storagefaults.comstoragefaults.com

FranklinWH•aPower

Analysis by Marcus & Team

FranklinWH aPower High Battery Internal Resistance

Troubleshoot high internal resistance in your FranklinWH aPower battery system. Diagnose and resolve this issue for optimal performance and safety.

Frequently Asked Questions

•What are the typical causes of high internal resistance in LFP batteries?

Cell aging, cycling, temperature extremes, and sulfation/lithium plating can all contribute to increased internal resistance.

•How does temperature affect the internal resistance of the battery?

High temperatures accelerate degradation and increase internal resistance, while low temperatures reduce ion mobility and also increase resistance.

•What is the expected lifespan of a FranklinWH aPower battery system?

The expected lifespan depends on usage patterns and environmental conditions, but is typically 10-15 years or a certain number of charge/discharge cycles, as specified in the warranty.

Related questions

Loading related questions...

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.

← Back to list

Pro Tip:

Some BMS systems have a hidden service menu or diagnostic command that can be used to force a cell balancing cycle or reset the internal resistance measurement. Consult the FranklinWH service manual or contact technical support for information on accessing these features. Before replacement, check the CAN bus communication between the BMS and inverter; communication errors can lead to misreported resistance values.

Important Warnings:

Battery storage systems operate at high DC voltage, which poses a significant electrical shock hazard. Disconnecting the system requires adherence to NEC Article 690 and the manufacturer's instructions. Never attempt to work on live circuits. Arc flash hazards are present during DC disconnection. This diagnostic procedure should only be performed by qualified electricians with proper PPE.

Observed Symptoms:

FranklinWH aPower system reports a "High Internal Battery Resistance" error in the monitoring app. Reduced energy storage capacity, faster discharge rates, increased battery temperature during operation, and potential system shutdown due to voltage sag under load.

Step-by-Step Fix:

1

*Safety First:** Disconnect the AC power to the FranklinWH aPower system using the main breaker. Then, disconnect the DC power using the designated DC disconnect switch, adhering to NEC 690.
2

Verify absence of voltage with a calibrated multimeter.
3

*Visual inspection:** Carefully inspect the battery module and its connections for any signs of corrosion, damage, or loose wiring. Pay attention to the busbars and terminal connections.
4

*Resistance Measurement:** Using a four-point probe or impedance meter (if available and appropriate for the system voltage), measure the internal resistance of individual battery cells or modules. Compare readings to manufacturer specifications or baseline data. *Note: This step requires specialized equipment and should only be performed by qualified personnel.*
5

*Temperature Monitoring:** Use an infrared (IR) thermometer to check for hot spots on the battery module. Elevated temperatures can indicate internal shorts or high resistance connections.
6

*BMS Diagnostics:** Access the FranklinWH aPower BMS diagnostics interface (if available to certified technicians) to check for error logs, cell voltage imbalances, and resistance readings. Consult the manufacturer's service manual for instructions.
7

*Firmware Update:** Check for and install any available firmware updates for the BMS. Firmware updates can improve battery management and accuracy of resistance readings.
8

*Qualified Technician Required:** If high resistance is confirmed and the above steps do not resolve the issue, contact a FranklinWH-certified technician for further diagnostics and potential battery module replacement.

Technical Overview:

The FranklinWH aPower utilizes lithium iron phosphate (LFP) battery cells managed by a sophisticated Battery Management System (BMS). The BMS continuously monitors cell voltage, current, temperature, State of Charge (SOC), and State of Health (SOH). Internal resistance of the battery cells is a key indicator of battery health. High internal resistance leads to increased heat generation (I²R losses), reduced voltage under load, and accelerated capacity degradation. The BMS communicates with the inverter to regulate charge/discharge rates and protect the battery from over-voltage, under-voltage, over-current, and over-temperature conditions. DC power flows from the battery to the inverter, which converts it to AC power for household use or grid export. Grid synchronization is essential for seamless operation and backup power during outages. Safety systems include DC disconnects, overcurrent protection, and thermal management.

Possible Causes:

Cell degradation due to aging and cycling.
Sulfation or lithium plating within the cells.
Poor connections within the battery module (e.g., loose busbars, corroded terminals).
Temperature extremes (high or low) accelerating degradation.
BMS malfunction providing inaccurate resistance readings.
Overcharging or deep discharging outside of manufacturer specifications.

Maintenance Tips:

Follow the manufacturer's recommended operating temperature range.
Avoid deep discharging the battery system.
Ensure proper ventilation around the battery module.
Periodically inspect the battery connections for corrosion or looseness.
Keep the BMS firmware up-to-date.