Sterling battery to battery charger 12V/24V to 48V / 65A | BB124865 | Charging booster

Battery to battery charger 12V/24V to 48V - Charging booster - Intelligent battery charging

for lead, AGM and lithium batteries | compatible with Smart Alternator / Euro 6 | with recharging function & jump start

The Sterling Power BB124865 is a cleverly designed and powerful solution for anyone who wants to charge their 48V battery system reliably and efficiently from a 12V or 24V power source while driving.No complicated wiring is required, you do not need to connect the charger directly to the alternator or manipulate the electronic control units (ECUs). Simply connect the charger between the on-board battery and the supply battery. The charging booster is not only used in vehicle installations, but can also be used in 12V/24V stand-alone systems to charge a 48V battery system.

Despite its compact design, this device combines state-of-the-art charging technology with versatile functions that go far beyond simple charging and can therefore be used for demanding requirements in a wide range of applications. For example, you can effectively use the alternator in your motorhome or caravan to charge your supply battery or have different voltage levels work together on your boat or yacht.

The high-quality workmanship and sophisticated cooling ensure reliable continuous operation even under demanding conditions and its compact dimensions make it easy to install, even in confined spaces.

Note: When connecting the B2B to the starter battery, please ensure that your alternator provides sufficient charging power so that it is not overloaded.

What starting options does your Sterling Power BB124865 offer?

Your B2B charger is very flexible in this respect. It offers you three intelligent operating modes that can be optimally adapted to different vehicle configurations and usage scenarios. Select the start option that suits your application:

Automatic mode:
This mode represents the most uncomplicated and quickest installation method for your charger, as no additional control cables need to be laid. However, this operating mode is not the most effective solution in all vehicle situations. Particular challenges arise in modern vehicles with intelligent alternator control (regenerative braking) or with unstable input voltage, as can typically occur with Euro 6 engines and newer generations of engines. To activate the B2B, a voltage > 13.5V in the 12V vehicle electrical system and > 27V in the 24V vehicle electrical system is required at the input connection. This voltage is reached when the alternator or another voltage source charges the starter battery. If the voltage drops below 12.8 V or 25.6 V again when the engine is switched off, the device switches off automatically and switches to the energy-saving idle state to prevent the starter battery from discharging.

Ignition signal / D+ mode (requires 12V signal supply):
In this mode, the B2B is controlled on the basis of an ignition signal (terminal 15) or D+. As soon as the signal line is active (voltage range 5V to 32V), the device switches on and starts charging. This operating mode offers you the most direct and precise on/off control of the charger.

The charger continuously monitors the starter battery and switches off automatically when 11 volts are reached in the 12V system or 22V in the 24V system - even when the ignition or D+ signal is active - in order to protect your starter battery. Caution: When the ignition is switched on without the engine running, the B2B can discharge the starter battery, as neither the alternator nor the charger will recharge. This mode is therefore best suited for vehicles in which the ignition signal is only active when the engine is running.

Vibration sensor mode:
To use this mode, the corresponding slider on the device must be set to "on". This activates the internal vibration sensor and the B2B detects vibrations, such as the engine starting, and begins charging. In our test, we found that the internal vibration sensor is quite sensitive. The B2B monitors the input battery and switches off after 2 minutes if the voltage does not increase. This mode essentially functions like an ignition signal and was developed so that no ignition cable has to be laid or if no D+ signal is available.

Why should you adjust the current limit?

In the default setting, the charge booster operates at 100% charging power, this can be reduced to 85% or 65%. Examples of why you might want to reduce the power:

• If there is sufficient solar charging in good weather, you can save fuel by reducing the B2B power.
• If the alternator is not powerful enough to recharge the starter batteries sufficiently
• Your battery supplier may recommend charging your battery at a lower amperage.
• Future-proofing. Install a high-capacity B2B now and be prepared for future upgrades to the alternator or battery system.

Can I also integrate the Sterling Power BB124865 into a solar system?

Yes, you can. Whether your 12 or 24 volt battery system is powered by an alternator or a solar system is irrelevant for the use of the B2B. A classic solar system has different voltages depending on its size and type. Smaller systems, such as those used for balcony power stations or for operating lights in simple huts, often work with 12 V or 24 V direct current (DC). Here you use 12 or 24 volt battery storage systems to store solar energy.

With this battery to battery charger, you can also use a 48V battery system by using the B2B to store the solar energy generated from your existing 12 or 24 volt battery system in a 48V battery system. This means that no surplus energy is lost and you have the option of connecting 48V consumers.

Possible application example - 12V base system with 48V storage and bidirectional energy management
Many older stand-alone systems work with 12V battery systems, which enable the operation of 12V consumers such as LED lighting, a 12V water pump, a radio or USB ports.

In this concept, the established 12V system serves as the main supply with direct solar charging, while a 48V battery storage system acts as a highly efficient storage unit for excess energy. By using a battery monitor such as the BMV-700 battery monitor from Victron, you can precisely control the level of storage utilisation reached in the 12V system at which the surplus energy is transferred to the 48V storage system. This concept also allows you to connect 48 V consumers, such as a 48 V air conditioning system or our pure sine wave 2200 W 48 V inverter with RCD, via the 48 V battery system. Due to the smaller cable cross-section, it is more efficient than a 12V inverter.

Please contact us to find the best solution for you. We look forward to hearing from you.

Scope of delivery

• 1 x Battery to battery charger 12V/24V to 48V / 65A | BB124865 | Charging booster
• 1 x temperature sensor
• Of course, you can also obtain operating instructions in German from us in the download area.

Warranty period

• 2 years warranty

Further helpful tips can be found in our FAQ questions/answers page under the following link FAQ.

Battery to battery charger 12V/24V to 48V / 65A