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LG Energy Solution•RESU 13

Analysis by Marcus & Team

LG RESU 13 BMS Error 2 Troubleshooting

Troubleshooting LG RESU 13 Error 2. Diagnose and fix battery management system faults. Safety advice for residential solar+storage systems. Expert tips.

Frequently Asked Questions

•What does BMS Error 2 on an LG RESU 13 battery mean?

BMS Error 2 typically indicates a cell voltage imbalance or a communication fault between the BMS and the inverter in your LG RESU 13 battery system.

•Can I fix the LG RESU 13 Error 2 myself?

Some basic checks, like inspecting wiring and updating firmware, can be performed by the homeowner. However, troubleshooting cell voltage imbalances or communication faults requires specialized knowledge and equipment. Contact a qualified electrician for assistance.

•How often should I service my LG RESU 13 battery?

Schedule regular visual inspections of the battery system and wiring quarterly. Perform periodic capacity tests (e.g., every 2-3 years) to assess battery degradation. Apply manufacturer-recommended firmware updates promptly.

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Marcus leads the technical research department at Storage Faults. Together with a team of systems analysts, he specializes in translating complex solar storage error codes into actionable diagnostic steps for the US market.

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Important Warnings:

Battery systems operate at high DC voltages, posing a significant electrical shock hazard. Always disconnect both AC and DC power before performing any work. Verify zero voltage with a calibrated multimeter. Wear appropriate PPE, including insulated gloves and eye protection. Refer to NEC Article 690 for solar photovoltaic (PV) systems and energy storage systems. NEC 706 covers energy storage systems. A qualified electrician familiar with LG RESU 13 systems must perform all repairs.

Why This Happens:

Individual cell voltage drifting outside the acceptable range.
Faulty NTC temperature sensor reporting inaccurate cell temperatures.
Communication failure between the BMS and the inverter (CAN bus or Modbus).
Degraded battery cell capacity due to aging or excessive cycling.
Loose or corroded wiring connections within the battery module.
Firmware incompatibility between the battery and the inverter.

Technical Background:

The LG RESU 13 integrates lithium-ion battery cells managed by a Battery Management System (BMS). The BMS monitors cell voltages, temperatures (using NTC thermistors), current, State of Charge (SOC), and State of Health (SOH). 'Error 2' typically indicates a cell voltage imbalance or a communication fault between the BMS and the inverter. DC power from the battery is converted to AC power by the inverter for household use or grid export. Proper grounding and overcurrent protection are essential for safety and NEC compliance. The BMS also controls contactors to disconnect the battery in case of critical faults.

Expert Tip:

Some LG RESU models have a hidden diagnostic menu accessible via a specific key sequence on the front panel. Consult the LG RESU system manual or contact LG technical support for the procedure to access detailed battery health information and error logs. This can help pinpoint the source of the 'Error 2' fault faster.

Solution:

1

Disconnect the AC power to the inverter and then the DC disconnect switch for the LG RESU 13 battery. Verify zero voltage using a calibrated multimeter.
2

Inspect all wiring connections to the LG RESU 13, ensuring they are clean, tight, and free from corrosion. Pay close attention to the BMS communication cables (CAN or Modbus).
3

Using the LG ESS Mobile App (installer version) or a compatible diagnostic tool, check individual cell voltages and temperature readings. Document any cells significantly outside the normal range.
4

Check the BMS firmware version and update to the latest version recommended by LG Energy Solution. Ensure inverter firmware is also up to date.
5

If cell voltage imbalance persists, a qualified technician may need to perform a capacity test and cell balancing procedure (if supported by the BMS). This requires specialized equipment.
6

If communication errors persist, verify the CAN bus termination resistance (typically 120 ohms). Use an oscilloscope to check the signal integrity of the CAN bus.
7

After completing the repairs, re-energize the system by first closing the DC disconnect and then the AC breaker. Monitor system performance for 24 hours.

Prevention:

, quarterly) visual inspections of the battery system and wiring
Monitor battery SOC and SOH using the monitoring app
Check for any unusual temperature variations
Keep the battery module clean and free from debris
Apply manufacturer-recommended firmware updates promptly
Perform periodic capacity tests (e