Sterling Power BB1270 12V 70A Bidirectional DC-DC Battery Charger

The Sterling Power BB1270 is the benchmark DC-DC charger for overland builds, truck campers, and off-road rigs running lithium house banks. At 70A input and 60A output, it delivers fully regulated, 4-stage alternator charging with the full intelligence of Sterling's Saturn series — the same platform trusted in expedition vehicles and commercial marine installs worldwide. We typically recommend the BB1270 as a strong starting point for builds in the 100–400Ah range — though the right charger always depends on your alternator capacity, your loads, and how you actually use the rig.

This isn't a relay or a basic isolator. The BB1270 reads your battery's state of charge and applies the correct bulk, absorption, and float voltages for your specific chemistry. Six preset battery profiles cover Lead I and II, AGM I and II, and Lithium I and II, so you're never pushing a generic voltage into a lithium bank. A low-temperature cutoff protects lithium cells from charging in freezing conditions, and six self-recovering protection circuits handle over-voltage, under-voltage, over-current, and over-temperature events automatically.

Bidirectional reverse charging is standard. When your house bank climbs above 13.2V (13.5V on lithium profiles), the BB1270 automatically feeds up to 20A back to the starter battery to maintain it at a healthy 13.4V — so if solar is looking after your house bank while the rig sits, your starter is looked after too. If the starter ever gets too low to turn the engine over, Jump Start Assist mode forces the reverse charge to run for 20 minutes to get you back in action.

The BB1270 is fully parallelable with other Saturn series units. Running a larger lithium bank or want built-in redundancy? Two BB1270s in parallel gives you 140A total — and if one unit ever goes down, the other keeps charging. No single point of failure on your electrical system.

Installation is clean and straightforward — any mounting orientation works, and the thermostatically controlled fan only spins up when the unit needs it.

Key Specs:

• Input voltage range: 9–16V
• Rated input current: 70A
• Rated output: 60A at 13.8V
• Reverse charge current: 20A
• Efficiency: 92–94%
• Dimensions: 200mm × 130mm × 56mm
• Weight: 1.0 kg
• Recommended input cable: 16mm² / 6AWG
• Recommended input fuse: 80A
• Recommended output cable: 16mm² / 6AWG
• Recommended output fuse: 80A
• Certifications: CE, UKCA, E-Mark
• Cooling: thermostatically controlled variable-speed fan
• Compatible: lead acid (AGM, gel, flooded), lithium LiFePO4

Compatible with smart/variable alternators (Euro 6/7+). Ignition feed or vibration sense activation modes. Optional BBR remote available for display monitoring, custom charge voltage adjustment, and output current limiting.