It should close its contacts when SOC is lower than 10% and it should open the contacts when SOC is higher than 40%.
It seems to be very easy but in my system the relay 1 doesn’t work at all – it doesn’t show any reaction be the SOC as it may…
What I configured is the following:
1st step:Settings → Relay → Function Relay 1 → Generator start/stop (see image 1)
2nd step:
Settings → Generator start/stop → auto start functionality → (shift the slider in position „on“) (see image 2)
3rd step:
Settings → Generator start/stop → Settings (generator start/stop) → Conditions → Battery SOC enabled → Use battery SOC value to start/stop → start when battery SOC is lower than 10% → stop when battery SOC is higher than 40% (see image 3)
4th step:
Settings → General → reboot
The relay 1 does not work …. - did I forget something?
I would be very thankful for any help in this issue.
Config seems to be correct.
What happens if you trigger a manual “generator start”?
Does the relay respond to that?
If you don’t hear the relay “click”, you might have a broken relay.
If it clicks but no action is triggered, you might have a fault in your wiring to the relay.
By the way: if you’re using the same percentages for normal hours as quiet hours, you can just disable that feature altogether.
Edit: some hardware & software info of your system would be very useful.
On what kind of GX device are you running which Venus OS version ?
Dear Bart Champagne,
thank you very much for your quick response!
The idea to try with manual “generator start” is very good. Because the installation is situated in a partner school in Tanzania (myself I’m in Germany) I will contact my colleague there and tell him this news. He will try this feature and I’ll give feedback soon.
…“if you’re using the same percentages for normal hours as quiet hours, you can just disable that feature altogether” - how can I do this? Could you explain me, please?
A bit more in detail about our system: It was installed in 2023. It is a 5 kW-solar installation, only AC-coupled. No use of any MPPT. The PV-inverter is from SMA, it is a “Sunny Mini Central 5000A”. The battery inverter is Victron Multiplus II, 48V-5000, separately connected to a Cerbo GX. The battery system is from WECO (Italy), it performs well with Victron, 3 batteries from the WECO-type 5k3, all together 15,9 kWh capacity. That’s all - a pretty simple system.
We would like so much to trigger the relay 1 depending on SOC in order to give support when the batteries are down. (But in reality, we don’t have a “true” generator - our “generator” is the Tanzanian grid.) Therefore we already installed a contactor and wired it correctly with the Relay 1 of the Cerbo. Before installing that I made sure that the coil of the contactor does need too much current with regard to the current carrying capacity for relay 1. Everything is working correctly so far: If we bridge the 2 cables for relay 1 manually then the contactor attracts and connects the Multiplus with TANESCO (Tanzanian grid). But up to now we were not able to configure the Cerbo so that this runs automatically… We tried to do everything - it was in vain. But it must being said that we are new with Victron.
Hope to hear from you again. Thank you very much.
You say that you used the relay in the Cerbo to drive a contactor, bit did you consider the surge voltages and make sure you had a contactor with protective diodes to prevent Cerbo relay damage. You should tell your colleague to set Relay 1 to manual operation, disconnect the contactor then test for resistance on the NO and common terminals when the relay is on and off to make sure it is working. You may have damaged the switch part of the relay, many people have done this when driving a contactor without using a proper contactor or adding extra diode.
Another solution to your problem could be to always stay grid connected and configure ESS.
Set a very low grid setpoint (50W), enable “Optimized with Batterylife” mode and set minimum SoC to 10-20%.
That way the system will use as much from the batteries as possible and when they’re empty the system will automagically start taking power from the grid.
This will require reconfiguration of the Multi but that can be done remotely.
You could also program the Multi to “Ignore AC In” depending on the state of an input contact.
The Multi input contact can be wired to a GX relay that is driven by the generator function you’re already trying to use.
The added advantage of this option is that you’re not driving a large relay with the small GX relay so there’s no risk of burning the GX relay, as @pwfarnell already pointed out.
Edit: all depends of course on the GX actually knowing the SoC of your batteries.
With Lithium batteries the SoC can not be determined reliably by the battery voltage, so the internal battery monitor of the Multi doesn’t really work.
In case this isn’t already done: you need to connect the batteries to the GX CAN port at 500kBits/s.
They’re not officially supported but should work just fine.
Dear pwfarnell,
thank you very much for your comments. Indeed, I wasn’t aware of the surge voltage problem with contactors BUT just I looked on the spcifications of the installed contactor. It is an ABB 16-30-01-11 type, 20-60V DC and it is written in the datasheet that it HAS surge protection. Therefore I guess that I (hopefully) couldn’t have damaged the relay 1 …
I think it will be best that my Tanzanian colleague tries to test for resistance on the NO and common terminals when the relay is on and off.
Just I looked on the Victron’s menu. Is it correct if we configure like that:
settings - generator start/stop - manual start - start generator ?
If yes, I have an additional question (therefore I added the picture from the last settings-display): Isn’t it necessary that we additionally configure the 2nd line with: “run for (hh:mm)” - so to put in an arbitrary value for the time intervall? Otherwise the relay 1 wouldn’t operate, that’s correct?
And after doing that the relay 1 should shut through immediately ?
Thank you and greetings
Thank you pwfarnell and Bart Champagne for further explications!
