whats the differents mahs means on 18650 batteries..? I just bought a variable volt and have to get 18650 battery...when I go over to this site I want to buy them from they have all different mahs ratings on there batteries..does the mahs matter? Is the mahs giving the battery more power....I understand it has to be a LI-Ion battery and protected it's just the different mahs screwing me up. Thank you