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Panasonic•EverVolt

Analysis by Marcus & Team

Panasonic EverVolt Rapid Battery Discharge Diagnostic

Troubleshoot rapid battery discharge in Panasonic EverVolt systems. Identify causes and solutions for residential energy storage issues.

Frequently Asked Questions

•What is the measured DC bus voltage during charging?

Record the DC bus voltage during charging to diagnose possible overvoltage or undervoltage issues.

•Are there any error codes reported by the BMS?

Document error codes reported by the BMS, as they provide critical insights into the root cause.

•What is the ambient temperature surrounding the EverVolt system?

Battery performance is sensitive to temperature, document for diagnostic purposes.

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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 Panasonic EverVolt system is a DC-coupled battery storage system. It includes lithium-ion or LFP battery modules, a Battery Management System (BMS), a DC-DC converter, and a bidirectional inverter. The BMS monitors cell voltages, temperatures, and currents to manage charge/discharge cycles and protect the battery. The inverter converts DC power from the battery into AC power for household use or grid export. A faster-than-expected discharge can be caused by inefficiencies in the power conversion, incorrect SOC readings, or excessive parasitic loads.

Critical Safety Precautions:

Working with battery storage systems involves high DC voltages which can cause electric shock and arc flash hazards. Always disconnect the system from all power sources before performing any maintenance or repairs. Wear appropriate personal protective equipment (PPE), including insulated gloves and safety glasses. Only qualified electricians should perform work on the system following NEC 706 and manufacturer's safety guidelines. Improper handling of lithium-ion batteries can lead to thermal runaway and fire.

Solution:

1

Disconnect the EverVolt system from the AC grid and DC sources using the appropriate disconnect switches following NEC 690.15 and manufacturer's instructions.
2

Use a calibrated multimeter to measure the DC bus voltage at the battery terminals to ensure it is within the expected range. Record the voltage.
3

Use a DC clamp meter to measure the current draw of the EverVolt system with no load applied to identify any parasitic loads. Compare the reading to the manufacturer's specifications.
4

Access the EverVolt monitoring app or web interface to check the SOC, SOH, and cell voltages. Note any significant cell voltage imbalances.
5

Perform a battery capacity test according to the manufacturer's instructions to verify the actual usable capacity. Note ambient temperature during testing.
6

Check the event logs in the monitoring app for any error codes related to battery performance or BMS operation. Contact Panasonic technical support for assistance interpreting error codes.
7

If a battery module is suspected of being defective, consult a qualified electrician experienced in battery replacement and disposal following all safety guidelines and local regulations. Replacement must be performed by qualified installer.

Observed Symptoms:

The Panasonic EverVolt battery storage system discharges at a rate significantly faster than the connected home load would indicate. Observed SOC drops more rapidly than expected based on the energy consumption of connected appliances and devices. Backup power duration is shorter than estimated.

Technical Recommendation:

Many inverters include a hidden diagnostic menu accessible by pressing a specific sequence of buttons. This menu can provide detailed information about battery health, cell voltages, and system performance. Consult the manufacturer's service manual for the key combination. Check DC bus ripple voltage with an oscilloscope to identify inverter issues.

Common Causes:

Defective battery module with reduced capacity or increased internal resistance.
BMS calibration error resulting in inaccurate SOC reporting.
Parasitic loads within the EverVolt system (e.g., cooling fans, control circuits) drawing excessive current.
Inefficient DC-DC converter or inverter operation leading to power losses.
Incorrect configuration settings for charge/discharge parameters.
High self-discharge rate due to battery degradation or internal shorts.

Preventative Care:

Schedule regular firmware updates for the EverVolt system to ensure optimal performance and accurate SOC reporting
Periodically perform a full charge/discharge cycle to calibrate the BMS
Monitor the system's temperature and ventilation to prevent overheating
Keep the battery enclosure clean and free of debris
Check the battery string voltage every 6 months to verify the balance between battery modules