Victron Energy SmallBMS Battery Management System, For Smart LiFePO4 Batteries with M8, 8-70V DC

Overview

The Victron Energy BMS400100000 is a smallBMS with pre-alarm for Victron Lithium Battery Smart LiFePO4 batteries that use M8 circular connectors. It gives the battery bank the basic control signals needed to protect connected loads and charging equipment, without adding a VE.Bus interface.

This unit works with battery systems built around Victron 12.8 V and 25.6 V Lithium Battery Smart batteries in 12 V, 24 V or 48 V arrangements. Its 8 to 70 VDC operating range suits many DC installations found on cruising boats, workboats and compact off-grid marine systems.

The smallBMS is a good fit when the installation needs battery protection logic for loads, chargers, relays or remote on/off devices, but does not use VE.Bus MultiPlus or Quattro inverter/chargers. With IP20 protection, it belongs in a dry electrical locker, console, battery compartment enclosure or other protected onboard location rather than an exposed cockpit or washdown area.

Key features

• Works with Victron Lithium Battery Smart LiFePO4 batteries fitted with M8 circular connectors.
• Supports 12 V, 24 V and 48 V battery banks, with an 8 to 70 VDC operating voltage range.
• Load disconnect output can control a BatteryProtect, inverter, DC-DC converter, compatible DC load remote input, relay or contactor, with a 1 A source current limit.
• Charge disconnect output can control compatible charger remote inputs, a Cyrix-Li-Charge relay, a Cyrix-Li-ct Battery Combiner or a BatteryProtect.
• Pre-alarm output can trigger a visible or audible warning at least 30 seconds before the load disconnect output is disabled due to cell undervoltage.
• Remote on/off terminals allow the load and charge disconnect outputs to be switched off together for service, storage or manual system control.
• Two LED indicators show load output status and charge disconnect conditions related to cell voltage or battery temperature.
• Compact ABS enclosure measures 106 x 42 x 23 mm and weighs about 0.1 kg, making it easy to place inside a protected DC distribution area.

Electrical and system integration

The load disconnect output is normally high and becomes free floating when the battery reaches the low cell voltage threshold. This is useful for shutting down compatible DC loads before the battery is driven too low, which matters on boats where navigation electronics, lighting, pumps and communication gear may share the same battery bank.

The charge disconnect output is normally high and becomes free floating during conditions such as high or low cell temperature, high cell voltage or imminent low cell voltage. It is intended for control inputs, not for powering an inductive relay coil directly.

The pre-alarm output gives installers a practical way to add an early warning device, such as a buzzer or indicator light, before the system disconnects loads. That warning window can help a skipper react before electronics or other DC equipment shut down.

Installation and mounting

Mount the unit in a dry, protected location close enough to the battery and DC control wiring to keep the installation tidy and serviceable. The IP20 rating means it should be kept away from spray, bilge moisture, deck washdown, salt mist and areas where loose conductive objects may contact terminals.

Use appropriately sized wiring and fusing for the connected control circuits. The recommended fuse size for the power supply cable is 0.3 A to 2.5 A, depending on the devices connected to the load disconnect and pre-alarm outputs.

Compatibility notes

This smallBMS is for Victron Smart LiFePO4 battery systems with M8 circular connectors. It is not suitable for use with VE.Bus MultiPlus and Quattro inverter/chargers because it has no VE.Bus interface.

For marine owners building or refitting a Victron lithium house bank without VE.Bus inverter/charger control, it keeps the installation simpler while still giving the battery bank the load, charge and warning signals needed for safe DC system operation.