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mbelgil avatar image
mbelgil asked

Inherited off-grid legacy Victron system but Venus GX doesn't fully control

Hi all,

I've recently moved into an off-grid home with a Victron solar power system and large backup generator (totally new to all this!). Currently the system has various rules that enable the generator to kick-in at certain times, e.g. when the house Watts exceed 1500 for 10secs or when the battery power drops below a certain percentage, etc.

I have a Venus GX that enables me to monitor everything, but currently it does not allow me to make any changes to the relay rules in place at the moment - I've been told that these rules are setup in one of the two Inverters in the system (which I cannot change because I don't have a dongle for my laptop). I also cannot control my generator remotely.

My question for those experts out there is: how do I modify my system so that everything can be controlled within the Venus GX (remotely)? I've attached some photos showing my system configuration. Do I need to add anything additional to this? Does the GX need to be connected in a different way?

Any help very much appreciated!

Michael.


Venus GX - VGX
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3 Answers
JohnC avatar image
JohnC answered ·

Hi @mbelgil

You have quite a complex system there. General observations..

1. Your first pic is of an older Phoenix (the red bird), and isn't compatible with the Venus. That'll be why it's not connected. But it seems to be for 'special use', as it only feeds to a twin ac outlet. You could leave it turned off, unless you actually use it. (maybe a water heater or somesuch?)

2. The second pic is your main system, and by the notations on the boxes, a BMV is being used to switch your genny, and not the inverter. There's several ways to switch the genny, but the clues from the pic lead to the BMV. Even zooming in I can't quite read the model, but maybe covered here: https://www.victronenergy.com/upload/documents/Manual-BMV-700-700H-702-712-EN-NL-FR-DE-ES-SE.pdf

3. Your Venus GX has an ethernet cable heading off somewhere, hopefully to a router. With some web, and signed in to VRM portal, you'll have great monitoring and remote access (from even the other side of the world) to much of your kit's settings. Inverter settings via 'Remote VEConfigure', no dongle necessary..

4. 3rd pic suggests a BT link to the GX, but that might also be available via wifi or ethernet LAN. (or VRM WAN).

There's some capability (or potentially) there in your system already. You'll need to explore it to get the best from it. Have fun, and come back as you need..

PS. That Trace pwm solar cc is your 'weakness'. A blue mppt would look better (and communicate).. :)

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mbelgil avatar image
mbelgil answered ·

Hi @JohnC,

Thanks so much for the quick response! You're right about the first inverter: its only feeding the main water pump for the house. (I guess that's so that its not included in 1500 watt rule, and can be used freely).

You're also right about the ethernet connection and I am able to log in remotely and monitor everything online - see images attached showing some settings from the Remote Console. By the look of these, I may actually be able to control the BMV and the Inverter relay settings...(?)

I did a quick search for 'Remote VEConfigure' and the option to do this seems missing from the online portal page (see screenshot - should there be some extra settings at the bottom of the page here?).

I've also attached some images of the generator setup - do you know if there's anything I need to add to be able to start/stop this manually from the Remote Console (currently doesn't work).

Much appreciated!

Michael.


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JohnC avatar image JohnC ♦ commented ·

More randoms..

Yeh, your extra inverter on a household water pump is good. They can spike the power quite a bit, and having it off the main system would make things more livable.

Good too you have the webz. If you're using VRM's Remote Console, it can be slow if you're far from the server. If you have LAN access, just type "venus.local" into a browser tab and you'll get fast local response. One at a time though, and the one you're using will push the other off.

'Remote VEConfigure' on VRM should show directly below the stuff in your Device List screenshot. Can you not scroll to it? Try another browser if not.

Your genny autostart may not be the one you think it is. Might even have been changed over time on your setup. Lookee here for some basic options (one of which will apply to you): https://www.victronenergy.com/live/auto-generator-start-stop:start

Just gotta find the right button to press, hey.. :)

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mbelgil avatar image mbelgil JohnC ♦ commented ·

Hi @JohnC, thanks again for the tips - will do some further rummaging and return when the head scratching gets too much!

Cheers,

Michael.

