YORK YMC2 — UPS - BATTERY NOT CONNECTED

The OptiView Control Center shows UPS - BATTERY NOT CONNECTED. The manual lists it among the safety shutdown messages, so it is a safety fault rather than a plain notice. It is closely tied to the warning Warning - UPS - Battery Not Connected, which the manual describes as an auto reset warning built on the same battery voltage monitoring.

The control stores the minimum and maximum Battery Voltage that occurs within each 10 second window. At the end of each window, if the difference between the minimum and maximum battery voltage is greater than 0.5 V, a counter — the Battery Disconnected Counter — is increased; if the difference is less than 0.5 V, the counter is reset to 0. The intent is that 4 consecutive 10 second windows of battery voltage fluctuations indicate the UPS battery is not connected. Because this is a safety fault, it initiates a soft shutdown if it is set while the chiller state is Running.

• The chiller state is Running or Soft Shutdown, Battery Voltage Faults is enabled, and the Warning - UPS - Battery Not Connected warning has been set for 10 continuous minutes.
• The chiller state is Stopped, Battery Voltage Faults is enabled, and the Battery Disconnected Counter is 4 or more.
• Behind both paths: battery voltage fluctuations — a minimum-to-maximum difference greater than 0.5 V within a 10 second window — raise the Battery Disconnected Counter.

1. Check whether Battery Voltage Faults is enabled. The safety can only be set while it is enabled, and disabling it is one of the release conditions.
2. Note the chiller state shown by the control (Running, Soft Shutdown or Stopped), because the set conditions differ by state.
3. If the chiller was Running or in Soft Shutdown, check how long the Warning - UPS - Battery Not Connected warning had been set; the safety follows 10 continuous minutes of that warning.
4. If the chiller was Stopped, check the Battery Disconnected Counter; the safety sets once it reaches 4.
5. Watch the battery voltage readings: a difference greater than 0.5 V between the minimum and maximum within a 10 second window increases the counter, while a difference less than 0.5 V resets it to 0.

• 10 seconds — the window over which the minimum and maximum Battery Voltage are stored.
• 0.5 V — the minimum-to-maximum battery voltage difference within a window that increases the Battery Disconnected Counter; a difference less than 0.5 V resets the counter to 0.
• Battery Disconnected Counter of 4 or more — sets the warning, and sets the safety directly during chiller state Stopped.
• 10 continuous minutes — how long the warning must be set before the safety sets during chiller state Running or Soft Shutdown.
• 60 continuous seconds — how long the counter must stay at 0 for the warning to be released.

The safety is released when any of the following is true: Battery Voltage Faults is Disabled, or the Battery Disconnected Counter is 0. The associated warning is an auto reset warning and is released when the Battery Disconnected Counter is 0 for 60 continuous seconds. The manual lists no separate manual reset step for this safety fault.