(Duh I didn't until today) If you use your bike less than every 3 months, the battery plates will begin to Sulphate and it's capacity to hold charge will deteriorate. To combat this you should use a trickle charger - mine here is a cheapo from Maypole. Plugged into the mains it gives a 12Volt 500mA output, with a 800mA maximum current.
You can leave it clipped on to your battery in situ, on the bike (presuming it sleeps in a garage) and it will cut out when it's had it's fill. (With my now deceased battery, the little red warning light on the charger only came on briefly before going out when plugged in. This was a warning I didn't appreciate that it wasn't holding its charge).Previously I'd only ever used this beefy Ferm charger once a year if my battery was dozy usually come winter. It says 12V 6A so I always presumed (wrongly) it was fine for the likes of my CCM battery which is 12V 8A. But designed for car batteries with a much higher cranking Amps, it's way to Frankenstein for a small bike battery, and if you leave it on it will start to fry the battery - so I've been killing my batteries in their sleep rather than resuscitating them. BPDoes electricity completely baffle you? Do you look at wiring diagrams and trip your brain cells? All the answers to life's mysteries are covered in this magical book by Arthur C. Clarke