I'm a revolving collector of sports cars and motorcycles. Some can sit as long as 6 months. For many years I have used the Schumaker 1.5 amp tender.

There are 12 in service in my garage right now. The oldest is eight years old. I even ran over one and it still works. They are $20 At Wal-Mart.

The proper use of a tender will extend the life of a battery from 2 to 5 times normal. To do that you leave it connected to the bike and unplug when you go for a ride and plug it back on when you return. The longest I went with a cycle battery was 8 years and it was going strong when I sold the bike.

I have never had a battery problem with this method period.

 

The Jr, same as most use are fine on mine too...just fired it up this week and its still going.

 

I'm using a Yuasa Smart Shot Automatic 12V 1.5 Amp Battery Charger.

I don't really do any long term storage. I use it like "lh4x4" stated.
I paid a bit more for it but it's feature loaded. You can read a review here: http://crfsonly.com/reviews/yuasa/yuasa-review.php
I have the "fused battery connector" D: in the pic above mounted on my battery. A very simple plug and unplug process.
Of all the maintainers/chargers I've used over the years this is the nicest I've had. Of course the price reflects that lol.

 

I use the battery tender for keeping the battery up to snuff during storage. I have the lead installed to the battery and is easy to connect to the tender for extended down times. When riding, I would like to have a cable that includes a power outlet (female, cigarette lighter type) one end and a battery tender plug on the other end. This would enable me to plug in the GPS, cell phone charger, etc..Does anyone know where I might find such a cable?

 

Wal-Mart has a plug that connects to the tender lead from the battery. I got one from there for the same purpose that you want.

 

Got one too but I made it. I had the parts laying around already.