Sterling Power BB1225 Battery-To-Battery Charger - 12V/12V 25A

  (1 Review)
Price:  £169.99   (£141.66 Exc. VAT)

Product code:  P03589
Brand:  Sterling Power
Voltage  12-12V
Current Rating  25A



4 in stock

New for 2022/23, Sterling Power's revised Battery-To-Battery (DC-DC) chargers have been completely re-designed to make them simpler to use, more compact and easier to install, with a minimal amount of setup. They provide all the features of the previous generation but in a much more user-friendly package.

Compatible with both 'smart' and standard alternators, this 25A battery-to-battery charger is powered from your vehicle's alternator and delivers the correct charging voltage for your lead-acid or lithium battery. This new model features a vibration sensing mode, meaning that the charger will begin operating when the internal accelerometer detects vehicle movement. This eliminates the need to run a cable to supply an ignition or D+ alternator signal as is required on some other DC-DC chargers. An ignition feed option is still available should the vibration sensing not be suitable for your particular application.

This 25A model also features a bi-directional or 'reverse charging' feature whereby surplus current supplied to your leisure/house battery is passed to the starter battery to charge and maintain it. This is ideal when you are charging your leisure battery from shore/grid, solar, wind or generator power, and ensures that your starter battery is always kept in optimum condition.

The charger comes with a temperature sensor (optional fitment) that allows for temperature voltage compensation for lead-acid batteries, 0°C trip for lithium charging and high temperature trip protection. This unit also features a lithium battery BMS 'wake-up' function to enable your lithium battery to start accepting a charge if the BMS has put it into shut-down mode due to over-discharge.

An optional remote display not only allows you turn the unit on or off remotely, it also provides several additional advanced features such as custom charging profiles, current reduction and charging current and voltage display.

If you require a higher charge current (and your alternator can support it) then any of the units in this new charger range can operate in parallel (e.g. BB1225+BB1240 to provide 65A), providing you with redundancy and flexibility in power.

Sterling recommends connecting using 6mm² cable and 30A fuses (see related products below).


  • 4 stage DC-DC battery charging
  • 25A - current limiting
  • Bidirectional charging - enables starter battery trickle charging
  • 6 selectable charge profiles for all battery types including lithium
  • 95-98% efficient using buck boost technology
  • Compatible with both smart alternators (Euro 6) and standard alternators
  • 3 charger control modes: Ignition | Vibration | Voltage Sense
  • Automatically recoverable protection for various conditions (see 'Specifications' tab)
  • Multiple units can be wired in parallel to increase output

Further information

Important: Please ensure that your alternator is capable of providing sufficient charge output so that it is not over-worked (which may lead to premature failure). An alternator output of 35A+ is recommended.

  • Input voltage range: 9V-16V DC
  • Nominal output voltage: 12V DC
  • Max. rated output current: 24A @ 14.41V (approx. 345W)
  • Max. rated input current: 26A @ 13.68V (approx. 355W)
  • Efficiency: 98%
  • Standby current: 5mA
  • Under voltage protection: Yes (auto-recovering)
  • Input over voltage protection: Yes (auto-recovering)
  • Output over voltage protection: Yes (auto-recovering)
  • Over current protection: Yes (auto-recovering)
  • Over temperature protection: Yes (auto-recovering)
  • Operating temperature: -20 to +60°C
  • Cooling method: Variable low speed fan (thermostatically controlled)
  • Max. cable size: 6mm²
  • Overall dimensions: 123 (L) x 130 (W) x 56 (H) mm
  • Weight: 0.6kg
  • Approvals: CE, UKCA, E-marked

Part Number:  BB1225

Bar Code:  5060868551125

Average Rating (1 Review):  
Write a Review and share your opinions!

Easy to fit
13 November 2023  | 

Liked the fact that this B2B uses excess solar to charge starter battery if needed. There is also option to boost starter battery if below cranking voltage. Came with good instructions. Followed them and all is working as it should be.

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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