I used to have a bunch of motorcycles. I had one of these http://batterytender.com/product_info.php?products_id=2 hooked up to each bike over the winters and when I wasn't using them for more than a few weeks. Once I started using the Battery Tender(s) I never lost another battery. They work very well and supposedly only charge when needed as they have some sort of voltage circuitry to switch them on and off when needed. They aren't cheap but they work. RT

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