Victron smallBMS NG: Advanced Battery Management for Victron Smart Lithium Systems

Precision Protection for 12V, 24V, and 48V LiFePO4 Battery Banks

The Victron smallBMS NG (BMS400100000) is a compact, next-generation battery management system engineered to safeguard Victron Smart LiFePO4 batteries in off-grid, marine, and mobile applications. Replacing the earlier miniBMS, this unit delivers reliable cell-level monitoring and control without the complexity or cost of a full VE.Bus BMS. It is purpose-built for systems where a VE.Bus interface is not required, making it an ideal match for standalone inverters, DC-DC converters, and solar charge controllers.

Designed for seamless integration with Victrons M8 circular connector Smart Lithium batteries, the smallBMS NG actively prevents deep discharge, overcharge, and temperature extremes. Its three independent outputsLoad Disconnect, Charge Disconnect, and Pre-Alarmprovide layered protection that extends battery service life and enhances system safety. Whether you are building a 12V caravan solar setup, a 24V marine power system, or a 48V off-grid energy storage solution, this BMS ensures your lithium investment remains protected under all operating conditions.

Three-Stage Protection Architecture

The smallBMS NG continuously monitors individual cell voltages and battery temperature via the Victron batterys internal BMS communication. When parameters approach critical thresholds, it initiates a sequenced response:

• Load Disconnect Output: Normally high (Vbat 0.1V), this output transitions to free floating when any cell drops below the under-voltage threshold (default 2.8V/cell, adjustable 2.62.8V). With a 1A source current limit, it can directly drive a high-current relay, contactor, or the remote on/off input of a Victron BatteryProtect, inverter, or DC-DC converter. This prevents irreversible cell damage from over-discharge.
• Pre-Alarm Output: Provides an early warning signal before load disconnect occurs. Normally free floating, it activates (Vbat 0.1V, 1A max) when cell voltage falls to the pre-alarm threshold (default 3.1V/cell, adjustable 2.853.15V). A minimum 30-second delay before load disconnect gives systems time to shed non-critical loads or start a generator, avoiding unexpected shutdowns.
• Charge Disconnect Output: Normally high (Vbat 0.6V), this output goes free floating to signal an imminent cell over-voltage or over/under-temperature condition. With a 10mA source current limit and short-circuit protection, it is designed to control the remote on/off of chargers, Cyrix-Li-Charge relays, or Cyrix-Li-ct Battery Combiners. This ensures charging stops before cells exceed safe voltage or temperature limits.

Flexible System On/Off Control

The Remote L and H terminals allow straightforward system-wide on/off switching. Three control modes are supported: bridging L and H, pulling L to battery negative (<3.5V), or applying a high signal to H (2.9V to Vbat). This flexibility simplifies integration with external switches, BMS panels, or automated controllers, enabling a single point of control for both loads and chargers.

Built for Harsh Environments

Housed in a matt black ABS enclosure rated IP20, the smallBMS NG measures just 106 x 42 x 23 mm and weighs 0.1 kg. It operates across a wide temperature range of -20 to +50C and tolerates up to 95% non-condensing humidity. The compact footprint allows installation in tight electrical compartments typical of caravans, boats, and equipment cabinets. Status LEDs provide immediate visual feedback: a blue Load ON indicator confirms active load output, while a red Temp or OVP LED warns of charge disconnect due to temperature or over-voltage events.

Why Choose the Victron smallBMS NG?

• Direct compatibility with Victron Smart LiFePO4 batteries featuring M8 circular connectorsno additional interfaces required.
• Wide operating voltage range of 870 VDC supports 12V, 24V, and 48V nominal systems from a single model.
• Ultra-low power consumption: typically 2.2 mA when remote on, minimising parasitic drain on the battery bank.
• Pre-alarm functionality reduces the risk of sudden system shutdowns by providing advance warning of low cell voltage.
• Automotive-grade compliance to UN/ECE-R10 Rev.4, plus safety and EMC standards (EN 60950, EN 61000-6-3, EN 55014-1, EN 61000-6-2, EN 61000-6-1, EN 55014-2), ensuring reliable operation in vehicle and marine environments.

Applications

The smallBMS NG is the preferred battery management solution for Victron lithium systems where a VE.Bus MultiPlus or Quattro inverter/charger is not used. Typical installations include:

• Caravans and camper trailers with standalone inverters and MPPT solar controllers.
• Marine electrical systems using alternator charging via Cyrix-Li-ct relays.
• Remote off-grid cabins and tiny homes with DC-only or non-VE.Bus AC systems.
• Portable power packs and mobile workstation setups.

By offloading critical protection functions to a dedicated BMS, you reduce the risk of cell damage, improve system reliability, and simplify wiring compared to generic or multi-brand solutions. The smallBMS NG is not suitable for use with VE.Bus inverter/chargers; for those applications, consider the VE.Bus BMS.

Protect Your Lithium Investment

Equip your Victron Smart Lithium battery bank with the smallBMS NG and gain confidence that your cells are monitored and protected around the clock. Order the Victron smallBMS NG today and build a safer, longer-lasting energy system for your next adventure or off-grid project.