Sterling Power BB484830 48V to 48V 30A DC-DC Battery Charger

The Sterling Power BB484830 solves a problem that becomes critical as 48V systems scale up: how do you safely charge one 48V battery bank from another without risking catastrophic current flow between banks at different states of charge? The answer isn't a relay or a direct connection — it's the BB484830.

Connecting two independent 48V banks directly is genuinely dangerous. A flat 15S LiFePO4 battery sitting at ~40V connected to a full 16S bank at 54V creates a massive voltage differential that can produce uncontrolled current surges, trip BMS protection circuits, and leave you with no charging path at all. The BB484830 eliminates that risk entirely — it isolates the two banks and charges between them at a controlled 30A with the correct 4-stage charge profile for your battery chemistry. Six preset profiles cover Lead I and II, AGM I and II, and Lithium I and II, with a low-temperature cutoff that protects lithium cells in freezing conditions. Six self-recovering protection circuits manage over-voltage, under-voltage, over-current, and over-temperature faults automatically.

A practical example: a large 48V rack battery used as a stationary storage bank can safely charge smaller 48V packs used in vehicles, electric boats, or robotics platforms — all without direct bank-to-bank connection or manual voltage matching. The BB484830 handles the differential and applies the right charge voltages regardless of where each bank sits in its state of charge.

Bidirectional reverse charging is standard. When the output bank is above the trigger threshold and the input bank is below it, the BB484830 automatically feeds up to 10A back in the reverse direction — keeping both banks in balance when solar or another charge source is maintaining one side. Jump Start Assist mode can also be manually triggered to force reverse charge for 20 minutes if needed.

Activation is flexible — ignition feed accepts any signal between 8–80V, making it compatible with a wide range of vehicle and stationary system voltages. A selectable vibration sensor mode engages the unit automatically when in motion, eliminating the need for a wired ignition signal in mobile applications.

Key Specs:

• Input voltage range: 39–65V DC
• Input current rating: 28–39A (varies with input voltage)
• Output voltage range: 38–62V DC
• Rated output current: 30A
• Reverse charge current: 10A
• Continuous output power: ~1,400–1,700W
• Efficiency: 95–98%
• Quiescent current: 5mA
• Operating temp: -20°C to 60°C
• Dimensions: 270mm × 130mm × 73mm
• Weight: 1.8 kg
• Certifications: CE, UKCA, E-Mark
• Cooling: thermostatically controlled variable-speed fan
• Compatible: lead acid (AGM, gel, flooded), lithium LiFePO4 (15S and 16S)

Ignition feed accepts 8–80V signal input. Vibration sense mode available for mobile applications without ignition feed wiring.