Sterling Power
Sterling Power BB1248120 – 12V to 48V DC-DC Battery Charger
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The Sterling Power BB1248120 is a step-up battery-to-battery (DC-DC) charger that takes a 12V input and charges a 48V auxiliary bank, delivering up to 28A at 57.6V. It suits high-voltage 48V house systems in campers, marine, and off-grid builds fed from a standard 12V vehicle electrical system.
Unlike a voltage-sensitive relay, the Saturn charger measures both current and voltage to move intelligently through bulk, absorption, and float, giving your batteries a correct, complete charge on every drive. Six preset profiles (Lead, AGM, and Lithium — two of each) plus custom profiles via the optional BBR remote suit virtually any chemistry. On this 48V model, charge target voltages are the 12V figures multiplied by four.
Charging Specifications
| Type | 12V → 48V battery-to-battery (DC-DC) charger, Saturn series |
|---|---|
| Input voltage range | 9–16V |
| Max output current | 28A at 57.6V |
| Max output power | ~1,613W |
| Max input current | 120A |
| Efficiency | 92–94% |
| Reverse / jump-start current | Up to 40A |
| Battery profiles | Lead I/II, AGM I/II, Lithium I/II (6 presets) + custom via BBR remote |
| Temperature sensor | TEMP1 included |
| Cooling | Thermostatically controlled, variable-speed fan |
| Protections | Self-recovering: under-voltage, input & output over-voltage, over-current, over-temperature |
| Recommended input cable / fuse | 35mm² (2AWG) / 150A |
| Recommended output cable / fuse | 6mm² (10AWG) / 40A |
| Dimensions | 270 × 130 × 73 mm |
| Weight | 1.8 kg |
| Operating temperature | −20°C to 60°C |
| Certifications | CE, UKCA |
| Warranty | 5-year return-to-factory |
Key Features
- Charges a 48V bank from a 12V vehicle system — up to 28A at 57.6V
- Bidirectional reverse-charge (jump-start assist) of up to 40A
- Six battery profiles plus custom charge profiles via the optional BBR remote
- Lithium-safe: a live output wakes most BMS units; charging is disabled below 0°C when the temp sensor is fitted
- Self-recovering protections and conformal-coated internals; CE/UKCA approved; 5-year warranty
Smart Alternator / Euro-6 Ready
Three engagement modes cover any vehicle: automatic voltage sense, ignition-feed control (for smart/Euro-6 alternators), and vibration sense (begins charging after detecting engine vibration — no ignition wire required).
Installation Notes
Requires a common, direct negative between the input battery, charger, and 48V output bank. The positive input must come from a circuit with a starter battery or Alternator Linearisation Device — not straight off a bare alternator. Fuse both input and output; recommended input cable is 35mm² (2AWG) with 150A fusing and output cable 6mm² (10AWG) with 40A fusing for runs under 3m.
Presented by Overland Kitted
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