Adding New Battery Modules to an Existing HV Battery Rack

WHEN ADDING EXTRA HV BATTERIES TO A PREEXISTING HV BATTERY RACK THE MINIMUM NUMBER OF BATTERIES FOR EXPANSION IS FOUR.

For example:

Increasing from 4 battery modules to 8 or more battery modules ✅

Increasing from 6 battery modules to 10 or more battery modules ✅

Increasing from 4 battery modules to 6 battery modules ❌

Increasing from 10 battery modules to 12 battery modules ❌

This is because the batteries must be charged independently before being added to the stack and the minimum required number of battery modules to power the battery management unit (BMU) is 4. Failure to balance the batteries can cause SOC misreporting and SOC spikes and can lead to batteries becoming overdischared which requires a lengthy recovery process.

When installing the additional modules:

1. Charge the pre-existing battery modules in your HV battery stack to 100% SOC, from either PV or AC.
2. Power off the system and remove the pre-existing batteries from the rack and add your 4 OR MORE batteries to the rack and connect to the BMU.
3. Adjust the BMU number accordingly (accessed on the BMU display by pressing the icon of a person and entering password 123) for this amount of batteries to ensure correct communications.
4. Charge these batteries also to 100% SOC, from either PV or AC.
5. Power off the system and add the original batteries to the stack.
6. Power the system back on and ensure you update the BMU number again for the  correct number of batteries in the rack.
7. Ensure your batteries are charged regularly to 100% (roughly ever 7 to 10 days) as this is when the BMU will refresh and recalibrate the combined SOC percentage.

*Additionally when adding battery modules to a pre-existing stack we do not advise existing stacks of battery modules that have undergone a large number of charge cycles be expanded. This is because the overall cycle count will be shown as the average of all of the connected battery modules in the stack.