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LG Energy Solution•RESU 10H

Analysis by Marcus & Team

LG RESU 10H: Battery Discharging Overnight When Empty

Troubleshoot LG RESU 10H battery discharging at night. Identify phantom loads, BMS issues, and inverter problems. Expert diagnostic steps and safety tips.

Frequently Asked Questions

•What is the typical standby power consumption of the LG RESU 10H inverter?

The standby power consumption of the LG RESU 10H inverter is typically around 20-50W, but this can vary depending on the specific model and configuration.

•How often should I calibrate the SOC of my LG RESU 10H battery?

LG recommends calibrating the SOC of the RESU 10H battery every 6-12 months, or as needed based on performance.

•What is the warranty period for the LG RESU 10H battery?

The LG RESU 10H battery typically has a 10-year warranty or a specified throughput (e.g., 70% of initial capacity), whichever comes first. Refer to the warranty documentation for specific terms and conditions.

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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:

Working with battery storage systems involves hazardous DC voltages. Always disconnect the DC power supply to the inverter and battery before performing any inspection or maintenance. Follow NEC Article 690 guidelines for solar photovoltaic (PV) systems and battery energy storage. Only qualified electricians should perform invasive diagnostics or repairs. Wear appropriate PPE, including insulated gloves and eye protection.

Solution:

1

Verify AC load profile: Use a clamp meter to measure AC current draw at the main panel to identify any unexpected loads that may be backfeeding to the battery through the inverter.
2

Check Inverter Standby Power: Using a power meter, measure the AC power consumption of the inverter when it is ostensibly in standby mode. Compare to manufacturer specifications.
3

Inspect DC connections: Ensure all DC connections between the battery and inverter are tight and free from corrosion using a multimeter to measure voltage drop across connections.
4

Monitor cell voltages: Access the BMS data through the inverter's monitoring app or service interface to check individual cell voltages for imbalances. An IR thermometer can help identify hot spots.
5

Perform a full discharge cycle: Fully discharge the battery during daylight hours and monitor the SOC reporting. Check for consistent behavior. Note ambient temperature during test.
6

Check for firmware updates: Ensure both the battery and inverter have the latest firmware installed from the manufacturer's website and follow the prescribed update procedure.
7

Contact LG Energy Solution support: If the issue persists, contact LG Energy Solution's technical support for further diagnostics and potential warranty service.

Possible Causes:

Inverter parasitic loads: The inverter continues to draw a small amount of power even when not actively providing AC output.
BMS malfunction: Inaccurate SOC reporting or excessive internal BMS power consumption.
Cell imbalance: Voltage differences between battery cells causing premature termination of discharge cycle.
Communication issues: Inverter misinterpreting SOC data from the BMS or failing to properly shut down DC charging.
Backfeed from AC loads: Small but persistent AC loads drawing power from the battery through the inverter.
DC leakage current: Faulty wiring or components causing DC current to leak from the battery to ground.

Symptoms:

The LG RESU 10H battery system discharges overnight even when reported as empty (0% SOC) during daytime operation in a residential setting.

Technical Overview:

The LG RESU 10H is a lithium-ion battery energy storage system (ESS). It interfaces with a hybrid inverter to store DC power from solar panels or the grid and provide AC power to the home. The Battery Management System (BMS) monitors cell voltages, current, and temperature to protect the battery. Parasitic loads within the BMS and inverter, or inaccurate SOC readings, can cause apparent overnight discharge. Standby power consumption of the inverter and DC-DC conversion losses contribute to the observed drain. The system relies on proper communication between the inverter and the battery.

Expert Tip:

Many inverters have a service menu that allows you to directly view the battery cell voltages and SOC readings. Consult the inverter's system manual for instructions on accessing this menu. Compare the cell voltage readings with manufacturer specifications. This may expose cell imbalance.

Prevention:

Schedule regular firmware updates for both the inverter and battery system as recommended by the manufacturers.
Perform periodic capacity tests (every 6-12 months) to monitor battery degradation and ensure accurate SOC reporting.
Monitor battery temperature, especially during peak charging and discharging periods, to identify potential thermal management issues.
Periodically check the DC disconnect and other electrical connections for tightness and corrosion.