EcoFlow DELTA 2 Max Smart Extra Battery (Refurbished)Expandable capacity Increase the capacity of DELTA 2, DELTA Max and DELTA 2 Max with an extra 2048Wh. Triple power at up to 30% lower cost 2 6kWh expandable capacity to fit your energy storage needs. Add up to two DELTA 2 Max Smart Extra Batteries to gain a capacity of 6144Wh. And it's up to 30% more affordable than a power station of the same capacity. 10 year lifespan with an LFP battery Get 10 years of daily use until it hits 80% of its original