Just like the Plus model, the Battery Tender Junior is a fully automatic battery charger that has a "float" characteristic which allows for it to generally be left attached into the battery terminals, charging because it depletes and only as required. Nonetheless, this charger is a bit less expensive than https://hukums.com/products/elephant-2-hp-100l-170lpm-lubricated-air-compressor-copper-winding-with-motor-6-months-warranty-ac-100