E9
Einhell Battery Overvoltage / Temperature Protection

Robot lawnmower displays E9 and will not start; sometimes after storage or long inactivity.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Battery too hot from recent charging or ambient heat, Battery temperature sensor fault, Incorrect replacement battery installed, Charging station overcharging due to control fault

How to Fix / Troubleshooting

Safety first: Turn OFF the mower and disconnect the charging station from mains.

  • Allow cooling: Move the mower and charging station to a shaded, cool area. Let the mower sit for at least 1 hour to allow the battery to reach ambient temperature.
  • Check environment: Ensure the charging station is not installed in direct sunlight or near heat sources. High temperatures can trigger protection circuits.
  • Inspect battery type: If the battery was recently replaced, verify that it is the correct Einhell specification (voltage and chemistry). Incorrect packs can cause overvoltage errors.
  • Check temperature sensor wiring: If accessible, inspect the small temperature sensor cable attached to the battery pack. Ensure it is not broken or disconnected from the mainboard.
  • Test again: Reconnect power and attempt to start the mower. If E9 persists, the battery pack or charging electronics may be defective and should be replaced.
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Repair Difficulty

Medium 3/5

Required Part

Battery Pack
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