Logs Pylontech & Balancing: Expert Diagnosis Warranty 2026

Introduction: Why Pylontech Logs are Essential

When a problem occurs with a Pylontech battery (US2000C, US3000C, US5000 or Force L/H), retrieving the log files is the first mandatory step in any professional diagnosis. These operating logs contain the complete history of voltages, currents, cycles and alarm events, enabling the precise nature of the fault to be identified.

Since October 2025, Pylontech has tightened its requirements for warranty claims: without usable logs and a complete form, your claim may be refused or delayed for several weeks. This guide details the official procedure for recovering logs via Battery View, the DC balancing method recommended by the manufacturer, and the best diagnostic practices that every professional should master.

Part 1: Retrieving Pylontech Logs with Battery View

1.1 Equipment Required

To correctly extract the logs from your Pylontech batteries, you will need :

• Battery View software: official Pylontech application (free, download here on Google Drive)
• Console to USB recovery cable: 2 models depending on your battery (see below)
• Laptop with USB port (Windows/Mac)
• Physical access to the battery: the battery must be accessible and switched on

⚠️ Please note: The recovery cable is NOT just a standard RS232 cable. It is a specific adapter with logic level conversion. Wattuneed offers 2 models depending on your battery series:

- Cable for US2000C / US3000C / US5000:
→ Order the US2000C/US3000C/US5000 cable

- Cable for US2000 / US2000+ / U3000 (older versions):
→ Order US2000/US2000+/U3000 cable

1.2 Log Recovery Steps

Step 1: Install Battery View

1. Download Battery View via this direct link: Battery View on Google Drive
2. Install the software on your computer (Windows/Mac)
3. Install the USB drivers if requested by the system
4. Important note: Battery View is not available on the official Pylontech website, use the Google Drive link above.

Step 2: Physical Connection

1. Locate the Console port on the front panel of the Pylontech battery (RJ45 connector with "Console" label)
2. Connect the appropriate recovery cable for your model to the Console port on the battery
3. Connect the USB end of the cable to your computer
4. Check that Windows recognises the device (a new COM port should appear in the Device Manager)

Step 3: Extracting logs with Battery View

1. Launch the Battery View application
2. Select the correct COM port in the connection settings (usually COM3, COM4 or COM5)
3. Configure the serial settings:
   • Baud rate: 115200 (default) or 9600 depending on DIP switch 1
   • Data bits: 8
   • Stop bits: 1
   • Parity: None
4. Click on "Connect" or "Detect".
5. Once the battery has been detected, navigate to the "Log Export" or "Data Export" section
6. Export the 2 mandatory files :
   • XXXXXXXXXX_history.txt: complete history (Data Items, up to 1800 records)
   • XXXXXXXXXX_event.txt: critical events and alarms
7. Clearly name your files with the full serial number (e.g. HPTCR03261A32603_history.txt).

1.3 Interpreting log files

Log files contain essential diagnostic data:

Analysis example: Unbalanced cell

In the example of logs provided (US2000C series HPTCR03261A32603), we observe :

• Cell #8 (Battery ID 9): voltage at 2922 mV while the others are at ~3330 mV
• Cell #8 voltage status: "Low" (automatic BMS detection)
• Cell #8 SOC: between 1% and 25% depending on charge phase
• Repeated OV events: cell #8 reaches 3651-3661 mV on load (OV threshold = 3650 mV)

Probable diagnosis: Cell #8 has a significant loss of capacity (accelerated ageing or internal fault). Passive balancing by the BMS is no longer sufficient to compensate for the difference. This cell requires either forced DC balancing or replacement if the discrepancy persists after balancing.

Part 2: Official Pylontech DC Balancing Procedure

2.1 What is Balancing and Why is it Necessary?

Balancing is the process of equalizing the voltages of all the cells in a lithium battery. Over the course of cycles, voltage differences are naturally created between cells as a result of :

• Variations in internal resistance
• Differences in self-discharge
• Uneven ageing
• Different operating temperatures

An imbalance of more than 100 mV between cells leads to :

• Reduction in total usable capacity
• Premature tripping of OV/UV protections
• Accelerated ageing of weak cells
• Loss of overall system efficiency

Passive balancing vs. active balancing: Pylontech BMSs use passive balancing (dissipation by resistors) limited to ~0.3A per cell. For large imbalances (>200 mV), DC balancing with an external charger (active method) is required.

