OutBack Power NorthStar Battery's NSB 40FT BLUE+ batteries are front-terminal rack-mount batteries made with thin plate pure lead (TPPL) grids and carbon enhanced negative plates increasing life in float, cycling and PSoC use. These are built for deep cycling and partial state of charge use, ideal for off grid or self-supply, as well as backup systems. They have very low self-discharge for up to 24-month shelf life, and high charge and discharge efficiency. These are rated for 2,050 cycles at 50% depth of discharge. Maximum charge rate is not limited.