question

solarhome avatar image

ESS mode - cycle battery

Hello technical specialist,
ESS mode, BMZ-battery, AC-output Fronius Primo, MPPT Smart Solar. All the latest updates.
The system works to offset surpluses and as a backup system with minimal SOC maintenance.
It is normal to see graphs that the battery cycles by +/- 3%.
If I have a minimum SOC of 60%, then the MPPT Solar power goes to the battery at about 63%.
Then the battery will be consumed and again 60% will start again.
Is this a normal system property of the ESS system?

Thank you for your time
Ondra

BMV Battery MonitorESSbattery chargingSOC
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3 Answers
solarhome avatar image
solarhome answered ·

the same problem with another installation and another battery manufacturer.
If I have a minimum SOC of 30%, then the MPPT Solar power goes to the battery at about 33%.
Then the battery will be consumed and again 30% will start again.
Is this a normal system property of the ESS system?



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You'll really need to provide more information..
-battery manufacturer / type or BMS brand / type
-show the BMS parameters when this happens
-what is your grid setpoint

Also: you've cropped the screenshots so we can't see the current.

it -might- be normal operation, battery get's charged a bit (I'd say 1,2V..), than discharge is allowed again until lower SOC setpoint is reached, etc.

The battery seems to react very fast in voltage VS current, is it lead-acid?

Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hello Solarhome,

I will be conducting a thorough real world test and updating the documentation for the BMZ some time in the next month, perhaps sooner. The battery should arrive to me tomorrow.

I should be able to give you some much better advice then.

In the mean time, would you mind if I look through the VRM for your site to see more closely what is going on?

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Hello Guy,
please write me your email:
dlabaja@solarhome.cz

Thank You for your time and support
Ondrej Dlabaja

boekel avatar image
boekel answered ·

What is set as battery monitor? and what are the parameters from the bms?
I -think- your battery is fully charged but SOC not correct.

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