15.1 Basic Information

15.2 Phenomenon

1. The machine cannot be charged and displays E51 error

   APP Prompt: Charging Not Detected (E51). The E51 error usually occurs when the robot fails to properly detect the charging process, and further inspection of the charging pile, charging contacts, and the contact between the robot and the charging pile is required.

2. The machine intermittently powers on and off, or fails to charge immediately after completing the mowing task (i. e., the battery BMS causes abnormal charging detection)

15.3 Possible Reasons

1. The charging pile is not powered on properly
2. Foreign matter or moisture is present on the surface of the charging contact
3. The charging shrapnel fails to spring back / cannot make full contact with the charging contact
4. Moisture detected by the sensor at the bottom of the charging pile
5. The leakage current of the anti-reverse diode in the battery BMS will increase as the temperature rises, and this increased leakage current will interfere with the charging detection, resulting in abnormal charging detection.

15.4 Troubleshooting Steps

1. Check the power supply of the charging pile

Indicator Status Description of Charging Pile: Button Functions, Device and Charging Pile Light Signals

Confirm that the charging pile is properly powered on, and there are no abnormalities in the power adapter and connecting cables.

1. Set the multimeter to the voltage range
2. In the direction shown in the figure, connect the positive (red) test lead to PIN2 and the negative (black) test lead to PIN1
3. If the multimeter displays a voltage of around 39V, the charging pile is normal; if it displays a voltage in any other range or a negative voltage, the charging pile is abnormal.

2. Check the charging contacts

• Machine charging contact
• Charging shrapnel for charging piles
• Check for dirt, foreign objects or moisture
• Whether the shrapnel can rebound normally
• Whether the contacts on both sides can make full contact after the machine stops

In some user cases, even if the contact surface appears relatively clean, the charging shrapnel itself may still affect the contact, so it is necessary to further check the actual contact between the shrapnel and the contact. Even if a dock shows the expected voltage, it may still fail to charge because of poor contact, damaged connectors, or excessive contact resistance.

3. Check for overwetting

Check whether the charging pile is equipped with a humidity/water ingress detection area at the bottom. If the charging pile detects water ingress or excessive humidity (which will trigger the rainwater immersion light effect where the middle indicator stays on steadily and the indicators on both sides flash), it may also result in failure to charge properly.

Excessive moisture at the bottom of the Plus machine charging pile The red circle indicates the position of the humidity sensor

4. Restart the machine and the charging pile

After powering off and restarting the machine, let it redock for charging and check whether the E51 fault is resolved.

5. still cannot be resolved

If it is confirmed that:

• The charging pile is operating normally with power supply
• The contacts are clean and make proper contact
• No over-wetting
• Error E51 persists after restart

15.5 Solutions

1. If the power adapter or connection cable is damaged, please contact Lymow Support for further assistance.
2. After thorough cleaning, power off and restart the device before attempting to charge it again.
3. Apply only the specific conductive thermal grease model/specification approved by Lymow on the electrode tab.
4. Move the charging pile to another relatively dry area

If the issue persists after following the steps above, please contact Lymow Support Center at support@lymow.com with the following information:

• Order ID/Purchase Invoice
• Device serial number (SN)
• Troubleshooting results (with photos)
• Time the issue occurred

We will follow up as soon as possible and provide a solution.