DISCOVER ELEMENT - Theory of Operation

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7.2 Internal Heating (48-48-5120-H)
The battery module with part number 48-48-5120-H is equipped with internal
heating. When the battery module’s internal temperature is below 5°C (41°F) and the
battery module is connected to a charging source, energy is diverted to the internal
heating element to avoid the under-temperature fault.
The heating stops when:
1. The battery module’s internal temperature reaches 8°C (46.4°F).
• Once the cell temperature reaches this threshold, all the energy is directed to
charging the cells.
2. A discharge current of 250 mA or more is detected for 10 minutes.
• After the heating stops, if the battery module’s internal temperature drops
below 5°C (41°F) and the battery module is connected to a charging source,
the heater turns ON again.
When internal heating is active, discharging the battery is not possible.
For information about internal heating, refer to Section 3.4, Protections Specifications,
and Section 3.5, Internal Heating Specifications.
NOTE
Charging and heating can occur simultaneously. However, the BMS will not allow
charging to continue when cell temperature is below 0°C (32°F) for 5 seconds.
7.3 Battery Management System
7.3.1 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 module
from:
1. Overvoltage: Charge voltages that are too high.
2. Undervoltage: Discharged voltage that is too low.
3. 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.
4. Over-temperature: Cell temperature that is too high during charge and discharge.
5. Under-temperature: Cell temperature that is too low during charge and
discharge.
6. Load Qualification: Protection may occur when switching the battery module
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 Table 3-4, ELEMENT ESS Protection
Specifications.