Sterling BBW12120 'Pro Batt Ultra' Waterproof Battery-To-Battery Charger - 12V/12V 120A

Price:  £459.13   (£382.61 Exc. VAT)

Product code:  P01405
Brand:  Sterling Power



Awaiting new stock.

Note: Positive cables not included. Please download installation instructions to determine correct cable and fuse sizes.

The Sterling 'Pro Batt Ultra' Waterproof 12V/12V 120A BBW12120 Battery-To-Battery charger offers fast, multi-stage charging of leisure/auxiliary batteries in automotive, marine and recreational vehicle applications.  Simple and quick to install and configure, it offers a much deeper and faster re-charge than connecting directly to an alternator and is essential if you need to re-charge a second battery in a modern vehicle where the introduction of  'smart' alternators has made traditional voltage sensitive relays (VSRs) redundant (please see download section below for more info). This charger is waterproof to IP68 with encapsulated electronics so is ideal for installation in engine compartments and other areas where moisture is present.

Smart alternators are ECU controlled and their voltage output varies continuously throughout a journey. Often the voltage is too low to provide any charge to the batteries via a VSR and at other times the voltage is very high (with regenerative braking systems) which can damage sealed, AGM & Gel batteries.

Sterling Battery-To-Battery chargers take the variable voltage output from the alternator and boost or reduce it to maintain a stable voltage output according to a multi-stage charging profile, providing a safe, controlled and fast charge for your auxiliary battery. Another benefit is that current flow is limited by the charger's current rating, eliminating potentially damaging high in-rush currents to deeply discharged batteries and allowing the use of smaller connecting cable compared with VSR split charge systems (which need to handle the max. alternator output).  Importantly, once the engine is turned off the charger automatically isolates the starter and leisure batteries from each other to prevent accidental discharge.

Compatible with the following manufacturer's technologies plus many other Euro 5/6 + vehicles that use smart alternators & regenerative braking.

® Trademark of Mercedes Benz ® Trademark of Volkswagen ® Trademark of Vauxhall ® Trademark of Ford


  • Suitable for all battery types (wet lead acid open and sealed, AGM, gel, lithium and calcium).
  • No connection to alternator required (no warranty issues)
  • No adverse effect on ECU
  • Around 5x faster charging than traditional split charge systems
  • Multi-stage profile for a deep charge and long battery life
  • Solves Euro 5/6+ smart alternator and regenerative braking issues that make VSRs redundant
  • Input voltage boost/reduction for stable and correct charging profile
  • Automatic battery isolation/separation with engine off
  • 9 preset battery chemistry options to suit all battery types
  • 6 LEDs showing charger status
  • Quick and simple to install - Batt IN & OUT cables not included
  • Hard-wired and fused negative cable
  • Dynamic thermal charging via IP68 waterproof temperature sensor (included)
  • Designed in the UK
  • Input nominal system voltage: 12V DC
  • Output nominal system voltage: 12V DC
  • Current limit: 120A (output limited to this value, input unlimited)
  • Voltage output: Variable dependent on selected charging profile
  • Cooling method: Variable speed fans
  • Cable connection: M8 studs accepting 8mm ring terminals
  • Ingress Protection rating: IP68 (dust-tight and protected against full submersion). Fans are P55 and designed to be easily replaceable.
  • Weight: 2.1kg
  • Overall dimensions: 174 (L) x 156 (W) x 119 (H) mm
  • Fixing hole dia: 4mm
  • Conforms to the following standards: E-Marked (suitable for OEM fitting)

Part Number:  BBW12120

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Sterling Power

Sterling Power Products is at the forefront of battery charging and power management technology for both the professional and recreational consumer, with many years’ experience. Providing a vast range of products and solutions, this UK-based company uses its award-winning charging technology to minimise re-charge times and maximise service life by ensuring the optimum charging profiles for your battery system. Sterling Power Products is an extremely well known and trusted brand within the marine electronics market and offers a large range of DC-DC charging solutions for the automotive sector.

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