in case something goes wrong with my new batteries. Do the old ones need to be fully charged and then stored, completely drained and then stored, or just store them as is? I just don't want them to be useless if the unforseen problem exists. Not sure if there is a proper way of doing it or if it is really a problem either way. Thanks for any insight!