question

Kristof G. avatar image
Kristof G. asked

DVCC behavior

Hi all,


i have something wierd going on.


DC Feed-in on = voltage goes to +0.4v ( what is normal in the manual )

so when i setup my ve.config charger absorption voltage to 56v and DVCC 56v it goes to 56.4v a 56.8v ( is to high for me , lithium bateries)

i want to charge with 56v max. and do DC feed-in

( i have one installation , where there are lead acid batteries , and the voltage stays at 60v even with DC-feed-in on.. but what the hell...)


so i played around , lowered the DVCC voltage to 55.6v , still goes to 56.4v a 56.8v

than i changed the ve.config charger abs. voltage to 55.6v and what do we see... yes 56v ( w00t w00t ), you think all is ok.


BUT than when i disable DC-feed-in .. DVCC still on 56v and ve.config charger on 55.6v == indeed goes to 55.6v abs.


so for me the DVCC does not work.

or is it my wierd brain ?


https://nextcloud.kg666.org/s/zJXYQLcE5e9fRSk

https://nextcloud.kg666.org/s/FnRm3iHMQKgeqK7

https://nextcloud.kg666.org/s/dqJejk3gFqb6w9L


P.S. the system iam talking about , where the voltage stays at 60v ( everything setup @ 60v, ve.config charger / DVCC ) and DC-feed-in enabled = is a 3 phase multi-plus II 5000 system.

my system is a single quattro 8kva ( will change to multi-plus II 5000 later )


DVCC
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4 Answers
nickdb avatar image
nickdb answered ·

What GX version are you using?

Are there any modifications, third party drivers, nodered etc?

You don't seem to have a battery listed in the device list?

I only see a shunt, so is it a unmanaged lithium ie no CAN connection from the BMS and it doesn't appear in the cerbo list?

The DVCC voltage limit is clearly marked as managed batteries only, if you only have a shunt it is not going to work. Your system will effectively behave the same as a lead battery.

(This setting is also not designed for permanent use as per the manual it is for correcting severe imbalances)

Limit charge current is also ignored with DC export enabled.

Do you have temperature compensation enabled on any devices/inverter?

With this setup the inverter charge algorithm is followed.


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Kristof G. avatar image
Kristof G. answered ·

hi @nickdb ,

Your answer did lett me think about something ...


What GX version are you using? Cerbo gx - last firmware ( no beta )

Are there any modifications, third party drivers, nodered etc? Nothing

You don't seem to have a battery listed in the device list?

its indeed a 3th party bms system ( seplos ) , CAN connection to the Cerbo GX

I only see a shunt, so is it a unmanaged lithium ie no CAN connection from the BMS and it doesn't appear in the cerbo list? CAN connection and Cerbo gx sees the BMS

Do you have temperature compensation enabled on any devices/inverter? No




Controlling BMS , was set to "no bms control"

when i set this to the bms i have... its charging to 56v correctly , and the DC feed-in set on => 56.40v and the ve.config charger is still set to 55.6v , so there you are right! ( thanks )


and bonus , the DVCC is indeed working now..


the only wied thing is , that i saw on my lead acid installation , the voltage is set to 60v and even with DC feed-in , it stays on 60v , not 60.4v


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nickdb avatar image nickdb ♦♦ commented ·
On the VRM device list pic you posted, the battery isn't listed, only the shunt. Any CAN connected battery should appear in that device list.

Glad there is progress, without it being set as the BMS, DVCC wouldn't work well.

Make sure it is also configured in the GX system setup as the battery monitor.

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Kristof G. avatar image
Kristof G. answered ·

@nickdb correct , the first list was from the victron update list, sorry

its on the list of devices

https://nextcloud.kg666.org/s/JwykirjMEM9t85J


Make sure it is also configured in the GX system setup as the battery monitor.

i understand, but the lynx is much beter in calculating everything and drifts less, so thats why i did not set it as battery monitor.

there must be a reason i did not setup the BMS in control of everything .. but i do not know why anymore ...

maybe i will set the gridpoint via modbus in Home Assistant and lett HA check every 15min. to some parameters

OR

i put 55.60 as absorption voltage and DC-feedin will be 56v in de summer and in the winter 55.60v



thanks for your input @nickdb

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Kristof G. avatar image
Kristof G. answered ·

Maybe interesting for other users.. with the "0.4v extra problem."


i have somethings tested out today ...


when you limit the feed-in to lets say 1kw ( and you have 14kw of DC power ) , the 0.4v will add to your total voltage.. BUT when you do not block , so letts say feed-in put to 16kw and you have 10kw of sunpower ... the voltage wil just stay at the normal voltage DVCC 56v for example.


just info for someone who is interested ;-)



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nickdb avatar image nickdb ♦♦ commented ·

Yes, to push max loads into grid, the overvoltage is required to keep chargers producing optimally.

When you actually have to throttle generation, then, it is no longer necessary.

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Related Resources

DVCC chapter in GX manual