2.2 Hardware Requirements for DC Balancing

2.3 Complete Balancing Procedure (Official Pylontech Method)

Step 1: Secure Physical Connections.

For US2000/US3000/US5000 (48V series):

1. Turn off the battery (Power Switch OFF)
2. Connect the power cables to the + and - terminals of the battery.
3. Important: Be sure to observe the correct polarity (red = +, black = -)
4. Connect the other end of the cables to the DC charger (double-check polarity before switching on)
5. Insulate all exposed connections with high voltage insulation tape

For Force L: Make a temporary short circuit on the communication ports (see Pylontech DC Charger SOP documentation page 6) to allow direct charging without an active BMS.

For Force H (H1/H2/H3): The module must be placed on its base, with the specific Force H connector connected. 8 AWG or 10 AWG cables must be used.

Stage 2: Initial charge (Capacity recovery)

This phase is used to bring all the cells to a sufficient level of charge before fine balancing.

Procedure:

1. Set the DC charger to the voltage and current indicated in the table.
2. Switch on the DC charger
3. Monitor the charging current: it should decrease gradually
4. When the current reaches 0 A (or <0.1 A), proceed to the next step
5. Typical duration: 30 minutes to 2 hours depending on the initial state of charge

Stage 3: Holding charge (Stabilisation)

This reduced-current phase allows the BMS to begin passive balancing.

Typical duration: 1 to 3 hours. The current decreases more slowly than in the previous stage.

Stage 4: Balancing Final

This is the critical phase when balancing actually takes place. The very low current (0.3 A) enables the BMS to balance the high cells without overloading the low cells.

Monitoring balancing :

• Use Battery View or a multimeter to check cell voltages every 30 minutes
• The difference between the highest and lowest cell should gradually decrease
• Typical duration: 2 to 8 hours depending on initial imbalance
• Target: maximum difference ≤ 30 mV between all cells

Professional tip: If after 12 hours of balancing at 0.3A the difference remains >50 mV, this indicates a faulty cell requiring replacement. Never exceed 12 consecutive hours without a break.

Step 5: Post-balancing check

1. Switch off the DC charger
2. Disconnect the power cables
3. Allow the battery to rest for at least 30 minutes
4. Switch the battery back on (Power Switch ON + press SW button)
5. Reconnect the log recovery cable
6. Extract the new logs to check :
   • Cell voltage difference ≤ 30 mV
   • Consistent SOC between cells (≤ 5% difference)
   • Absence of OV/UV/BLV/BHV alarms

Part 3: Good Practices and Routine Diagnostics

3.1 Preventive Maintenance of Pylontech Batteries

6 Month Rule: Mandatory Charge

If a Pylontech battery remains stored without use for more than 6 months, it must be recharged to ≥90% SOC to avoid:

• Deep self-discharge (irreversible UV risk)
• Cell sulphation (permanent loss of capacity)
• Progressive unbalancing
• Cancellation of the manufacturer's warranty

Recommended Annual Check

Every year after installation, check :

• Electrical connections: tightness of terminal blocks, absence of oxidation
• Earthing: resistance <0.1 Ω
• Environment: temperature (ideally 10-25°C), humidity, dust, presence of insects
• BMS logs: extraction for trend analysis (SOH degradation, increase in alarm events)

3.2 Common Diagnostics : Symptoms and Solutions

3.3 Advanced Analysis: Understanding Event Codes

Pylontech logs use standardized event codes:

3.4 Case Study: Diagnosing a Failed US2000C Battery

Analysing the logs provided (HPTCR03261A32603), we identify :

• SOH = 98%: Excellent state of health (recent battery)
• Cycles = 287: Low usage (~3% of lifetime)
• Bat OV Times = 11600: High number of overvoltage events!
• Reset Times = 201: Frequent restarts (instability)

Detailed analysis of cell #8 :

ID BVolt BTempr BVolt.St BTemp.St SOC 9 2922 17000 Low Normal 0% ← PROBLEM CELL 9 3601 28500 High Normal 21% ← Abnormal peak on load 9 3650 28700 OV Normal 25% ← OV protection triggered

Diagnostic conclusions:

1. Cell #8 faulty: difference >400 mV with the other cells.
2. High internal resistance: cell voltage rises sharply on charging
3. Reduced capacity: SOC stuck between 0-25% when the pack is at 36-39%.
4. Recurrent OV protection: the BMS stops charging as soon as cell #8 reaches 3.65V

Recommendation: Attempt DC balancing in 3 stages. If after balancing the difference remains >100 mV, replace the battery under warranty (proven material fault, not related to use).

