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LG Energy Solution•RESU 13

Analysis by Marcus & Team

LG RESU 13 DC Link Overvoltage Troubleshooting

Troubleshoot DC link overvoltage on an LG RESU 13 battery. Learn causes, diagnostics, safety tips, and solutions for your residential energy storage system.

Frequently Asked Questions

•What is the typical DC link voltage for an LG RESU 13?

The typical DC link voltage for an LG RESU 13 is between 350V and 450V, but it varies depending on the system's state of charge and operating conditions. Refer to the manufacturer's specifications for precise values.

•How does regenerative braking contribute to DC link overvoltage?

During regenerative braking, the inverter converts excess energy from the grid back into DC power to charge the battery. If the battery is fully charged or the inverter's charging capacity is exceeded, the DC link voltage can rise rapidly, leading to an overvoltage fault.

•What NEC articles are relevant to residential battery storage systems?

Relevant NEC articles include 690 (Solar Photovoltaic (PV) Systems), 705 (Interconnected Electric Power Production Sources), 706 (Energy Storage Systems), and applicable sections of Article 110 (Requirements for Electrical Installations).

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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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Technical Background:

The DC link in the LG RESU 13 is the high-voltage DC bus that connects the battery to the inverter's DC-DC converter and DC-AC inverter stage. Overvoltage occurs when the DC link voltage exceeds the inverter's maximum allowable input voltage. This can be caused by regenerative braking from the grid, voltage spikes during charging, or malfunction of the inverter's voltage regulation circuitry. The BMS monitors the DC link voltage and triggers a fault to protect the system. Rapid shutdown is initiated when the DC link voltage exceeds the safety threshold.

Symptoms:

The LG RESU 13 displays a 'DC Link Overvoltage' error, potentially causing system shutdown or preventing normal operation. The inverter may disconnect from the grid. Battery charging or discharging is interrupted.

Important Warnings:

High DC voltage is present in the LG RESU 13 and inverter. Improper handling can result in serious injury or death. Always disconnect the system from the grid before performing any maintenance or troubleshooting. Only qualified electricians should work on the high-voltage components. Adhere to NEC 690 requirements for PV systems. Arc flash hazard exists during live circuit testing.

Common Causes:

Inverter malfunction causing excessive DC link voltage.
Regenerative braking from the grid during power export exceeding inverter handling capacity.
Faulty voltage sensor in the DC link circuit.
DC capacitor failure within the inverter stage leading to voltage instability.
Incorrect grid voltage settings configured in the inverter.
Transient voltage surges from the grid affecting the DC link voltage.

Solution:

1

Disconnect the LG RESU 13 from the grid by opening the AC disconnect and the DC disconnect (NEC 690.13). Verify zero voltage using a calibrated multimeter.
2

Inspect the inverter for any visible damage, loose connections, or signs of overheating.
3

Check the inverter's event log for any related fault codes or warnings preceding the DC link overvoltage.
4

Using a multimeter, measure the DC link voltage with the system disconnected to check for any residual voltage or leakage. Ensure compliance with NEC 690.12 rapid shutdown requirements.
5

Verify the grid voltage settings in the inverter configuration menu. Ensure they match the local grid voltage (e.g., 240V).
6

Test the inverter's response to simulated grid power export. Monitor the DC link voltage for any instability using a clamp meter to monitor current flow.
7

If the issue persists, contact a qualified LG Energy Solution technician for inverter repair or replacement.

Maintenance Tips:

Regularly update the inverter and BMS firmware to the latest versions.
Periodically inspect the battery and inverter connections for tightness and corrosion.
Monitor the system's performance and voltage levels through the monitoring app.
Ensure proper ventilation around the inverter to prevent overheating.
Perform periodic capacity testing to verify battery health.