Briggs & Stratton PHI 3.8 48V Specifications
Model | PHI-3.8-48-M |
Total Capacity | 3.87 kWh @ 100% DOD |
Nominal Voltage | 51.2 VDC |
Voltage Range | 48 VDC to 56 VDC |
Amp-Hours | 75 Ah |
Max Discharge Rate | 37.5 ADC (1.9 kW DC) |
Max Charge Rate | 37.5 ADC (1.9 kW DC) |
Surge Rate (10 min) | 80 ADC (4.1 kW DC) |
Operating Temperature | -4°F to 140°F (-20°C to 60°C) |
Cycle Life | 10,000+ cycles @ 80% DOD |
Round-Trip Efficiency | 96% |
Weight | 86 lbs (39.0 kg) |

Complete roof mounted solar systems engineered for durability and ease of installation. Our premium kits include IronRidge XR rail systems, compatible with all our solar panels and available for all roof types, with special options for tile, flat, and metal roofs at competitive wholesale pricing.
Briggs & Stratton PHI 3.8 48V Lithium Ion Battery
SKU PHI-3.8-48V
PHI™ 3.8 48V Lithium Battery

The PHI 3.8 48V battery system provides 3.87 kWh of energy storage in a standard 48V configuration, utilizing lithium ferro phosphate (LFP) chemistry that eliminates cobalt for enhanced safety and thermal stability. This 48V design delivers 1.9 kW of continuous power with 4.1 kW surge capability and works with Briggs & Stratton's high-performance Battery Management System (BMS) along with an accessible 100A DC breaker for comprehensive monitoring and control.
Engineered for compatibility with standard 48V inverter systems, this battery supports multiple power generation sources including solar, wind, grid, and generator systems. The modular design supports system expansion while maintaining compatibility with industry-standard 48V charge controllers and inverter systems commonly used in residential solar installations.
PHI™ 3.8 48V Lithium Battery Features
- Enhanced 48V Power: 4.1 kW surge capability and 1.9 kW continuous power delivery optimized for standard 48V residential solar and backup power systems.
- Onboard Safety Control: Accessible 100A DC breaker with overcurrent protection provides convenient system control and safety disconnect functionality.
- System Scalability: Modular 48V design allows parallel connection of multiple units to increase total system capacity while maintaining voltage compatibility.
- Residential Optimized: Standard 48V configuration integrates seamlessly with residential solar inverters and charge controllers following 2:1 sizing guidelines.
- Wide Operating Range: Extended -4°F to 140°F operating temperature range ensures reliable performance across diverse climate conditions.
Professional Installation Advantages
The PHI 3.8 48V battery delivers streamlined installation benefits that reduce material costs and simplify electrical design for professional installers.
- Compact 0.88 ft³ footprint with standardized 3/8" terminals for efficient space utilization
- Accessible external DC breaker eliminates separate combiner boxes and external disconnects
- Minimum 6 AWG cable requirement with standard bolt-on terminals for simplified wiring
- Efficient integration into existing electrical panels and conduit runs
- UL 9540 and UL 9540A certifications ensure code compliance for residential and commercial installations
- 10-year warranty provides long-term project confidence for installers and system owners

Briggs & Stratton PHI 3.8 48V Lithium Battery Review
The PHI 3.8 48V configuration represents the standard voltage choice for residential energy storage applications, providing optimal compatibility with 48V solar inverters and charge controllers. The 75 Ah capacity at 48V nominal delivers the same 3.87 kWh energy storage as the 24V model while operating at higher system efficiency due to reduced current levels. The 37.5 ADC continuous rating provides adequate power for residential backup applications while the 80 ADC surge delivers 4.1 kW for high-demand startup conditions.
The compact form factor and 86-pound weight facilitate installation in residential environments while the onboard 100A DC breaker eliminates external disconnect requirements. The extended temperature operating range and 10,000+ cycle life rating ensure reliable long-term performance in residential solar and backup power applications where daily cycling and seasonal temperature variations are common operational requirements.
Briggs & Stratton PHI 3.8 48V Features

Scalable to meet your energy needs
Modular design allows retrofit installation of additional PHI-3.8-M batteries to expand system capacity as energy requirements grow over time.

Onboard Over-Current Protection
Standard 100A DC over-current breaker with accessible external on/off switch safe and convenient system control without requiring enclosure access.

Industry-Wide Inverter Compatibility
Compatible with all industry-standard inverter charge controllers when proper 2:1 battery bank-to-inverter output sizing ratios are maintained.

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