This is a matched pair: the BigBattery NEXUS 2 is a 48V LiFePO4 battery rated at 314Ah (16kWh), and the APEX-6.5K is a hybrid inverter rated for 6,500W continuous output. BigBattery designed the two to talk to each other directly, so you are not guessing at charge/discharge settings after installation.
Note: If you would like to review the manufacturer Product Specifications, Warranty, Brochure, etc., for this system, please refer to the "Resources (System Manuals and Warranty)" Tab above on this page.
Why This Pairing Matters
A battery and inverter that are not sized to each other is one of the most common causes of underperforming off-grid systems. Here, the NEXUS 2 is rated for 150A continuous discharge and 7.6kW of continuous battery power — enough headroom to fully support the APEX-6.5K's 6,500W continuous output without the battery working at its ceiling. The two units communicate over RS485 or CAN using a dedicated BigBattery/EG4 BMS protocol, so the inverter receives voltage, state of charge, temperature, and charge/discharge limits directly from the battery's BMS rather than relying on generic settings you'd otherwise have to configure by hand.
Battery Characteristics
Chemistry: LiFePO4 (Lithium Iron Phosphate). The NEXUS 2 ships in a floor-standing, IP54-rated enclosure suitable for indoor or outdoor installation, and carries an integrated BMS with multiple safety redundancies. Rated cycle life is more than 8,000 cycles.
Wiring & Configuration Limits
The NEXUS 2 battery bank can be expanded up to 15 units in parallel, with a maximum rated configuration of 241.5kWh. On the inverter side, up to six APEX-6.5K units can be paralleled for increased output, supporting single-phase, split-phase, two-phase, and three-phase configurations. The system supports solar, battery, grid-assisted, and generator-assisted operation.
NOT confirmed for series wiring of NEXUS 2 batteries — expansion described in source data is parallel only. Do not exceed 15 batteries in parallel or 6 inverters in parallel without a documented engineering review. This is not a starter/cranking battery and is not intended for automotive or marine cranking applications.
Pro-Installer Tip
Undersizing the inverter's charge current relative to the battery's BMS limits is a common field mistake, particularly when adding solar. The APEX-6.5K supports up to 140A of solar charging current, and the NEXUS 2 is rated for 150A continuous charge — confirm your total charge sources (solar + grid + generator combined) never exceed that 150A ceiling, or the BMS will lock out the pack to protect the cells. Sustained lockouts from repeated overcurrent events accelerate cell imbalance over time. Verify total charge current with a shunt-based battery monitor before commissioning, and set charge controller limits conservatively rather than at the rated maximum. LiFePO4 chemistry tolerates deep cycling well; BigBattery rates this pack for more than 8,000 cycles, consistent with routine operation in the 80-100% DoD range typical of lithium systems — do not treat it like a lead-acid bank that needs a 50% DoD ceiling.
Key Benefits
- 16kWh of usable LiFePO4 storage rated for more than 8,000 cycles
- 150A continuous discharge with a 270A one-second peak discharge rating for equipment startup
- Closed-loop BMS communication with the APEX-6.5K reduces manual configuration
- Dual independent MPPT solar channels with up to 140A of solar charging current
- 6,500W continuous / 13,000W surge inverter output with 10ms typical switching time
- Expandable to 15 batteries in parallel (up to 241.5kWh) and 6 inverters in parallel
Technical Table
| Spec | Value |
|---|---|
| Voltage | 48V |
| Battery Capacity | 314Ah |
| Battery Energy | 16kWh |
| Chemistry | LiFePO4 |
| Enclosure | IP54-rated, floor-standing |
| Max Continuous Discharge | 150A |
| Peak Discharge | 270A (one-second) |
| Continuous Battery Power | 7.6kW |
| Cycle Life | 8,000+ cycles |
| Inverter Continuous Output | 6,500W |
| Inverter Surge Capacity | 13,000W |
| Output Voltage | 120/240V split-phase |
| Switching Time | 10ms (typical) |
| Solar Input | Up to 10,000W combined, dual MPPT channels |
| Solar Charging Current | Up to 140A |
| Communication | RS485 or CAN, BigBattery/EG4 BMS protocol |
| Battery Warranty | 12 Years |
| Inverter Warranty | 5 Years |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
Designed to work together: BigBattery NEXUS 2 48V LiFePO4 battery + BigBattery APEX-6.5K hybrid inverter, matched 48V architecture, native BigBattery/EG4 BMS communication over RS485 or CAN. One NEXUS 2 supplies sufficient continuous power for the inverter's full 6,500W output, and inverter charging output stays within the NEXUS 2's 150A maximum charge rating.
NOT compatible with generic 48V batteries expecting standard lead-acid charge profiles without the dedicated BMS communication link. NOT intended for use with non-EG4/BigBattery inverter communication protocols unless independently verified. Grid and generator inputs are separate AC connections — this system does NOT include a transfer switch, solar panels, or PV wiring as part of this listing. [NEEDS VERIFICATION: whether an external cable kit or communication cable is included in the box.]
FAQ
Q: How many NEXUS 2 batteries can I add to this system?
A: Up to 15 in parallel, for a maximum rated configuration of 241.5kWh.
Q: Can I run this on 120/240V split-phase household power?
A: Yes. The APEX-6.5K supports configurable single-phase and split-phase output for standard 120/240V applications.
Q: What is the maximum solar input for the APEX-6.5K?
A: Up to 10,000W combined across two independent MPPT channels, with up to 140A of solar charging current.
Q: Does the battery need special cold-weather handling?
A: [NEEDS VERIFICATION] — low-temperature charging protection details are not specified in the provided manufacturer data for this listing.
Q: How many APEX-6.5K inverters can be paralleled together?
A: Up to six, for increased output capacity, supporting single-phase, split-phase, two-phase, and three-phase configurations.
Warranty & Support
Warranty: 12 years on the NEXUS 2 battery, 5 years on the APEX-6.5K inverter. Support: Lifetime USA-based tech support. Ships from Texas, USA. If you have questions about sizing this system for your load or expansion plans before you order, ask us — we always reply back.
