The Victron Lynx Smart BMS is the premium battery management system for Victron lithium batteries. It replaces the older VE.Bus BMS and provides tighter integration with the Lynx power distribution ecosystem and GX monitoring devices. This guide walks you through the complete wiring, configuration, and commissioning process for the Lynx Smart BMS in a Victron lithium system.
What the Lynx Smart BMS Does
The Lynx Smart BMS sits between your Victron lithium batteries and the rest of your electrical system. Its core functions are:
- Cell monitoring: Reads individual cell voltages and temperatures from compatible Victron lithium batteries (Smart and NG ranges)
- Contactor control: Contains a high-current contactor that physically disconnects the battery from the system if a critical fault is detected (over-voltage, under-voltage, over-temperature, over-current)
- Charge/discharge limits: Communicates real-time maximum charge voltage, charge current, and discharge current to the Cerbo GX via CAN-bus, which then distributes these limits to all connected chargers and inverters via DVCC
- Pre-alarm warnings: Sends warnings to the GX device before hard cutoffs, allowing the system to reduce loads gracefully
- Cell balancing coordination: Works with the batteries' internal BMS to ensure cells remain balanced across the bank
System Components Overview
A complete Lynx-based system typically includes these components, connected in a modular chain:
- Victron lithium batteries (Smart or NG range)
- Lynx Smart BMS — connects directly to the batteries via both power cables and a data cable
- Lynx Distributor — power distribution with integrated Mega fuse holders for each circuit
- Lynx Shunt (optional but recommended) — precision current measurement for accurate state of charge
- Cerbo GX — system brain, connects to the Lynx Smart BMS via CAN-bus
The Lynx modules are designed to physically snap together using bus bar connections, creating a clean, professional installation with minimal cable runs between components.
Wiring the Lynx Smart BMS
Battery to Lynx Smart BMS Connection
The Lynx Smart BMS connects to your battery bank using standard battery cables. The positive and negative terminals on the battery side of the BMS connect directly to your battery bank's positive and negative terminals. Size your cables for the maximum expected current — the Lynx Smart BMS supports up to 500A continuous.
Critical points:
- Keep battery cables as short as possible to minimise voltage drop
- Use equal-length cables if running parallel batteries to the BMS
- The battery-side fuse should be within 30cm of the battery positive terminal
- Torque all bolt connections to the specified value (typically 10–14 Nm for M8 terminals)
BMS Data Cable
In addition to the power cables, the Lynx Smart BMS connects to the batteries via a dedicated data cable (BMS cable). This is how it reads individual cell voltages and temperatures. The cable connects from the BMS to the first battery, and if you have multiple batteries, they daisy-chain from one to the next. This cable is included with the Lynx Smart BMS and additional cables are available for multi-battery setups.
Lynx Smart BMS to Lynx Distributor
The system-side output of the Lynx Smart BMS connects to the Lynx Distributor. If the modules are physically snapped together, the internal bus bars make this connection automatically — no separate cables needed. If they are mounted separately (not recommended but sometimes necessary), use appropriately sized bus bar links or cables.
Lynx Distributor to Loads and Chargers
The Lynx Distributor provides four fused connection points. Typical allocation:
- Position 1: MultiPlus or Quattro inverter/charger
- Position 2: MPPT solar charge controller(s)
- Position 3: DC distribution (lights, pumps, USB chargers via a secondary fuse box)
- Position 4: Spare or additional device (Orion DC-DC charger, windlass, etc.)
Each position accepts a Mega fuse. Size the fuse for the device connected to it — not the maximum the slot can hold.
CAN-bus Connection to Cerbo GX
The Lynx Smart BMS communicates with the Cerbo GX via a CAN-bus connection. Use a standard RJ45 Ethernet cable (not a crossover cable) between the VE.Can port on the Lynx Smart BMS and one of the VE.Can ports on the Cerbo GX.
Important CAN-bus rules:
- The CAN-bus must be terminated at both ends. The Lynx Smart BMS has a built-in terminator. The Cerbo GX's VE.Can port also needs a terminator — use the included VE.Can terminator plug in the second VE.Can port if nothing else is connected
- If you have other CAN-bus devices (e.g., Lynx Shunt, Orion XS), they daisy-chain on the same CAN-bus. Only the two end devices should have terminators active
- Do not use CAN-bus cable runs longer than 50 metres
- Use shielded Ethernet cables in electrically noisy environments (near inverters, motors)
Configuring DVCC
Once the Lynx Smart BMS is connected to the Cerbo GX via CAN-bus, DVCC (Distributed Voltage and Current Control) should be enabled on the Cerbo. Navigate to Settings > DVCC in the Cerbo GX menu.
