The smallBMS NG with pre-alarm is an all-in-one Battery Management System (BMS) for Victron Lithium NG batteries (not to be confused with the lithium smart batteries without NG). These batteries are Lithium Iron Phosphate (LiFePO4 ) batteries and are available in 12.8V, 25.6V and 51.2V in various capacities.

They can be connected in series, parallel, or a combination of both to create battery banks for system voltages of 12V, 24V, or 48V. A maximum of 50 batteries can be used when configuring a bank with 12V or 24V batteries, while up to 25 batteries can be used with 48V batteries. This allows for a maximum energy storage capacity of 192 kWh with 12V batteries, up to 384 kWh with 24V batteries, and 128 kWh with 48V batteries. For comprehensive details about these batteries, visit the Victron Lithium NG battery product page.

The smallBMS NG is a simple and cost-effective alternative to the VE.Bus BMS NG, but lacks a VE.Bus interface and is therefore not suitable for use with VE.Bus MultiPlus and Quattro inverter/chargers.

Features

• Bluetooth Smart: The smallBMS NG includes Bluetooth Smart for wireless configuration, monitoring, and firmware updates via the VictronConnect App. Instant Readout shows key data such as SoC, battery temperature, warnings, and alarms directly in the device list, without needing to connect.
• Load disconnect output: Controls the remote on/off input of a BatteryProtect, Inverters, DC-DC converter, or other loads with remote on/off functionality. Due to its maximum output current of 1A, it can even control a high-current relay or a contactor. Note that a non-inverting or inverting on/off cable may be required, please consult the manual.
• Charge disconnect output: Controls the remote on/off port of chargers such as the Smart Charger IP43, a Cyrix-Li-Charge relay, a Cyrix-Li-ct Battery Combiner or a BatteryProtect. Note that the Charge disconnect output is not suitable to power an inductive load such as a relay coil.
• Pre-alarm output: Triggers a visible or audible warning when battery voltage is low, activating at least 30 seconds before the Load Disconnect output is disabled due to cell undervoltage. Can drive a relay, LED, or buzzer. Maximum output current: 1A (not short-circuit protected).
• Remote on/off terminal: Allows remote control of the Load and Charge Disconnect outputs. When off, both outputs become free-floating, turning off connected loads and chargers.
• LED indicators: The smallBMS NG has two LEDs: a blue LED for Bluetooth status and a red LED for warnings and alarm errors.
• Configurable discharge floor: Sets the minimum SoC to prevent excessive discharge while ensuring enough energy for self-discharge. A low SoC warning is triggered in VictronConnect, activating the pre-alarm output when the discharge floor is near. A low SoC alarm is triggered when the discharge floor is reached, and the BMS immediately deactivates the ATD output, effectively shutting off any loads it controls

When fully

1. To reduce required balancing time, we recommend using a little different batteries in series as possible for the application. 24V systems are best built using 24V batteries. And 48V systems are best built using two 24V batteries in series. While the alternative, four 12V batteries in series, will work, it will require more periodic balancing time.

Cyrix Combiners designed for use with the smallBMS and the VE.Bus BMS:

• Cyrix-Li-ct (120A or 230A) Is a battery combiner with a Li-ion adapted engage/disengage profile and a control terminal to connect to the Charge Disconnect of the BMS.
• Cyrix-Li-Charge (120A or 230A) Is a unidirectional combiner to insert in between a battery charger and the LFP battery. It will engage only when charge voltage from a battery charger is present on its charge-side terminal. A control terminal connects to the Charge Disconnect of the BMS.