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3. Charge to 61.5V.
4. Repeat this process up to 4 times or until SOC is corrected.
If SOC has still not been corrected after attempting the above process, please contact
BMZ.
2.10
Off-Grid Systems, Battery SOC and Running Generators
1. My system is Off-Grid and the max voltage I see on the batteries is 60.5.
A.
You likely have a Sunny Island inverter.
In off-grid mode, the Sunny Island will reduce the max charge voltage for batteries down
by 1V. (this originates from conditions with lead-acid batteries)
If you read the previous section, you see the voltage required to complete a learning cycle
is 61.5V.
What can you do?
If the system is off-grid and connected with a generator, the generator can be used to
charge the battery through the Sunny Island. You will likely need to manually run the
generator for charging.
B.
There is a setting on the 3.01 firmware and service tool that allows adjusting of the charge
voltage for the battery. However, this should only ever be used for batteries which stay
off-grid. While a battery set for off-grid charging is not a hazard if brought on grid, it's
possible the lifetime will degrade at a much faster pace or protections will trigger at the
very end of a charge cycle.
As of August 2020, this firmware is not on every battery by default, so please contact BMZ
if you are interested in this firmware and you are off-grid.
2.11
Battery Capacity Issues
BMZ ESS have both nominal and usable capacity listed in the product literature. For actual usage, usable
capacity will always be the value used.
1. I get a lower amount of capacity from the battery than expected
A.
There are several factors to consider when figuring out the amount of energy you are able
to get from and put into the ESS battery, however two major items are:
-
The battery itself is above 95% efficient, however that still means you are losing a
couple percent of the overall energy input/output to that.
-
The inverter is the other major item which causes energy loss. Its possible they can
reach greater than 95% efficiency, but if only a fraction of the rated inverter power is
being used, the efficiency of the inverter will drop.
The power usage for the inverter will also contribute to a reduced energy through-
put. For example, depending on the inverter, over the course of 24 hours, an inverter
might use up to half a kilowatt-hour to stay operational; this doesn't even account for
its overall efficiency.
B.
If the battery is older, than its expected that usable capacity will be reduced compared to
any new battery. This will be true of any battery on the market.
Page 12 of 14
Version 1.01
ESS Troubleshooting Guide
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