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Mastervolt

83012031

BI 1203-S Load Distributor

The Mastervolt BI 1203-S load distributor is a reliable solution for distributing current between three 12/24VDC battery banks. Part of the conventional diode-based BI range, this "S" model includes diode compensation for optimized charging via alternator (120A max) or charger (80A max). It is supplied with the distributor and its integrated connection terminals.

Price excl. import taxesBenefit from the professional rate

£113.39 GBP

£113.39 GBP ~~£151.17 GBP~~

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Prices exclude import taxes. DAP delivery: import taxes are paid on delivery.

Available in stock

Free pickup point from €150 in France
Pickup at Skysat possible

Custom installation

Trust Skysat to install the equipment on board

Request a quote

Installers near you

thanks to our network of approved installers

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Support service

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Technical specifications

Nominal voltage	12/24 V
Amperage	120.0
Number of circuits	3.0
Number of poles	3
Supported battery banks	3.0
Battery switch type	Diode load distributor
Battery switch control method	Diode
Breaker reset type	None
Circuit breaker type	None
Circuit protection method	Diode
DVSR continuous current rating	0.0
Mounting type	Wall mounting
IP rating	IP20
Display type	None
Wired network	None
Certifications	CE
Maximum cable lug size	6.35 mm
Operating temperature range	-20 to +60 °C
Dimensions (W x H x D)	207 x 140 x 80 mm
Weight	1.3
Product type	Battery combiner / load distributor

Detailed description

The Mastervolt BI 1203-S load distributor is a robust and reliable solution designed to optimize energy management on board vessels equipped with 12/24 VDC systems. It efficiently distributes charging current from an alternator or charger to up to three independent battery banks while ensuring electrical isolation to prevent mutual discharge. This model is ideal for installations requiring stable power supply and enhanced battery protection.

Technology and performance

Part of Mastervolt’s BI range, the BI 1203-S uses conventional diode technology. It differs from models without the "S" suffix by integrating a compensation diode. This feature is critical as it automatically compensates for the voltage drop (approximately 0.6 V) inherent to diodes when the distributor is paired with Mastervolt Mass battery chargers or Alpha Pro charge regulators. This ensures batteries receive their full charging voltage, optimizing their lifespan and performance. In comparison, other Mastervolt solutions like the Charge Mate focus on connecting/disconnecting two batteries, while the Battery Watch provides monitoring and a main switch function. The BI 1203-S handles a maximum output current of 80 A for a charger and 120 A for an alternator, with an input voltage range of 6 to 50 VDC, and ground isolation exceeding 500V at 60Hz.

Design and installation

The Mastervolt BI 1203-S features a compact design with dimensions of 207 x 140 x 80 mm and a weight of 1.3 kg, making it easy to integrate into confined spaces on board. Its construction is tailored for marine environments: it is made from fully corrosion-resistant materials, includes an aluminum heat sink, and electronic components encapsulated in synthetic materials. This robustness ensures exceptional durability in the most demanding maritime conditions, with an operating temperature range from -40 to +120°C. Installation is simplified by synthetic end plates with terminals, and sturdy threaded connectors with nuts and locking washers that guarantee reliable and quick connections. For "S" models, connecting a current source probe (sense-connection) is essential to activate automatic voltage drop compensation.

Documentation

Type	Nom
	FR - Fiche technique - Répartiteur de charge BI 1203-S
	NL - Manuel d'installation et d'utilisation - Répartiteur de charge BI 1203-S

Expert opinion

Pol CONIN

Digital Manager

« Technical analysis: Mastervolt BI 1203-S load distributor with diode compensation »

The Mastervolt BI 1203-S is a proven solution for managing multiple battery banks on board. As a conventional diode isolator, it provides essential electrical isolation between up to three battery groups, preventing mutual discharge. Its ability to handle a maximum alternator current of 120 A and a charger current of 80 A makes it suitable for medium to large marine electrical systems.

The key advantage of the "S" version lies in its integrated compensation diode. This feature is crucial for maintaining optimal charging voltage across each battery bank. When paired with Mastervolt Mass chargers or Alpha Pro charge controllers, the BI 1203-S automatically compensates for the voltage drop (approximately 0.6 V) inherent to diodes, ensuring batteries receive their full charging voltage without manual adjustment of the source.

