Expand your system's capabilities by increasing its capacity with the DELTA 3 Smart Extra Battery for Max Plus/Ultra Plus from EcoFlow. For existing owners of DELTA 3 Max Plus and Ultra Plus systems, this battery adds an additional 2048Wh of power capacity to your home. Internally, the power is provided by long-lasting LFP battery cells. The stackable design makes it easy to physically incorporate the new battery with your existing batteries, and hookup is designed to be plug and play.