DVCC: "Max Charge Voltage" not considered when ESS in "keep batteries charged" mode?

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andreas-0676 asked Apr 30, '22

DVCC: "Max Charge Voltage" not considered when ESS in "keep batteries charged" mode?

Dear all,

I'm using ESS on a Multiplus 2. I've gone already to related posts in:

https://community.victronenergy.com/questions/11225/dvcc-and-pylontech-battery.html
https://community.victronenergy.com/questions/16064/battery-monitor512-alarm-high-voltage-alarms-victr.html
and I've configured the system according to: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

My Problem:

When I operate ESS in "keep batteries charged" mode, I get "High DC ripple" Alarms and "High Voltage" Alarms leading to shut down the Multiplus at high solar yields (as already described in other posts), even though I've set the "Max Charge Voltage" in DVCC to 51,7 or even less.
Observing the local terminal, I can see charging current although the battery voltage is above 51,7.

When I operate ESS in "Optimized with Battery life" mode, I don’t get Alarms nor shut downs. At the local terminal I can see even discharge currents in case the battery voltage exceeded the limit set in DVCC (after changing from "keep batteries charged" to "Optimized with Battery life" mode).

From what I've seen it appears to me DVCC limits are being not obeyed when operating ESS in "keep batteries charged" mode?

Anyone having similar problems respectively is there any solution to stable- and reliably run ESS in "keep batteries charged" mode ?

BR Andreas

My HW configuration is:

Multiplus-II 48/3000/35-32
Venus GX Firmware: v2.73
4 x Pylontech US2000C Firmware: v2.7
SMA SunnyBoy on AC-Out 1

ESS DVCC overvoltage

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Answer 1 · 2022-04-30T12:21:43Z

Guy Stewart (Victron Community Manager) answered · Apr 30, 2022 at 12:21 PM

Hi @Andreas 0676,

There have been improvements to DVCC in Venus firmware since version 2.73.

First thing I would do is make sure all the components are running their latest firmware version in case it's an issue that is already fixed.

5

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andreas-0676 commented · May 01, 2022 at 07:41 AM

Hello Guy,

thanks for the fast reply! That's why I've become a Victron fan: excellent- engineers and products!

On the subject I've upgraded the Venus firmware to 2.85, and at least what I can see from the reported values, DVCC restrictions are now being respected.
Once the problem occurs again, would come back again otherwise thank you very much for the support!

BR

Andreas

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andreas-0676 commented · May 04, 2022 at 11:35 AM

Hi Guy,

I've upgraded the Venus firmware to 2.85 and the Multiplus firmware to 4.96,
now both are on the latest version!

However, the problem seem to still exist, in case there are high solar yields on AC1.

In case I'm running ESS on "keep batteries charged" the DVCC limits are not respected.
While the Multiplus is in "Absorbtion" mode, I see a charging current continously charging the batteries, until I get a "high battery voltage" Alarm or even a shutdown.

In case I do change ESS to "optimized with battery life" while the battery voltage is above the DVCC charge voltage limit and the Multiplus is in "Absorbtion" mode, the Multiplus changes to "Discharging" and the battery will be discharged.

Any suggestion or bugfix for this subject?

BR

Andreas

Update: added some Measurments from VRM portal:

Bildschirmfoto vom 2022-05-09 12-24-59.png

Update 2: Added another chart from VRM portal:

I assume once the CCL is set by the BMS one can see an intented charging?
Once the Solar power ist available on AC1-Out, one can see ocassionally charging
current, even though the CCL is still 0, I think this is not intended even it does creat problems
then out of the sudden, one the charging current is going up, without a reason, until "High Voltage Alarms" are released. Without manuell changing the ESS mode, the system would shout down itself.

Anyone having similar issues or a solution?

0 ·

bildschirmfoto-vom-2022-05-09-11-49-25.png (198.0 KiB)

bildschirmfoto-vom-2022-05-10-14-48-17png.jpg (191.8 KiB)

nickdb ♦♦ andreas-0676 commented · May 09, 2022 at 10:04 AM

This is normal. If you read my post, below, you will understand that keep charged will target above CVL, your charts seem consistent with that. The slight increase is not a problem for the battery, but if your cells are imbalanced it will trigger a warning until they balance - all normal.

When you change modes the voltage will revert to CVL and because the actual voltage is above this, mppt's will go to sleep until the voltage drops beneath the CVL by discharging the battery.

All to be expected.

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andreas-0676 nickdb ♦♦ commented · May 09, 2022 at 10:45 AM

Hi nickdb,

thanks for the reply. However,

a.) I'm not having a DC coupled system with MPPT's, so I'm not sure the subject as you explained, can be applied to my configuration.
b.) The problem is an "escalating" process! In case I don't leave the "keep batteries charged" mode.

first stage getting a "High Voltage" warning
second stages is getting a "High DC ripple warning" (that's the reason why I swichted to "optimized with battery life" again
The Multiplus II swiches off!

I assume that's not an expected behaviour?

BR

Andreas

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andreas-0676 commented · May 20, 2022 at 08:53 AM

Hello,

any update on the subject?

I'm now using the ESS Mode "optimized with battery life" with min SOC 100% as suggested work around in one of the previous firmware version. However can someone confirm the problem respectively is there a fix in future?

BR

Andreas

0 ·

Answer 2 · 2022-04-30T14:46:30Z

nickdb answered · Apr 30, 2022 at 02:46 PM

With keep batteries charged, the mppt will target 0.4V higher than the batteries CVL.

This should make no difference to the batteries unless you have imbalanced cells.

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Answer 3 · 2023-05-15T22:48:25Z

alberto-fernandez answered · May 15, 2023 at 10:48 PM

Im having the exact same issue, I'm aware of a cell imbalance of my pylontec US3000C due to the high amount of batteries (40x batteries in strings of 4), I started using keep batteries charged due to recommendations on this forum, one day in the morning the PV (24kW, two Fronius Symo 12kW), started to charge the batteries even thought I already set limit voltage and limit current to (51VDC 10A) due to previous high voltage internal error on the DVCC menu, I noticed the PV wasnt stopping from charging and a high voltage alert did come off, and a total shutdown of my 3 inverter (3x 10kVA quattro inverters), I switched back to optimized with battery life and limited charging voltage and stepped up minimum SOC to 100%, Im going to step up charging voltage day by day with low currents so the batteries balance themselves, anyone have another recomendation for balancing cells?

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