Does enabling DVCC change other system parameters?

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ben asked Jan 23, '19

Does enabling DVCC change other system parameters?

On my (long-running) system, I recently enabled DVCC to use Shared Voltage Sense with my MPPT. I left the other DVCC features off.

Today I noticed that my Quattro had its DC max charge current reduced significantly from its normal setting (from 200A down to 50A). I certainly didn't load up VEconfigure and alter this setting, and the only other way for a user to change it is by writing to D-Bus manually I believe.

I seem to recall that maybe 50A is the *default* max charge current on this Quattro. So I am now curious whether enabling DVCC somehow caused this value to be overwritten.

DVCC

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Answer 1 · 2019-01-23T17:02:53Z

Pat Davitt answered · Jan 23, 2019 at 05:02 PM

You need to turn on the DVCC "Limit Charge Current" switch. A charge current settings box will then appear where you can enter a Max charge current for the system. That should set the max charge current for all the Victron devices that have that setting.

Below is an excerpt from the CCGX manual:

"A user-configurable maximum charge current setting. It works across the whole system. MPPTs
are automatically prioritized over the mains/generator. In case a CANBUS-BMS is connected and
the BMS requests a maximum charge current that is different from the user-configurable
setting, the lower of the two will be used. This setting is available in the “Settings → “System
Setup” menu on the Venus-device."

Pat

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ben ♦ commented · Jan 24, 2019 at 01:03 AM

Thanks for the suggestion. However, I never turned on the "Limit Charge Current" setting -- I simply enabled DVCC and the SVS. Somehow, it appears doing that managed to change the DC Limit on the Quattro, sending it back to its default value.

When I'm in a position to run a test, I'll try to repeat this behavior by toggling it again. It might be a bug.

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Pat Davitt ben ♦ commented · Jan 24, 2019 at 01:11 PM

Does all your device's firmware meet the minimums required for DVCC? List is below:

Required minimum firmware versions:
Multi/Quattro: 422
CCGX / Venus GX: v2.12
VE.Direct MPPTs: v1.29
VE.Can MPPT Solar Chargers cannot be used: they do not yet support the new control
mechanisms.
Lynx Ion + Shunt: v2.04
Lynx BMS: v1.09

Is so, it may be a bug. I would turn on the DVCC "Limit Charge Current" and set it to 200A. Then check your devices for their behavior . If everything looks good, why not leave it enabled? DVCC is designed to take over charging control of the entire system.

Pat

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ben ♦ Pat Davitt commented · Jan 24, 2019 at 05:04 PM

Yeah, all the firmware is up to date.

Good idea to try it and see what it does.

The reason I don't just turn it on is three-fold:

1) This is a production system: my home. I don't enable new features just for fun, because a mistake or a bug could leave me in a precarious situation. I don't even update firmware for fun, but in this case I wanted SVS.

2) The DCC feature is somewhat complex and poorly documented. I still cannot tell from the description how it works and what, exactly, it does. The wording is ambiguous, and right now I understand exactly how my chargers work. Flipping that switch would put me back in the fog.

[cont'd]

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ben ♦ Pat Davitt commented · Jan 24, 2019 at 05:04 PM

3) Even if I generously assign the most sophisticated, amazing DCC algorithm that I can imagine, I can't figure out what it will do for me. My chargers are voltage-governed. I have no BMS to transmit a charge limit request. My circuit is designed to accept the full current from all of my chargers. So, I suppose I can't figure out why I would use this feature? Maybe I'm missing something.

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