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EcoFlow · extra battery

EcoFlow DELTA 2 Max Smart Extra Battery

2,048 Wh of LiFePO4, 42 lb, for the DELTA 2 Max, DELTA 3 and DELTA 3 Plus. $899 at EcoFlow, sold out when checked Oct 14, 2026: $0.44 for each watt-hour it adds. With the 2 EcoFlow allows, the DELTA 2 Max holds 6,144 Wh in all.

Adds

2,048Wh

Price

$899

Per Wh added

$0.44

Each watt-hour it adds costs less than the stations' own ($0.50 on the DELTA 2 Max, $0.58 on the DELTA 3 and $0.70 on the DELTA 3 Plus), so it is the cheaper way to more stored energy than a second station, which adds outlets and output instead.

From EcoFlow's published figures and our own arithmetic; we have not tested it ourselves.

Which stations take it

The most one station takes is EcoFlow's figure; a dash where its page gives none. Prices are both makers' prices added up, before cables.

EcoFlow DELTA 2 Max Smart Extra Battery on each station
StationMost per stationWith oneWith the mostStation and one battery
EcoFlow DELTA 2 Max2,048 Wh on its own 2 4,096 Wh 6,144 Wh $1,928
EcoFlow DELTA 31,024 Wh on its own – 3,072 Wh – $1,498
EcoFlow DELTA 3 Plus1,024 Wh on its own – 3,072 Wh – $1,618

Specs

EcoFlow DELTA 2 Max Smart Extra Battery: EcoFlow's figures
Capacity2,048 Wh
CellsLiFePO4
Weight42 lb (19 kg)
Cable, in the maker's words"Extra Battery Cable User Manual Warranty Card"
Where these figures come from

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Runtime is rated capacity × 0.85 ÷ watts. Check startup draw and connections separately. Prices are the maker's, with the day they were checked.