The Battery Soc Is Wrong; The Learning Cycle - BMZ ESS Troubleshooting Manual

Just as described in Section 2.5, you can remove the cables from the ports and by-pass
them.
If communication is successful, then the port is likely bad, contact BMZ for a replacement.
If communication is still unsuccessful, then something is likely wrong internally, contact
BMZ.
2.9

The Battery SOC is Wrong

1. I keep seeing the SOC jump around or I know its not right compared to the battery voltage.
A. This actually isn't an issue per se – the SOC is mostly a human facing value; the battery
will still discharge and charge even if it is not correct. However, this may be an issue for
the inverter if you have inverter settings react to the battery SOC
With that said, there is a defined reason as to why the SOC value appears incorrect.
2.9.1

The Learning Cycle:

All ESS batteries must go through a learning cycle. This calibrates the SOC and allows the
battery to learn its real capacity (true of any battery on the market, the actual capacity
versus the design capacity will vary a little) and become more efficient.
While the battery can continue to operate without completing a learning cycle, its
recommended to complete at least one learning cycle each month, more if possible.
Per the operations manual:
In this learning cycle, the battery must cover the SOC limits of 100% and 12% as frequently
as possible.
The learning cycle starts at 100% SOC (battery full) and ends at 12% SOC. If both incidents
occur in succession and, in the meantime, the energy is not charged more than 20% SOC,
then the learning cycle is evaluated as "successfully executed".
What this means is:
- You must charge the battery to 61.5V (SOC will automatically be set to 100%)
Then:
- Discharge to a voltage less than 47.25V (SOC will automatically be set to 12%).
- Charge back to 61.5V afterwards.
- Verify via the service tool these voltages have actually been reached; if not reached,
the learning cycle won't be completed.
This will calibrate the SOC, the real capacity, and if any batteries are connected in parallel,
ensure that they are synced up and at the same voltage.
Over time, its possible for the SOC to start drifting. Simply completing a learning cycle will
fix this.
Note: Normally, performing the learning cycle as described above will successfully
calibrate the SOC. However in some uncommon cases, sometimes the battery must have
a learning cycle performed multiple times in a row to properly calibrate the SOC.
If you find that after performing a learning cycle that the battery SOC has not been
adjusted close to what its expected value should be, attempt the following:
1. As described in the procedure above, make sure the battery is fully charged.
2. Discharge until voltage is under 47.25V.
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