Cold Temperature Operation of the Blue Ion ESS

When discussing the operating temperature of the Blue Planet Energy Blue Ion Energy Storage System (ESS), it is best to separate out the operations into storage, charge and discharge functions; as the architecture of the system allows for different temperature windows per function. 

The temperature range of the Blue Ion are as follows: 

Storage temperature -20°C to 45°C 

Charge temperature range 0°C to 45°C 

Discharge temperature range -20°C to 50°C 

The storage temperature window refers to when the batteries are not in regular service, whether this is during shipping, warehousing or even after installation in instances where the battery modules are not being charged/discharged by the Battery Management Unit (BMU) for extended periods. 

During normal operation, the BMU monitors many variables within each battery module and battery cell. One of these variables is the cell temperature, which is displayed in the Blue Ion Monitoring as “Min Cell Temp” and “Max Cell Temp”.

The Blue Ion ESS BMU has separate relays for both the charge and discharge functions. When the cell temperature falls below 0°C, the BMU will turn off the charge relay but will continue to allow the discharge relay to operate . This allows the system to remain operational for discharging even when the cell temperature is below 0°C. The BMU will allow the discharge relay to operate down to -20ºC. 

If the unit is under regular use the cell temperature is about 5-6º C above ambient temperature. This means that if the ambient room temperature drops below freezing, the unit will still be able to charge until the cells themselves register 0ºC. 

The BMU will automatically allow charging and discharging once the temperature comes back within operating parameters. 

This functionality will allow a properly designed system to survive through temporary cold spells until the heat (and sun) returns to the system allowing it to charge again. This is an autonomous feature of the Blue Ion BMU, and does not rely on communication with the inverter.

Find more information on this subject in the attached PDF.

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The information in this application note is provided “as is” without warranty of any kind, either express or implied, including, but not limited to, the implied warranties of fitness for a purpose, the warranty of non-infringement, or any warranties as to the information's accuracy or completeness. Blue Planet Energy reserves the right to make changes to the information available at any time and assumes no liability for applications assistance, customer product design or specific customer requirements. Nothing in this application note shall be construed as modifying any rights and obligations in the contract between the parties.