Sterling 'Pro Batt Ultra' Battery-To-Battery Charger - 24V/12V 35A

Price:  £343.01(£285.84 Exc. VAT)

Product code:  P01455


In stock  

In stock

Note: Cables not included. Please download installation instructions (see link below) to determine correct cable size.


The Sterling 'Pro Batt Ultra' 24V/12V 35A Battery-To-Battery charger offers fast, multi-stage charging of auxiliary batteries in automotive, marine and recreational vehicle applications where the main battery bank is 24V and the bank to be charged is 12V (e.g. trucks and horseboxes)  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


  • 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
  • No ignition feed required in 99% of installations
  • 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, plus user-customisable profile
  • Comprehensive front panel display
  • Quick and simple to install (Batt IN, Batt OUT and NEG/GND) - cables not included
  • Dynamic thermal charging via IP68 waterproof temperature sensor (included)
  • Night time setting for silent running (no fan) at 50% power
  • Fire-proof plastic enclosure

Designed in the UK


  • Input nominal system voltage: 24V DC
  • Output nominal system voltage: 12V DC
  • Current limit: 35A (output limited to this value, input unlimited)
  • Voltage output: Variable dependent on selected charging profile
  • Cooling method: Variable speed fan
  • Cable connection: Screw clamp terminals (max. cable size 16mm2)
  • Ingress Protection rating: IP21 (drip proof - when mounted vertically) 
  • Weight: 1.9kg
  • Overall dimensions: 196 (H) x164 (W) x 102 (D) mm
  • Fixing hole dia: 4.5mm
  • Conforms to the following standards: E-Marked (suitable for OEM fitting)


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