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mbelgil avatar image
mbelgil answered ·

Ok, here's an update on this: from what I've gathered it seems that the Inverter and BMV both have independent rules that control relays to start/stop the generator.

I've successfully logged into the Inverter settings (see attached) and can see that there is a rule for the maximum wattage, and a rule for voltage - both of which can cause the generator to start/stop. On that, I've set the wattage ceiling to 2500 and the voltage floor to 21.5V.

On the BMV, there is also a setting for the battery SOC level so that the generator comes on if the battery is below a certain level, which I've also set to 65%. (There's also a voltage trigger too - now also set to 21.5V).

The problem is that despite being able to change these rules I'm still experiencing unexpected behaviour from the generator - each day this week it has come on, when the battery has been at around 80% - never lower than 75%. The voltage hasn't gone below 22V, and the wattage hasn't spiked above 1500W either.

On the VenusGX Remote Console there are also a set of conditions for triggering generator start/stop (attached again). It seems that these rules are also being ignored.

I guess my question is: am I missing something? Is there anything else that can trigger the generator to go off? (The weather here has been quite dull and rainy, so the batteries are definitely not charging as they should, if that makes a difference).



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JohnC avatar image JohnC ♦ commented ·

Perhaps the only way to know for sure is to trace the genny wiring back to the item controlling it. Maybe unusual (but not impossible) to have more than one start/stop mechanism doing this.

I actually hope in your case it's not the BMV, which I suspect isn't set up correctly, overestimating SOC, and possibly allowing your batts to spend too much time at low V. You haven't said what they are, but if pb's then I wouldn't be happy seeing them below 25.3V, unless under load. Down below 23V for much time would send me into panic mode. SOC is a calculated figure, and you get a say in how it's calculated.

But it's impossible to diagnose fully remotely. Maybe we can help more if you posted VRM graphs of your Vbat, charge & load. Perhaps in another question once you get past this one.

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mbelgil avatar image mbelgil JohnC ♦ commented ·

Hi @JohnC,

Thanks for responding again - much appreciated. I've now established the the BMV is most likely the trigger, as you suspected. (Batteries are pBs too).

See attached image of all the settings currently in the BMV. I changed the relay mode from CHRG to REM, and since then the battery has discharged below 75% without any relay being triggered. So hopefully now this can be controlled just by the Remote Console...

The other thing I (foolishly) tried was to synchronise the BMV, but this has now caused the SOC to jump to 100% (it was 74%). If I leave this, will it sort itself out, or will I need to resynchronise when I estimate the batteries are full? (Slightly scary!).

(Also attached are some graphs from past hour, if that helps).

Thanks,

Michael.

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JohnC avatar image JohnC ♦ mbelgil commented ·

@mbelgil

Yeh the graphs help. They suggest to me your batts aren't at a critical stage, but they're far from being fully charged.

Best not to sync the bmv until you know the batts are fully charged (scary or no), and if you look in the bmv settings you posted there's the settings that will do it automagically. Notably 'Charged voltage 26.4V' and the 'Tail Current 4%'.

Now I think they're a little loose, and perhaps syncing too often. For me, a CV of 27.4V and a tail of 2% would be more realistic. I could even get away with perhaps 1%. Every 1% for you means 4.5A, and if your charge is lower than the Tail and still holding above CV for 3min, it will sync.

One of the reasons I love VRM graphs so much is that you can extrapolate the Tail A curve off into where you can imagine it flat, and that's the perfect place to sync. But it's not a perfect world, and you should sync regularly, so compromise then to a practical level.

Hope this makes sense. And having said all that, I don't rely on SOC myself, and much prefer to start/stop my genny manually. I know my pb's, but if I had Li's that might change.. :)

Bedtime reading: https://www.victronenergy.com/upload/documents/Manual-BMV-700-700H-702-712-EN-NL-FR-DE-ES-SE.pdf



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mbelgil avatar image mbelgil JohnC ♦ commented ·

Hi @JohnC,

Thanks again for the tips - I'll have a look at tightening up the BMV settings for the syncing I reckon.

I guess my main question is: aside from the BMV, how do I know when the batteries are fully charged? Are there other ways to tell? (The charge controller maybe?).

Cheers,

Michael.

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