The Battery Tender® Junior High Efficiency is much more than a trickle charger. It has a brain. It's lightweight compact and fully automatic; very easy to use especially in small spaces. It will keep your battery fully charged so that it is ready to go when you are! This unit replaces the 021-0123 in the California market.
We use this item regularly on our BMW motorcycles. It includes a SAE connector that screws right onto the battery, and the charger DOES support the new AGM and GEL batteries that are installed OEM. It's designed as a battery maintainer, not for bringing one back from the dead however. Just plug your motorcycle in whenever you expect it to be sitting for quite a while, and you're golden.