Part 4: Pylontech 2025 Warranty Request Procedure

4.1 Mandatory Form and Required Documents

Since October 2025, Pylontech requires a complete file including :

Technical Form (to be completed)

• Serial number (SN): visible on battery label or log file (e.g. HPTCR03261A32603)
• Mix old/new batteries: Yes / No
• UPS model: WKS Circle, Growatt, Victron, Deye, Sofar, Huawei, other...
• Location of use: ☐ Attic ☐ Stairwell ☐ Shed/Garage ☐ Basement ☐ Outside
• Application: ☐ Self-consumption ☐ Backup ☐ Cladding ☐ Resale
• Installation address: Country, Town (to check climatic conditions)
• Battery unused >6 months: Yes / No
• Detailed description of fault: precise symptoms, date of appearance, photos if available

Documents to be attached

1. Full logs: files _history.txt and _event.txt (original .txt format)
2. Completedtechnical form (Word/PDF)
3. Original purchase invoice (Wattuneed invoice or authorised dealer)
4. Photos of the fault if visible (swelling, leakage, physical damage)
5. System configuration: diagram or description of the installation (number of batteries, inverter model, cabling)

4.2 Examples of Defects Covered by the Warranty

4.3 Processing and lead times

Once the complete file is sent to Pylontech (via Wattuneed or directly) :

• Initial analysis: 1-2 weeks (check consistency of logs + form)
• Request for additional information: possible if file incomplete
• Guarantee decision: 2-4 weeks after receipt of complete file
• Replacement/repair: 4-8 weeks (depending on location and stock availability)

⚠️ Critical Point: If the logs show repeated overloads (pack voltages >54V for nominal 48V), Pylontech will refuse the warranty and will attribute the fault to incorrect inverter settings. Hence the importance of checking the settings BEFORE submitting a claim.

4.4 Wattuneed Support: Warranty Support

Wattuneed offers a free support service for Pylontech warranty claims:

• Pre-analysis of logs: our technicians check the consistency of the file before sending it.
• Form drafting: assistance to complete the technical form correctly
• Interface with Pylontech: we manage communication with the manufacturer (saves time, answers in French)
• Equipment loan: recovery cable on loan free of charge (security deposit).

Frequently Asked Questions (FAQ)

1. How often should I extract the logs from my Pylontech batteries?

Answer: In normal operation, an annual extraction is sufficient (during the maintenance check). In the event of abnormal symptoms (frequent alarms, reduced capacity), extract the logs immediately for diagnosis. The logs are overwritten after 1800 recordings (limited history).

2. Can I use a standard RS232-USB cable to retrieve the logs?

Answer: No. The Console port on Pylontech batteries requires a cable with specific logic level conversion. A standard RS232 cable will not work and could damage the BMS. Use only the official cables available from Wattuneed for your model.

3. Can DC balancing damage my battery?

Answer: No, if you strictly respect the voltages and currents indicated in the Pylontech documentation. DC balancing is an official procedure recommended by the manufacturer. Warning: never exceed 56V for a 48V nominal battery, and limit the current to 5A maximum.

4. My inverter is set to 53.5V but I still get OV alarms. Why does this happen?

Answer: The OV alarm is triggered at individual cell level (threshold 3.65V), not at pack level. If one cell is unbalanced (higher than the others), it will reach 3.65V while the pack is only at 52-53V. Solution: complete DC balancing.

5. How long does full DC balancing take?

Answer: Allow between 4 and 12 hours for complete balancing (3 stages). The duration depends on the initial imbalance. A 50 mV imbalance takes ~2h, a 300 mV imbalance can take 8-10h. Never exceed 12 consecutive hours at 0.3A.

6. Can I mix US2000, US3000 and US5000 batteries in the same system?

Answer: Yes, Pylontech 48V batteries are compatible with each other, but in order of priority: US5000 > UP5000 / US3000C / US2000C > US3000 / US2000. The US5000 battery must be the master (Link Port 0 empty). Always mention this mix in the warranty form.

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