Dear All

I am writing to report a critical overvoltage issue in my solar energy storage system and request urgent technical assistance.

System Configuration:

• Batteries: 4x PylonTech US5000 (parallel connection, CAN protocol).

• Inverter: Deye SUN-8K-SG01HP2-US-AM2.

• Communication: CAN/BMS protocol enabled, no explicit errors logged.

Issue Description:

• During charging, the battery via grid voltage spiked to 56.94V, exceeding the US5000’s maximum safe limit (53.5V - 56.80).

• The Deye inverter halted charging automatically during the event.

• No communication errors or overcharge alerts were reported by the inverter.

Troubleshooting Steps Taken:

1. Verified inverter settings:

   • Charging voltage limited to 53.5V - 56.80 (PylonTech lithium profile).

   • CAN protocol confirmed active.

   • Addresses set correctly (1–4) for parallel configuration.

2. Tested communication cables

Request:

• Please provide guidance to:

  • Diagnose potential BMS or communication failures.

Thank you for your urgent attention to this safety-critical matter.

I am struggling to find the question, since you stated there were no errors.

The voltage that was reached is pretty high for a 15 cell pack, max should be 54.75, and safe 51.75

You might have destroyed the longevity of the pack, and potentially severely brought down the overall AH.

Perhaps send it into a service center and have then investigate, if only one cell is damaged, and they can replace it before the rest gets damaged, that might be wise.

The inverter charging profile applies to 16 cells, you are allowed a maximum of 53.5V. See attachment

https://energy.ironws.com/batteries/optimizing-lifepo4-battery-settings-for-inverters/

Use USER (US) setting for the battery. The link sent describes how to charge a 15 cell battery pack. (I don't think the cells are damaged, the built-in BMS is responsible for protecting against overcharging..) Good luck