N00b question - How to manually charge/discharge with a Node-Red flow

Node-RED
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Dear community members,

I’m a new user in the world of Victron equipment. I got my system running since half of november, and it’s doing great so far. The company which did the installation set it up to run in green mode, this results in the system doing nothing for days. I understand this is because the difference in buy and sell price is too small and it is the time of year sunshine is minimal.

This got me thinking: If the grid fails now, i’m stuck with a battery at minimum SoC. Also with little or no sun at all the battery is not being charged either.

So I started searching how to manually charge the battery a bit.

My system:

3-phase setup with 3 x multiplus 48/5000, Cerbo, MPPT 450/100 with 10 solar panels and 6 x Pylontech US5000c. Plenty of power and capacity to survive a possible grid failure for 3 – 4 days.

I also managed to connect a tablet with remote console so the family can see what is going on. I installed Venus OS large to get Node-Red running, and i’m able to SSH into the Cerbo.

After 2 weeks of uptime the system did a battery balancing and I had my first 30 kWh day (and 100% SoC). I tried to manually charge/discharge the battery by adjusting the Grid-Set-Point > little to no effect. To not disrupt the 28 day learning period I played around with adjusting the min SoC slider, this gave somewhat result to what I want. After a lot of googling and youtube, I still cannot find what I want (yet it is really simple).

So what am I looking for?

Real simple; a button/option/flow that lets me charge/discharge battery with x amount of amps/W (preferably with x amount of time or SoC).

I do want to have control over the power it’s going to push into the battery, right now the temperature of the battery is 2*C and I don’t think it’s a good idea to hammer it with 10 kWh.

Some members on this forum presented their ideas on AI to help them build a Node-Red flow. Good idea, I tried that as well and ChatGPT gave me a good output to work with. It came up with:

Inject node > function node (charge @ 3kWh) > Victron-output node

Right. Easy, but I’m stuck at the Victron Output node. Where is it? How do I talk to it and tell it what I want? Is Node-Red capable to do this? Am I missing something?

I’m aware of the 5 charge schedules which can be found on the control panel, but it’s missing the option of power control. And none of them give me the option to discharge. Node-Red is working correctly, I installed the dashboard and it presents some numbers and a gauge quite nicely.

So a little push in the right direction would be appreciated.

Thanx for reading, I’m learning as fast as I can :slight_smile:

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To answer your question. I am assuming you are running ESS? In that case to export you need to alter ESS grid set point to say -2000 to export 2kw. There are a few ways of doing that, but the most simple is the default Victron NodeRed nodes: The one you need is a Blue node with the bubble at the front “ESS Control”.

click on it and complete:

ESS = Venus Settings

Measurement = Grid Set Point (W).

leave others blank. Now get an inject node, change to number and inject -2000 every 5 secs or so. Join them up and click on inject. Another inject node of 0 would return you to zero.

1 Like
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Thanx David! Sorry for the late reply :face_with_peeking_eye:

I found the solution in a whole different way … If i open a browser and go to http // cerbo.local/gui-v2/ i get the console screen in my browser. In there i can easily control the GridSetPoint. But it doesn’t work. Took me a while to realize i had to turn of Dynamic-ESS and be able to (dis)charge the way i want.

And also now the scheduled charge works. Next week i will try NodeRED again to create a flow, i’ll let you know if i manage to succeed.

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Well David, thanx a lot. Just made a simple flow with inject to Venus settings and it works the way i wanted.

Really simple but hard to find how to accomplish this in NodeRed. Appreciated!

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@Knakkel

Try DESS again. It considers usage forecast, PV forecast and system efficiency, which is 80% for a round trip.

Try the following settings:

In VRM set min SOC (until grid failes) to a comfortable value, e.g 50%.

Leave BatteryLife on.

In VRM make setting for DESS
More/ Setting/ Dyn. ESS / System / Max (import/export) Power = 5kW

This setting will adjust the schedule in terms of maximum power pushed to or pull from grid, e.g. max grid set point.

Your 3 MP2 5K will together not use more than 5kW.

Check the restrictions. If restrict sell to grid is on, it will never set negative grid set point.

If this does not suite your needs or you like to tinker around than use NodeRed.

If grid fails, (D)ESS is switched off and MP2 uses remaining battery to serve you.
When grid comes back, (D)ESS is switched on automatically.

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@BjoernK

Hey Björn! Thanx for the instructions, these were actually the first things i tried to tinker with. Most of the time this doesn’t work because it’s on Dynamic. So all i could accomplish was to slide the min SoC slider around. Then still it would not charge because prices were to high, and discharging onto the grid did not happen at all. So (sometimes) i just want to take control a bit, and after that i turn on DESS again. I like the way DESS does its work, and mostly it does not need babysitting at all. I just needed to understand the why and how.

Anyway thanks for your input !

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If you like to understand DESS search for posts from dognose. He programmed parts of it and explained a lot.
With current beta there will be an improvement increasing SOC precision better than 1%, which caused some wired behavior.