Battery Tender For Storage

Any battery in storage for winter or extended periods of time will give longer service life if a battery tender is used to maintain a full charge. This is the type that works well with a float mode with an output of .750 amps, also various accessories for the unit.
Battery Chargers and Accessories | Battery Tender Jr.




Here's a selection guide...
Batterytender.com - Home of All Your Charging Needs

Here's another source for extra cables too.
Battery Tender Jr 12 Volt 0.75 Amp Battery Charger: BatteryMart.com

Battery Tender ( The larger one 1.25 amps output )
A Battery Tender is similar to a trickle charger but will not overcharge your battery. Batteries in storage will lose a good portion of their charge in just 14 days! Standard trickle chargers can overcharge and permanently damage the battery. The Battery Tender puts an end to this worry. Connect the alligator clips to your battery terminals, plug it into a wall outlet, and that's it! It will maintain a 100% charge constantly: enough to ensure starting power, but not enough to boil away electrolyte and damage the plates. It even senses incorrect connections and will not charge if the polarity has been reversed.

Though I ride enough to keep my battery charged,I keep the Battery Tender attached to my bike when not riding for periods longer than a few days. My past bikes have never left me stranded with a dead battery. You can even make it easier to connect by wiring a cigarette lighter socket to your battery and mounting it somewhere on the bike, and a male connector to the charger's clips. This setup even doubles as a lighter if you have the correct one.This inexpensive modification now allows you to charge your bike without pulling the seat off each time.
What I use is an inexpensive two prong chrome connector, available in any boating supply store, mounted to the bike for the purpose of a connection, if it doesn't allready come with the pigtail when you buy the charger.