Victron LG Chem RESU CAN-bus ESS Setup: Troubleshooting Communication and Configuration

Key Takeaways

• CAN-bus communication is essential for Victron GX devices to manage LG Chem RESU batteries.
• Always use the specified VE.Can to CAN-bus BMS type B Cable, part number ASS030720018.
• Correctly set the protocol switches on the LG Chem RESU battery and the CAN-profile on the GX device.
• LG Chem RESU batteries are designed for on-grid ESS systems and are not compatible with off-grid setups.

Why is my Victron GX device not communicating with the LG Chem RESU battery?

The most common reason for a Victron GX device failing to communicate with an LG Chem RESU battery is an incorrect CAN-bus setup. The first step is to verify all physical connections and settings are precisely as specified. Without proper CAN-bus communication, the LG Chem RESU will open its internal circuit breaker after 10 minutes.

Diagnosing LG Chem RESU CAN-bus Communication Issues

Follow these steps to diagnose and resolve communication problems between your Victron GX device and LG Chem RESU battery.

1. Check CAN-bus Cable Type and Connection:

• • Observable Check: Inspect the cable connecting the LG Chem RESU BMS to the Victron GX device.
  • What it Means: You must use the VE.Can to CAN-bus BMS type B Cable, part number ASS030720018. Ensure the side labeled "Battery BMS" is plugged into the LG Chem RESU BMS and the side labeled "Victron VE.Can" is plugged into the GX device. Incorrect cabling or connections will prevent communication.

2. Verify VE.Can Terminators:

• • Observable Check: Look at the VE.Can ports on your GX device.
  • What it Means: A VE.Can terminator must be plugged into the unused VE.Can socket on the GX device. Two terminators are typically included with the CCGX, but only one is used for this setup. Missing terminators can disrupt the CAN-bus signal.

3. Confirm LG Chem RESU Protocol Switches:

• • Observable Check: Locate the SW select switches on the LG Chem RESU battery.
  • What it Means: Set SW select switches 3 & 4 on the battery to select the "LGC Smart" protocol. Incorrect switch settings will prevent the battery from communicating with the Victron system.

4. Check GX Device CAN-profile Setting:

• • Observable Check: Navigate through the menu on your Victron GX device: Settings -> Services -> CAN-profile.
  • What it Means: Select the "CAN-bus BMS (500 kbits/s)" CAN-profile. This configures the GX device to communicate with the battery. Note that this setting changes the function of a VE.Can port, meaning you cannot connect both VE.Can products and an LG battery simultaneously to the same port.

5. Confirm ESS Assistant Usage:

• • Observable Check: Verify your Victron inverter/charger configuration.
  • What it Means: LG Chem RESU batteries can only be used in a Victron ESS installation that uses the ESS Assistant. They are designed for on-grid systems for self-consumption, not for off-grid systems. Attempting to use them in an off-grid setup will lead to system malfunction.

6. Note MPPT Compatibility:

• • Observable Check: Identify the type of MPPT Solar Chargers in your system.
  • What it Means: LG Chem RESU batteries may only be used with MPPT Solar Chargers that have a VE.Direct port. VE.Can MPPTs are not supported for use with these batteries.

Common Setup Errors and Fixes for Victron LG Chem RESU

Understanding LG Chem RESU Charge Behavior

When operating an LG Chem RESU battery with a Victron ESS system, it is important to note a specific charging characteristic. LG battery policy is to only charge the battery to 97% or 98%. It is normal for the battery not to charge to 100%. This is a deliberate design choice to optimize the battery's lifespan and performance. Do not attempt to force the battery to 100% charge, as this goes against manufacturer recommendations.

Safety: High Voltage and Current Systems

Working with high-voltage battery systems and power electronics carries inherent risks. Always prioritize safety.

• Isolate Power: Before making any physical connections or disconnections, ensure all power sources (PV, battery, AC grid) are isolated. Turn off all breakers and switches.
• Insulated Tools: Use only insulated tools when working on electrical connections to prevent accidental short circuits. A spanner across battery terminals can short hundreds of amps, causing severe arcing and burns.
• BMS Protection: The LG Chem RESU battery includes a Battery Management System (BMS) that monitors and protects the battery from overcharge, over-discharge, over-current, and temperature extremes. While the BMS provides critical safety functions, it does not negate the need for safe installation practices.
• Professional Installation: If you are unsure about any step, consult a qualified solar technician.

When to call a technician instead

While many communication and setup issues can be resolved with careful diagnosis, there are situations where professional assistance is necessary.

• Persistent Communication Failure: If, after following all troubleshooting steps, your Victron GX device still fails to communicate reliably with the LG Chem RESU battery, a deeper issue may be present.
• Internal Battery Faults: If the battery displays internal fault codes not related to communication, or if its internal circuit breaker trips repeatedly without an obvious external cause, it may indicate an internal battery issue requiring specialized service.
• System Malfunction: For any system behavior that seems abnormal or unsafe, beyond simple communication errors, contact a qualified technician.
• Warranty Concerns: Attempting unauthorized repairs or modifications can void your battery's warranty. If you suspect a hardware fault, contact your installer or the manufacturer's support.
• Off-grid Applications: If you mistakenly purchased an LG Chem RESU for an off-grid system, it will not function correctly. These batteries are strictly for on-grid ESS applications, and a technician can advise on suitable alternatives.