- DVCC: Enable
- SVS (Shared Voltage Sense): Enable — uses the BMS voltage measurement as the reference for all devices
- STS (Shared Temperature Sense): Enable — uses the BMS temperature as the reference
- SCS (Shared Current Sense): Enable if using Lynx Shunt
With DVCC active, the Cerbo GX automatically sends charge voltage limits, charge current limits, and discharge current limits from the BMS to all connected MPPT controllers and MultiPlus/Quattro inverter-chargers. You do not need to set individual charge parameters on each device — the BMS controls everything via the GX.
Pre-Alarm and Alarm Thresholds
The Lynx Smart BMS uses a two-stage protection system:
Pre-Alarm (Warning)
The BMS sends a warning to the GX device and begins reducing charge or discharge current limits. This gives the system time to react gracefully. Pre-alarm conditions include:
- Cell voltage approaching high or low limits
- Battery temperature approaching limits
- Current approaching maximum rated values
Alarm (Disconnect)
If conditions continue to worsen past the pre-alarm thresholds, the BMS opens its contactor, physically disconnecting the battery from the system. This is a hard disconnect — all loads lose power instantly. The contactor reconnects automatically once conditions return to safe levels, but this should be treated as a fault condition to investigate, not normal operation.
Contactor Operation
The internal contactor in the Lynx Smart BMS is a critical safety component. It is normally open (disconnected) when the system is off, and closes (connects) when the system is powered up and conditions are safe.
- Normal startup: The contactor closes after the BMS verifies all cell voltages and temperatures are within limits
- Fault disconnect: The contactor opens within milliseconds of an alarm condition
- Manual disconnect: The BMS can be commanded to open the contactor via the GX device for maintenance
- Pre-charge: The Lynx Smart BMS includes a pre-charge circuit to safely charge the capacitors in connected inverters before closing the main contactor, preventing damaging inrush currents
Temperature Monitoring
The Lynx Smart BMS monitors battery temperature via sensors built into the Victron lithium batteries (connected via the data cable). Temperature affects charge and discharge limits:
- Below 5°C: Charging is restricted or disabled entirely to prevent lithium plating on the cells. If using batteries with the heating option, the BMS activates heating first
- 5–45°C: Normal operation, full charge and discharge rates permitted
- Above 45°C: Current limits are progressively reduced. Above 50°C, the contactor may open
This is particularly important for UK installations in unheated spaces — garages, boats, and motorhomes can easily drop below 5°C in winter. See our guide on charging LiFePO4 batteries correctly for more on cold-weather charging.
Common Installation Mistakes
- Forgetting CAN-bus terminators: Without proper termination, CAN-bus communication is unreliable. The Lynx Smart BMS may intermittently lose connection with the Cerbo GX, causing DVCC limits to reset or drop to zero
- Wrong CAN-bus cable: Using a crossover Ethernet cable instead of a straight-through cable. Standard patch cables are correct
- Missing the BMS data cable: Connecting only the power cables and forgetting the data cable means the BMS cannot read cell voltages. It will report a fault and refuse to close the contactor
- Undersized battery cables: The Lynx Smart BMS supports 500A, but if your cables are only rated for 200A, the fuse or cable becomes the weak point
- Not enabling DVCC: The Lynx Smart BMS sends data via CAN-bus, but if DVCC is not enabled on the Cerbo GX, that data is ignored and charge limits are not distributed to the chargers
- Mounting in a damp location: The Lynx modules are not waterproof. Condensation in marine or outdoor installations can cause corrosion on the bus bars
- Skipping the pre-charge: Connecting large inverters directly to a battery bank without pre-charge causes enormous inrush current. The Lynx Smart BMS handles this, but only if it is the connection point between battery and inverter
Firmware Updates
The Lynx Smart BMS receives firmware updates via the Cerbo GX when connected to the internet (VRM). Check for updates after installation and periodically thereafter. Updates can improve fault detection, adjust protection thresholds, and add features. Always update all Lynx modules (BMS, Distributor, Shunt) to compatible firmware versions.
