Overview

The Victron Energy BMS400100300 is a smallBMS NG battery management system for Victron Lithium NG batteries, built to protect an onboard lithium bank by controlling charge disconnect, load disconnect, and low-voltage pre-alarm functions. It works with Lithium NG battery systems arranged for 12V, 24V, or 48V service, with an operating voltage range of 8 to 70 Vdc.

This unit is a good fit for compact marine DC systems where the battery bank does not need VE.Bus communication. It connects with VictronConnect over built-in Bluetooth for monitoring, configuration, and firmware updates, and it receives state of charge and current data directly from compatible Lithium NG batteries, so a separate SmartShunt is not required for those values.

The enclosure measures 106 x 42 x 23 mm and uses a matt black ABS housing. Its IP20 electronics rating means it belongs in a dry, protected electrical space such as a distribution locker, battery compartment, or inside a console, away from bilge water, deck washdown, and salt spray.

Key features

• For Victron Lithium NG batteries only; not compatible with Victron Lithium Battery Smart batteries.
• Supports Lithium NG banks configured for 12V, 24V, or 48V systems.
• Built-in Bluetooth works with VictronConnect for setup, monitoring, firmware updates, and quick status checks.
• Load disconnect output can control compatible remote on/off inputs to help prevent deep discharge.
• Charge disconnect output can stop compatible chargers when cell overvoltage or overtemperature is detected.
• Pre-alarm output gives a visible or audible warning before load disconnect occurs during low-voltage conditions.
• Remote on/off terminals allow the charge and load disconnect outputs to be switched from an external control point.
• Blue and red LED indicators show Bluetooth status, warnings, and errors at the unit.
• Compact 106 x 42 x 23 mm size helps it fit into crowded marine electrical panels and battery installations.
• IP20 electronics rating suits protected interior mounting rather than exposed deck, cockpit, or bilge locations.

Compatibility and fit

This BMS is intended for Victron Lithium NG battery installations and is not the correct match for older Lithium Battery Smart models. It also lacks a VE.Bus interface, so it is not the right control choice for VE.Bus inverter/chargers such as MultiPlus and Quattro units.

For a boat with a Victron Lithium NG house bank, this unit covers the core protection needs without adding unnecessary system complexity. It is especially relevant for smaller cruising, fishing, and auxiliary DC systems where chargers, DC-DC converters, inverters, or BatteryProtect devices can be controlled through remote on/off connections.

Installation and setup

Mount the unit on a flat surface in a dry electrical area and keep wiring runs as short and orderly as practical. The removable 7-pin terminal block helps with wiring in tight panels, and the remote on/off connection must be completed with the supplied loop or a suitable external switch arrangement for correct operation.

After wiring, use VictronConnect to check the detected battery configuration and adjust the available BMS settings. Since this device manages critical charge and load control for a lithium bank, installation should follow the electrical design of the vessel and the connection requirements of the batteries, chargers, and controlled loads.

Electrical and system integration

The load disconnect output has a maximum source current of 1 A, while the charge disconnect output is rated up to 500 mA. The pre-alarm output is rated up to 500 mA and can be used with a relay, LED, or buzzer to warn crew before the system removes loads because of low cell voltage.

Typical marine integration includes linking the charge disconnect output to compatible solar chargers, DC charging equipment, or charge relays, and using the load disconnect output with compatible inverters, DC-DC converters, or BatteryProtect devices. The result is a cleaner lithium installation where the BMS can protect the battery bank without requiring manual intervention during fault conditions.

What’s included

• smallBMS NG with removable 7-pin terminal block