Battery Management System
Battery Management System Protections
The Battery Management System’s (BMS) primary function is to monitor cell module voltage, temperature, and battery current. The BMS uses this information to maintain cell operation within operating specifications. If a parameter falls outside of operating specifications, the BMS will disconnect and protect the battery from:
Overvoltage: Charge voltages that are too high.
Undervoltage: Discharged voltage that is too low.
Overcurrent: Current is too high when powering up a load (high inrush current) or from a sustained charging or discharging current above the specified limit.
Over-temperature: Cell temperature that is too high during charge and discharge.
Under-temperature: Cell temperature that is too low during charge and discharge.
Load Qualification: Protection may occur when switching the battery ON. The protection qualifies the load attached to it to prevent switching ON into a reverse polarity, short circuit, mixed voltage system, or large capacitive load.
For trigger and recovery values, refer to the table in the Protection Specifications topic.
The BMS reconnects when it hits recovery thresholds. Manually switch the battery ON if the BMS disconnects due to low voltage protection. If a low-voltage fault is constantly affecting the system, there may be a constant parasitic draw. To prevent the low-voltage fault when the battery is not in use, a physical disconnect switch is recommended.
After a load qualification fault, there is a 120-second delay until you can switch ON the battery again.
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BMS Pre-Charge System
Turn on all batteries in the battery bank before energizing any inverter-chargers to prevent tripping a breaker in the battery bank while pre-charging the system.
The battery has a Pre-Charge System to energize external capacitive loads before switching the main relay ON. The maximum input capacitance for a single battery should not exceed the values in the table in the Electrical Specifications topic.
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BATTERY FAULT
Failure to follow these instructions may result in equipment damage. |
Battery Management System Load Qualification
When the battery switches from the OFF state to the ON state, the battery BMS will qualify the external load before switching ON the main relay. Load qualification will reject switching ON into short circuit, reverse polarity, mixed voltage systems, or capacitive loads that exceed the battery’s limits.
The battery will attempt Load Qualification up to 10 times. After ten failed attempts at Load Qualification, the battery switches OFF.
During Load Qualification, or when a load is disqualified, the ON/OFF key flashes.
Battery Management System Cell Balancing
The cell balancing circuits in the battery compare all cells in a battery and balance the cell voltage at the end of the charge. When there is a network of batteries over the LYNK port, all battery cells are balanced as an entire system, not as individual batteries.
Battery Charge and Discharge Settings
The HELIOS ESS supports direct closed-loop communication with some brands of power conversion devices. Other types of inverters, such as Schneider XW+ and XW Pro with Xanbus, require a LYNK Communication Gateway. In addition to communication, the LYNK II provides other benefits such as monitoring, diagnostics, programmable relays, and LYNK CLOUD. For further information, please refer to the LYNK II Gateway Communication User Manual available from the discoverenergysys.com website, or contact your Discover provider for assistance.
Refer to the appropriate LYNK II Communication Gateway Application Note available from discoverenergysys.com for the set up of closed-loop parameters and integration with specific brands of solar inverter-chargers and solar charger controllers.