The brain inside a Battery Tender® Junior 800 provides much more than a trickle charger could offer. It's completely automatic, can be plugged directly into the wall and left connected for long periods of time. The ISIMTM microcontroller constantly updates charge sequence for smooth transitions between charging steps. Lightweight, compact, fully automatic and very easy to use — especially in small spaces. It keeps your battery fully charged so that it is ready to go when you are.