Ok, The way to store battery's is fully charged, at 25 deg c, in a cool dry place,A fully charged lead acid battery will sit at 12.7v and agm will be 13v exsept dekas will sit a little lower, Buy yourself a good microprossesor controlled charger If you are only charging powersport sized batterys I recommend the C-Tek MXS0.8 and if you would like to charge car battery's too the C-Tek MXS5.0, Once every few months run the recond mode and you should be fine, I run deka Etx9 to ext 14 sized batterys in all 4 0f my ski's and In 3 years only replaced 1 etx 12 that I bought second hand to start with....
Lead acid batteries self discharge about 1% a day, agm batteries about 1% a week (not including any draw)
It's not uncommon for me to see batteries less then 6 months old totally dead because they wernt used or where left unattended and maintained especially in powersport applications where they may be used for a very small portion of the year, The bigger the battery the better and the longer it will last between charges... an thats also why couch batterys usually last longer too, bigger charging systems and bigger batteries!
Quick Tips
The cold will have an affect on your batterys performance but heat will kill it
Never run your starting batterys lower then 12v, Cranking batteries are designed for short high energy bursts and recharged strait away via alt and
sulfation can form alot easier at 1/2 charge
Leave lanyard unplugged, Some cdi's will draw power with lanyard in
keep your electrolyte topped up (critical in ski's if you have a maintainable lead acid it will leak a little bit everytime you ski rolls over and will leave battery plates exposed Promoting sulfation)
Buy a properly sized battery for your aplication for this go by the cca rating of a battery (the higher the better and the less of a cycle the battery will have to go through to start your engine the longer it will last)
Buy a cheep multi meter and keep an eye on your batterys voltage