I’ll firstly start by the manually operating of the generator start/stop as soon as possible. From my remote place I tried this earlier without success, but I’ll now instruct my colleague in Tanzania that he does it directly staying beside the devices and check the potential answer of the relay 1.
@Bart Champagne: For your different alternatives I have some more questions which we mustn’t answer all at this time but the one is: If I use the ESS configuration, can I be sure that the system will not feed back power into the Tanzanian grid?
It is strictly forbidden in this country and I was being told that in the case you do that and they check it somehow there will be financial punishments.
And about your remark that the true SOC is really transferred from the BMS to the GX (and not determined by measurings within the Multiplus) - yes, it’s for sure correctly because the WECO batteries are being displayed as devices in the Cerbo GX, including the SOC.
Greetings to you both
If it’s not and grid feedback is absolutely forbidden, the “Ignore AC in” option is probably better than the ESS option.
The Multiplus-II already has 2 relays between the grid and itself so there’s no real need to add another external one.
Since you already have the external relay it doesn’t make much difference, except the amount of power that’s switched by the GX relay.
By the way: you should configure the “PV inverter support” assistant in the Multiplus, so it can regulate the SMA inverter with frequency shifting.
Otherwise you’re going to damage your batteries.
If you’re not using different conditions based on the hour (the “quiet hours” option), you can disable that in the settings.
Hi Bart Champagne,
the SMA PV-inverter is not visible in the Cerbo’s display. The SMA and the Cerbo don’t communicate together.
The “PV inverter support” assistant in the Multiplus is configured and regulates the SMA inverter with frequency shifting.
But, by the way, as you touch this point, I am not very satisfied with this management of FSPC:
It seems to me that the Multiplus starts rising up its frequency too early, already when the SOC is in the middle (50-60%). My impression is that this is too early - it would be better if FSPC starts around 80% or even higher.
In the PV-inverter I made the following settings:
FSPC starts at 51 Hz
FSPC downregulates the power of the inverter to zero at 52 Hz
FSPC switches off the PV-inverter at 54,5 Hz
(According to the SMA description the derating between 51 Hz and 52 Hz should work linearly.)
And in the configuration of the assistant in the Multiplus I set the same (see picture)
.
But oftenly I see the frequency of the system at 51,xx Hz although the SOC only is in the middle…
Perhaps you can say me something about this phenomenon?
Good morning to everybody,
just I got the results fresh from Tanzania:
Yes, the relay clicks when it is being triggered manually! The noise is very clear! Interesting for me…
That means we have to look for the mistake somewhere within the configuration, isn’t it?
I am very interesting about any ideas from your side how we can search about the mistake further in detail.
Thank you very much in advance!
Dear @Bart Champagne and dear @pwfarnell,
good news from Tanzania:
After cabling the relay with the Cerbo it runs well with the grid (as generator) as soon as it was triggered manually from the Cerbo. No problem.
BUT - … the remaining question now is: Why doesn’t it start automatically?
Do you have any idea what we can do furthermore?
Shall we make a firmware-update for the Cerbo? I was unsure if this is a good idea.
I guess, before updating the firmware it shoud be advantageous to make a backup of the old one, isn’t it?
Could you please give me an advice how to execute the backup?
Thank you and greetings
I am out of ideas re the generator settings, at least you have confirmed it is not a hardware issue.
Firmware updates are covered in Section 9 of the manual. The Cerbo operates 2 separate areas of the file system, one with current firmware, one with the previous version. When you update, the new version overwrites the previous version and reboots from the new version. The current version then becomes the previous version. You can then always reboot back of there are problems.
guystewart
(Guy Stewart (Victron Community Manager))
18
Try changing the “start after condition time” to 30 seconds.
You currently have it set to 0 seconds
Also, you have the low SOC threshold at 10%, this means that the relay won’t activate at 10%, but at 9%, maybe that is already obvious but worth mentioning to be sure)
Hi @guystewart and @pwfarnell,
again interesting news from your side!
Today we managed to change the settings “start after condition time” to 30 seconds and additionally the lower value for SOC to 8%.
Now we wait until tomorrow and see what happens…
If things won’t be okay we try with a firmware update.
In any case I will let you know what came out.
Thank you for your committment for us.
Unless you are running a really old (beta) version I doubt that your problem will be in the software.
The generator start functions are very well tested and are bug free in the Stable software release.
A start SoC of 8 or 10% is too low in my book.
If you allow the batteries to run that low you risk damaging them.
You also risk that the batteries disconnect their output, shutting down the GX and the power source to the grid relay*.
I wouldn’t go much lower than 20-30%.
If you want to test the grid relay function, just set the “Start” SoC to 1 or 2% lower than the current SoC (and the “Stop” SoC at 10% higher orso), then wait a few minutes.
If that test is successful you can always change the settings to Start at 25% and Stop at 45%.
* : This morning I had to do a dark site recovery because the batteries at an off-grid site ran empty & shut down during a runtime calibration test, everything went offline just before the sun came up.
Batteries shut down → Victron inverters down → no microgrid → PV inverters couldn’t start up → deadlock.
Had to hook up a generator to start up the Multi’s so the PV inverters could start up.
It was nearby so not a big issue, but still annoying
There is an MPPT onsite to prevent exactly this from happening, I just haven’t found the time to hook it up yet.
