Battery voltage limits in ESS mode? (not discharging below 41V when grid available)

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boekel asked Dec 16, '18

Battery voltage limits in ESS mode? (not discharging below 41V when grid available)

I'm testing batteries with an ESS system: Quattro 48/10000, Venus, CANbus BMS

When testing 12s batteries, in ESS mode the system discharges until about 41 volts, then tapering down DC current and holding voltage there. I've searched for sustain voltage, cut off voltage, etc., all is set to 36/37 volt.

when adding a load to the output, the unit uses grid-power to provide the load, actually going over the set Input Current limit.

Only when switching off the Grid, the system uses the battery down to the set levels (stopping at 37V)

Is there a setting somewhere I missed? or is it an undocumented feature?

some lithium batteries have quite a bit of capacity between 41 and 37 volts, it's good to know if we're able to use this in peak-shaving systems.

ESS

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lassestu commented · Apr 22, 2019 at 10:29 AM

Did you find a solution for this? Having the same problem, starts using grid power from 41-40.8V. Only when I put the grid down it starts using battery power again all the way down to 37.2V which is acceptable.

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boekel ♦ lassestu commented · Apr 22, 2019 at 05:58 PM

No I have not, in practice I only use this part of SOC for backup use, so not a problem in real life for me.

But it would be nice if the system works as expected.

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lassestu boekel ♦ commented · Apr 22, 2019 at 09:04 PM

Yeah I guess my system will be at the same level, the rest will be for real backup if the grid actually goes down. But I would like to know what parameter is limiting this, I cant find it in any documentation, so I would appreciate if any Victron staff replies with what parameter that is doing this, and why its not customizable.

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Modifications Space

Node Red Space

Answer 1 · 2018-12-16T21:45:14Z

Guy Stewart (Victron Community Manager) answered · Dec 16, 2018 at 09:45 PM

There are several places where settings or limitations could lead to this behaviour.

Could you please post screenshots of the following sections for your system?

Venus-device / CANbus Battery / Parameters

Venus-device / ESS / Minimum SOC

VE Configure / ESS Assistant / Sustain voltage

screen-shot-2018-12-17-at-84146-am.jpg (97.2 KiB)

screen-shot-2018-12-17-at-84045-am.jpg (109.5 KiB)

screen-shot-2018-12-17-at-83859-am.jpg (92.3 KiB)

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Answer 2 · 2018-12-18T21:37:10Z

boekel answered · Dec 18, 2018 at 09:37 PM

Some settings and observations:

screenshot-2018-12-16-153354.png (40.5 KiB)

screenshot-2018-12-16-153401.png (19.3 KiB)

screenshot-2018-12-18-205010.png (37.9 KiB)

screenshot-2018-12-18-205025.png (50.5 KiB)

screenshot-2018-12-18-223340.png (47.7 KiB)

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Answer 3 · 2021-05-29T12:39:47Z

markde answered · May 29, 2021 at 12:39 PM

hi,

Could anyone find a solution to drain the battery down to 37.2 voltage while running in ess mode? Hardware wise it should be possible because without Grid it discharges all the way down.

thx in advance!

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solartech12 commented · Mar 01, 2022 at 12:17 AM

did you find solution to this ??

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