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Sterling 'Pro Charge B' Waterproof Battery-To-Battery Charger - 12V/12V 25A

  (2 Reviews)
Price:  £214.51   (£178.76 Exc. VAT)

Product code:  P01902



Low stock, item being discontinued.

The Sterling 'Pro Charge B' 12/12V 25A Battery-To-Battery (DC-DC) charger offers fast, multi-stage charging of auxiliary batteries in automotive, marine and recreational vehicle applications.  It is waterproof to IP68 (can be fully submersed) and perfect for use in open boats as well as in vehicle applications where the mounting location is exposed to the elements.  A typical use for this product is for charging an auxiliary battery that powers an electric trolling motor. The alternator on the boat's main engine provides power to the DC-DC charger which, in turn, will charge the auxiliary battery whilst under-way, meaning it is ready to power the trolling motor when required.

Simple to install and configure, it provides a much deeper and faster re-charge than connecting directly to the alternator and is essential if you intend to re-charge a second battery in a modern vehicle where the introduction of  'smart' alternators has rendered traditional voltage sensitive relays (VSRs) redundant (please see download section below for more info). 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


  • Fully waterproof to IP68 - 100% epoxy-filled housing 
  • 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
  • Optional ignition feed
  • 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
  • 8 preset battery chemistry options to suit all battery types
  • Inidcator lights on front of unit
  • Quick and simple to install - pre wired with all cables and fuses
  • Designed in the UK

Further info

We recommend this charger for use in waterproof applications where the battery (or bank of batteries) to be charged is up to around 220Ah in capacity. 

  • Input nominal system voltage: 12V DC
  • Output nominal system voltage: 12V DC
  • Max. output voltage: 15V DC
  • Max. output current: 28A
  • System activation voltage: > 13.3V DC
  • System 'sleep' voltage: < 13.0V DC after 20 mins
  • Standby current draw: < 1mA
  • Input low voltage warning: 6.5V DC
  • Over-voltage trip: 16V (input or output)
  • Cable lengths: 1.5m
  • Ingress Protection rating: IP68 (full immersion to 1.5m for prolonged periods) 
  • Weight: 2.5kg
  • Overall dimensions: 230 (L) x 130 (W) x 50 (D) mm
  • Conforms to the following standards: E-Marked (suitable for OEM fitting)

Part Number:  BBW1212

Average Rating (2 Reviews):  
Write a Review and share your opinions!

Great charger
Thursday, 25 June 2020  | 

Used to recharge my leisure batteries in my truck that I use on my inverter. Does a great job recharging my batteries as I drive about

Battery-To-Battery Charger - 12V/12V 25A
Tuesday, 10 March 2020  | 

Saving up for second battery, will let know more later.