Schaefer’s REX series of parallelable “4 in 1” inverters with UPS and “dual mode” battery charger provide 1500 or 3000-W of pure sine wave ac power. Applications include worldwide usage in recreational and industrial backup power applications. Due to the compact ultra-lightweight and rugged design, they are ideal for even the most extreme mobile environments in land, marine, or military applications. The “4 in 1” is built around a bi-directional converter that operates as an inverter or as a four-stage adaptive battery charger. User programmable limits allow operation of the loads while limiting the current used by the batteries for recharging.