Victron smallBMS NG wiring diagram

The smallBMS NG is for Victron Lithium NG batteries. It is incompatible with the earlier Lithium Battery Smart family. It has Bluetooth configuration and battery monitoring but no VE.Bus interface. The manual, printed pages 2–3, specifically excludes direct use as the BMS for VE.Bus MultiPlus/Quattro inverter/chargers.

This is a control device, not a pack-current switch. A 1 A output rating describes a control circuit, not the battery bank's allowable current.

The catalog + and − correspond to Bat+ and Bat− on the seven-pin connector. They power the electronics. Printed page 21 specifies a 0.3–2.5 A supply fuse, selected for the devices powered by the outputs; this is not a battery-main-fuse recommendation. Ensure the actual supply lead, terminals and connected loads all support the chosen protection.

Daisy-chain the NG battery communication cables and connect their ends to the BMS. The remote L/H terminals require the supplied loop, a switch between them, or the documented high/low control arrangement. The two-terminal catalog drawing omits all of these mandatory control connections.

Load disconnect normally sources approximately battery voltage, up to 1 A; Charge disconnect sources up to 500 mA. Each becomes free-floating when permission is withdrawn. They are not dry contacts and are not short-circuit protected. Check the receiving equipment's remote-input polarity; some products need an inverting or non-inverting interface cable.

Charge disconnect must not power an inductive relay coil. Use the approved remote-control interface or compatible switching equipment. Every charge source and every load must obey its corresponding BMS permission, including equipment omitted from the drawing.

The manual conflicts on the pre-alarm output: feature prose says 1 A, while its specification table says 500 mA. Use the table's lower limit unless Victron confirms otherwise for the supplied unit.

Use VictronConnect to verify automatically detected bank voltage, capacity and battery count, then configure the discharge floor and warning level. Set charger and load current limits for the actual batteries; the BMS control outputs do not regulate arbitrary external equipment by themselves.

Test permission-driven shutdown, remote off and warning indication. Low-cell shutdown leaves little reserve, so recharge promptly and account for residual currents during storage. The drawing omits the separate power switchgear, battery communication chain, interface cables and fault-protection selection required for a complete installation.