E17
Zaptec
Load Balancing Bus Communication Fault
Charger shows E17; app indicates ‘Load balancing communication error’ in multi-charger installation
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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
Broken or miswired RS-485 / bus cable between chargers, Incorrect termination or addressing, Faulty load balancing controller, Firmware incompatibility between units
How to Fix / Troubleshooting
Safety first: Ensure all chargers in the group are de-energized before modifying bus wiring.
Steps:
- Check physical bus wiring: Inspect the daisy-chain cable between Zaptec chargers for damage, loose terminals, or reversed polarity.
- Verify termination: Ensure termination resistors are installed only at the ends of the bus as per Zaptec guidelines.
- Check addresses: Confirm each charger has a unique address or role in the load balancing group.
- Firmware alignment: Update all chargers in the group to the same firmware version.
- If one unit always shows E17: Suspect a faulty communication interface on that charger’s main control board.
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Repair Difficulty
Hard
4/5
Required Part
Load Balancing Communication Interface
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