Its robust construction, featuring an aluminum heat sink and encapsulated components, ensures excellent durability and resistance to corrosive marine environments. Installation is straightforward thanks to clear terminals and reliable threaded connectors, though connecting the "sense" line is mandatory to fully utilize voltage compensation on "S" models. It is essential to follow cable distances and cross-sections to optimize performance and minimize heat buildup under high loads.

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BI 1203-S Load Distributor

£113.39 GBP

£113.39 GBP ~~£151.17 GBP~~

Frequently Asked Questions

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What is the Mastervolt BI 1203-S load distributor?

The Mastervolt BI 1203-S charge distributor is a robust and reliable device designed to optimize energy management aboard vessels. It efficiently distributes charging current from an alternator or charger to multiple independent battery banks.

What is the main function of the BI 1203-S charge distributor?

The primary function of the BI 1203-S battery splitter is to divide the charging current between different batteries or battery banks with the same nominal voltage. It ensures electrical isolation of the batteries, preventing them from discharging each other.

What is the difference between the BI 1203-S model and a BI splitter without the "S" suffix?

The main difference lies in the integration of a compensation diode on models with the "S" suffix (such as the BI 1203-S). This diode automatically compensates for the voltage drop (approximately 0.6 to 0.7 V) inherent to diodes, ensuring that batteries receive their full charging voltage, especially when paired with Mastervolt Mass chargers or Alpha Pro charge controllers.

How many battery banks can the BI 1203-S battery distribution panel manage?

The Mastervolt BI 1203-S battery combiner is designed to manage up to three independent battery banks.

What technology is used in the BI 1203-S load distributor?

The BI 1203-S charge distributor is based on conventional diode technology.

What are the physical dimensions of the BI 1203-S splitter?

The dimensions of the BI 1203-S load distributor are as follows:

- Height: 207 mm (8.1 in)

- Width: 140 mm (5.5 in)

- Depth: 80 mm (3.1 in)

What is the weight of the BI 1203-S load distributor?

The BI 1203-S load distributor weighs 1.3 kg (2.9 lbs).

What is the maximum current output for a charger and an alternator with the BI 1203-S?

The BI 1203-S splitter can handle a maximum output current of:

- 80 A for a battery charger.

- 120 A for an alternator.

What are the manufacturing materials of the BI 1203-S splitter?

The BI 1203-S splitter is made from materials fully resistant to corrosion. It features an aluminum heat sink and its electronic components are encapsulated in synthetic materials for enhanced robustness and durability.

Where should I install the BI 1203-S charge distributor for optimal performance?

For optimal performance, the BI 1203-S load distributor must be installed as close as possible to the power source (charger or alternator) and the batteries. It should be mounted in a well-ventilated environment, preferably on a flat metal surface, with the cooling fins positioned vertically. This helps dissipate the heat generated by high currents.

What safety precautions should I take before installing the splitter?

Before any installation, ensure the power source output is disconnected (power off). Also check that no consumers are connected to the batteries to avoid any hazardous situation.

How to connect the positive terminals of the batteries and the power source to the busbar?

Connections are made as follows:

- Connect the positive output of the power source (charger or alternator) to terminal A of the busbar. Terminal A is the longest bolt.

- Connect the positive connections of the battery banks to terminals 1, 2, and 3 of the busbar, respectively.

How to connect the compensation sensor (sense) to the BI 1203-S splitter?

For models with a compensation diode such as the BI 1203-S, connect the current source probe (sense) to the S terminal of the busbar. The S terminal is the thinnest bolt. This connection enables automatic regulation of the output voltage.

Should the negative connections of the batteries and power source be connected to the busbar?

No, the negative connections of the battery banks and the power source (charger or alternator) must be connected directly to a common ground point, not to the load distribution panel.

With which Mastervolt equipment is the BI 1203-S distributor specifically designed to operate?

The BI 1203-S splitter is specifically designed to operate optimally with Mastervolt Mass battery chargers and Alpha Pro charge controllers. These devices feature an automatic voltage drop compensation function that leverages the BI 1203-S's compensation diode.