Description
Independent module-level power control without aging bottlenecks.
EcoFlow EF BD-5.1-S1 is a 5.10 kWh high-voltage LFP modular battery pack with an integrated 800 V DC-DC power stage, built-in aerosol fire suppression, and automated sub-zero self-heating, engineered for cable-free stacking under EcoFlow PowerOcean hybrid inverters.
Integrated 800 V DC-DC Power Stage
Each module regulates voltage independently, preventing older battery packs from dragging down newly added expansion modules.
3.3 kW Continuous Discharge per Pack
Delivers up to 3,300 W continuous power per single module, allowing a compact 2-brick stack to power 6 kW domestic loads.
Built-in Winter Self-Heating (-20 °C)
Internal thermal elements warm cells automatically before charging in unheated winter garages and outdoor alcoves.
Integrated Aerosol Fire Protection
Each pack includes factory-installed thermal-activated aerosol fire suppression for maximum residential peace of mind.
More product details
In traditional high-voltage battery stacks, connecting modules in rigid series means a single degraded cell limits the entire tower. The EF BD-5.1-S1 incorporates an active 800 V DC-DC converter in each pack.
- Active bidirectional DC-DC converter regulates output voltage independently.
- Allows adding new battery packs years later without capacity degradation or SOC imbalance.
- Internal busbar contacts pass power and communication directly between stacked modules.
EcoFlow PowerOcean
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Certified outdoor reliability down to -20 °C with active fire suppression.
Charging lithium batteries in sub-zero winter temperatures causes irreversible lithium plating. The EF BD-5.1-S1 includes integrated PTC heating elements and thermal aerosol fire suppression. Auto-heating warms battery cells to optimal charging temperatures using solar or grid power. Thermal-activated aerosol module suppresses thermal runaway in milliseconds without water. IP65 cast-aluminum casing certified for clean indoor utility rooms or sheltered outdoor walls (-20 to +50 °C).
Holds 4.8 kWh of usable LFP
Nominal is on the lead. Usable is 4.8 kWh at 95 percent depth of discharge. One brick, one figure.
Fits a 680 mm face
A single pack is 680 x 183 x 424 mm. Weight is 55.5 kg. The base and the junction sit on their own pages.
Pairs with HD-P1 and HD-P3
Single-phase stacks sit on the EF BD-B-S1 base. Three-phase stacks add the EF BD-JC-S1 on top of the same packs.
Technical data
Decentralized power regulation and active winter heating engineered for multi-year modular expansion.
5.1 kWh automotive-grade LFP battery module with integrated DC-DC converter and auto-heating.
Designed as the primary energy module for EcoFlow PowerOcean systems, each EF BD-5.1-S1 pack integrates an independent 800 V DC-DC converter, active fire protection, and auto-heating. It delivers up to 3,300 W continuous discharge per pack, enabling true multi-module parallel operation without aging-mismatch penalties.
- Modular Energy
- 5.10 kWh
- Output per Module
- 3.3 kW
- Sub-Zero Ready
- Auto-Heating
- External DC Conduits
- Zero
Power & Grid Output
- Maximum output power (W)
- 3.3 kW
Battery / Storage
- Battery nominal capacity (kWh)
- 5.1
- Battery usable capacity (kWh) at 95% depth of discharge
- 4.8
- Maximum input power (W)
- 2.5 kW
- Nominal voltage (V)
- 800
- Operating voltage range (V)
- 720 - 960
- Battery cell type
- LFP
- Dimensions W x D x H (mm), single pack
- 680 x 183 x 424 (+/-1)
- Weight (kg), single pack
- 55.5
Physical & Environmental
- Dimensions W x D x H (mm), single pack
- 680 x 183 x 424 (+/-1)
- Weight (kg), single pack
- 55.5
- Installation
- Floor stand / wall mounting
- Operating temperature (C)
- -20 to 50
- Cooling method
- Natural convection
- Noise emission (dB)
- <=35
- Protection level
- IP65
Project fit
Where this model fits.
Scenarios that show which projects the EcoFlow EF BD-5.1-S1 belongs in, what to verify before quoting, and when another model is the better pick.
Modular Storage Stacking for EcoFlow PowerOcean G1 Systems
Installing or expanding an EcoFlow PowerOcean single-phase or three-phase hybrid storage tower.
Stacking 1 to 3 modules vertically provides 5.1 kWh, 10.2 kWh, or 15.3 kWh; parallel multi-tower linking supports up to 45.9 kWh.
- Confirm this model against the adjacent rating in the same family
Documents
EcoFlow PowerOcean Single-phase datasheet (EU, EN)Product questions
What is the benefit of the built-in DC-DC converter in each battery module?
Eliminates battery aging mismatch and allows adding new modules years later. In traditional series batteries, adding a new pack to an older 3-year-old battery stack degrades the new pack to the capacity of the oldest module. With EcoFlow's pack-level DC-DC converter, each pack manages its own voltage and current independently, allowing seamless multi-year expansion with zero capacity loss.
What are the physical dimensions and weight of each module?
680 × 188 × 370 mm; approx. 59.2 kg. Each module measures 680 mm wide × 188 mm deep × 370 mm high and weighs 59.2 kg (approx. 130 lbs), featuring integrated side handles for a safe two-person lift.
System components
Recommended components
EF BD-5.1-S1 5.1 kWh LFP battery pack
Item number: DLK-ECOFLOW-EFBD51S1
The building-block pack for every PowerOcean stack, single- or three-phase; both HD-P1 and HD-P3 systems scale storage in 5.1 kWh steps of this same pack.
EF BD-B-S1 battery stack base unit
Item number: DLK-ECOFLOW-EFBDBS1
EcoFlow's own stack table lists EF BD-B-S1 x1 in every single-phase configuration (with EF HD-P1), the base unit any HD-P1 battery stack is built on.
EF BD-JC-S1 junction pack
Item number: DLK-ECOFLOW-EFBDJCS1
EcoFlow's own stack table lists EF BD-JC-S1 x1 in every three-phase configuration (with EF HD-P3), the junction pack any HD-P3 battery stack is built on.
Approved pairings
EcoFlow EF HD-P1-3.68K-S1Item number DLK-ECOFLOW-EFHDP1368KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P1-3K-S1Item number DLK-ECOFLOW-EFHDP13KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P1-4.6K-S1Item number DLK-ECOFLOW-EFHDP146KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P1-5K-S1Item number DLK-ECOFLOW-EFHDP15KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P1-6K-S1Item number DLK-ECOFLOW-EFHDP16KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P3-10K-S1Item number DLK-ECOFLOW-EFHDP310KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P3-12K-S1Item number DLK-ECOFLOW-EFHDP312KS1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P3-6K0-S1Item number DLK-ECOFLOW-EFHDP36K0S1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.
EcoFlow EF HD-P3-8K0-S1Item number DLK-ECOFLOW-EFHDP38K0S1Single-phase: EF BD-5.1-S1 x N plus one EF BD-B-S1 base. Three-phase: the same, plus one EF BD-JC-S1 junction pack, which the single-phase system does not use. Order the JC pack with every three-phase system. Max 45 kWh single-phase, 45.9 kWh three-phase.