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Keith Arnold avatar image
Keith Arnold asked

What can I adjust in ESS to improve SOC accuracy?

About 6 AM or some time after when charging starts the SOC jump higher. Note that although it shows 100 % the Battery is still happy to accept charge.

i have 4 kW Fronius on AC1 out. 250/70 with 8x370 Wp panels on DC, CCGX, Multi 5000, 2 EMS 48100 batteries (100 Ah each)

On a previous subject about specifying a discharge rate i agree now that inverter limit is not going to work. i would like that at the multi limit, 4 kW but would like to specify how much can come from battery. obviously while grid is on.

system is 17_Perth. appreciate a comment on the recorded data.

SOC
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2 Answers
Riaan Barkhuizen avatar image
Riaan Barkhuizen answered ·

Hi @Keith Arnold.

It is normal to see charge going into the battery even at 100% SoC. With Lithium batteries, you also need to watch the voltage value. So for instance you can get into a situation where the bms gives 100% reading from 55.2V but will only be completely charged at say 55.8V, after the 55.2V mark the quattro will be in "absorption" mode as opposed to "bulk".

The limit inverter power function will limit the amount of draw from the battery while the grid is on. The limit is ignored in case of a grid failure. There was a time when limit inverter power also limited the charge controller behaviour (so watch-out) for that scenario.

Best Regards

Riaan


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Keith Arnold avatar image Keith Arnold commented ·

Thanks. These are 53.5 and 51 float but I get your point.

in connection with inverter limit is fine if there is no dc mppt, then I gree. However, when there is a mppt you would still want all the solar to be put through the inverter while limiting discharge to a value. So if I want to limit discharge to 40 A the inverter limit is about 2000 W but I have an additional 2000W from PV. So I want to limit discharge to 40 A and put no limit on the inverter, 4000 so I use full PV and battery power.

i know this is not the first time it has been discussed, maybe some day Victron will put it on the to do list. Discharge limit and inverter limit are different when there are multiple dc sources feeding into the inverter.

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Riaan Barkhuizen avatar image Riaan Barkhuizen Keith Arnold commented ·

Hi @Keith Arnold

It is due to this complication you mention that I mostly use AC-Coupled systems, since with a charge controller, the limit is active for both charging and discharging. I noticed this problem the first time around Jun '19, and thought that it has been resolved since then via CGX firmware updates?

Running v2.32 of the CGX firmware, I'm having success with limit inverter power and still getting the full function out of the solar chargers (in this case a 250/100)

Solar Production


Cinsumption with limited power from the battery

This application is achieved with limit inverter power.


Best Regards
Riaan

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Keith Arnold avatar image Keith Arnold commented ·

Oop i wrote a answer rather than a comment. Want to double battery but my supplier ran away with the money and has not delivered.

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Keith Arnold avatar image
Keith Arnold answered ·

Hi see my version is 2.42



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