Sterling Power
Sterling Power BB123665 – 12V/24V to 36V DC-DC Battery Charger
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The Sterling Power BB123665 is a 12V/24V-to-36V DC-DC (battery-to-battery) charger from the Saturn range. It automatically accepts a 12V or 24V input and steps it up to deliver a controlled, multi-stage charge to a 36V battery bank – ideal for 36V lithium or lead-acid systems in overland, marine, and specialist builds.
If you are new to dual-battery systems, the principle is straightforward: you cannot correctly charge a 36V bank straight from a 12V or 24V vehicle supply, and lithium in particular needs a controlled charge. The BB123665 does exactly that. Rather than a simple converter, it measures both current and voltage and steps intelligently through bulk, absorption, and float, giving your 36V bank a full, correct charge. It is bidirectional and lithium-safe, rated at 850W with 96% efficiency.
Charging Specifications
| Type | 12V/24V → 36V bidirectional battery-to-battery (DC-DC) charger, Saturn series |
|---|---|
| Input voltage | 12V / 24V autoselect |
| Input voltage range | 9–16V DC |
| Nominal output voltage | 36V |
| Output voltage range | 33–46V |
| Max output power | 850W |
| Max output current | Continuous output rating ≈20A at 43.2V (≈864W) |
| Max input current | Continuous input current ≈65A at 13.68V (≈900W) |
| Efficiency | 96% |
| Reverse / jump-start current | Bidirectional reverse-charge + jump-start assist – exact current available on the datasheet; contact us to confirm |
| Battery profiles | 6 selectable (Lead, AGM, Lithium) + custom via optional BBR remote |
| Temperature sensor | Included |
| Cooling | Thermostatically controlled variable-speed fan |
| Protections | Self-recovering: under-voltage, input & output over-voltage, over-current, over-temperature |
| Recommended cable / fuse | Available on the datasheet – contact us to confirm |
| Dimensions | 200 × 130 × 56 mm |
| Weight | 1.0 kg |
| Operating temperature | −20°C to +60°C |
| Certifications | CE, UKCA |
| Warranty | 5-year return-to-factory |
Key Features
- Steps a 12V or 24V vehicle supply up to a controlled, multi-stage 36V charge – input auto-selected
- 850W continuous output at 96% efficiency using buck-boost technology
- Lithium-safe with 6 selectable battery profiles (lithium, AGM, and lead) plus custom profiles via the optional BBR remote
- Bidirectional reverse-charge and jump-start assistance
- Smart-alternator / Euro 6+ compatible with included temperature sensor
- Self-recovering protections; CE / UKCA approved; 5-year return-to-factory warranty
- Suitable for EV auxiliary power management applications
- Features Sterling's named current-limiting technology to protect input and output circuits
Smart Alternator / Euro-6 Ready
Three engagement modes cover any vehicle: automatic voltage sense (engages once the alternator is charging), ignition-feed control (for smart / Euro-6 alternators), and vibration sense (begins charging once the internal accelerometer detects the engine running – no ignition wire required).
Installation Notes
Use a common, direct negative between the source battery, charger, and 36V bank. Take the positive input from a circuit fed by the starter battery (or an Alternator Linearisation Device) – not straight off a bare alternator. Rate the charger to no more than about 80% of your alternator's output. Fuse both the input and the output, and size cable and fuses to the current rating on Sterling's datasheet for your run length – contact us and we will confirm the exact figures for the BB123665.
Presented by Overland Kitted
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