Battery Tender ® Junior’s lightweight, compact size makes it ideal for those hard-to-fit spots. The trickle charger with a brain will assure batteries are maintained after charging and always ready to go! Fully automatic two-stage lead-acid battery charger. Perfect for all lead-acid, sealed maintenance free and gel cell batteries. After reaching peak 14.4 VDC, the charger automatically switches to 13.2 VDC float voltage.