Questions on warm-up and cooldown

Modifications
1

v3.65~3 It appears the generator cool down does not function as described . The state changes to cool down, but the charger still pulls current as the engine stops. Not sure about warm up, my transfer switch delay masks any warm-up issue.

I noticed the charger doesn’t honor the Prefer Renewable Energy setting from node red while on generator like it does on shore power. Also the symbol on the charger indicates generator, shore power card still shows the shore symbol. I do have the serial battery driver mod.

2

The cool down only works if your AC Input is configured as Generator.
Since you mention a change over switch, I’m assuming you have a Multi that connects either to the grid or to a generator and your AC Input is configured as Grid.
And then the cool down function doesn’t work.
This is older, standard and documented behavior, very unlikely that this is related to this beta release.

What you can do is create a Node Red flow to switch your AC Input from Grid to Generator.
Either use the Generator start/stop state or a dry contact on your transfer switch wired to a Digital Input.
Best practice is to configure a Digital Input, that gets switched on if the generator is actually running, as Generator, so the GX knows the actual state and not what the state should be.

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3

Thanks Bart, the Cerbo Generator start/stop documentation makes no mention of adding node red or having the AC input set to generator.
Yes a transfer switch does the changeover from shore to genset. I do have a 3 wire interface for start/stop and gpio input 4 set as generator, tied to the status output of the generator. Although now I’m not certain what the status feedback is used for.

My AC input is set as shore power. I just assumed the Cerbo would change what’s needed to operate on generator since it’s the device starting the generator and it has feedback on the running status of the generator and already controls the Multiplus. The battery card appears to know it’s charging from a generator, the shore/grid card doesn’t, and the inverter must have a clue since it ignores the charge from solar only request.

Yes I know it’s not a beta issue, I also tested it on this 3.65 semi-release version in case this isn’t the way it should work.

Is there other documentation on how the Cerbo genset start/stop feature should operate?

4

The manual is always a good start: 18. GX - Generator auto start/stop
As for Node Red: that’s not a core functionality of VenusOS so documentation is limited.
It would also be impossible to list all the possible options of Node Red.

If you’re switching between Shore and Generator on your AC Input, the values to push to the AC input Source node would be 3 and 2 (grid is 1).

A Digital Input configured as Generator will use the state of that input to determine the actual state of the generator.
Without this input, the state of the generator on the GX will correspond to the state of the relay used to start the generator.
If the relay is set to start the generator but in reality the generator hasn’t started (ran out of fuel, not connected, …), the digital input will signal this.
This is also mentioned in the manual by the way.

As a rule of thumb: be careful when making assumptions.
Assumptions are the mother of all fsckups :grin:

5

Thanks Bart, that’s the docs I used to set up my system but I still don’t see any mention of setting the AC input to generator to get this feature to fully operate.

I don’t believe that’s correct. My Cerbo doesn’t use that input to determine state at all. It will switch to warmup, then run, even if the generator fails to start. And it will switch to cool down, and stop, even if the generator is still running. As far as I can tell, it’s used for tracking run time. I’m fairly confident I can whip up a workaround using node red, but I wanted to verify it wasn’t my setup issue before I reinvented a feature that already exists.

And that’s exactly the way I expected the state machine to work, but I doesn’t. Maybe you assumed they meant the digital input provides that visible state, but that’s not what it says.

18.12. Generator state and improved operating hours via a digital input

For accurate engine status and improved tracking of accumulated operating hours on the GX device, an additional dry-contact signal wire can be used.

To enable this feature, go to Settings → I/O → Digital Inputs and configure the respective input as “Generator”.

Once configured, the generator state will be visible in the Device list, and the total run time will be determined based on the state of this digital input.

Indeed, but you have to start someplace when the docs implied that it should operate a certain way. All I’m trying to figure out if it’s a software bug that someone should know about, an issue with my setup, or that’s just the way it’s intended to operate.

6

Hi Paul,

I’ve moved your question to the modifications category, as this is not related to v3.65, or a regression compared to v3.64. Or did this work better for you in v3.64? I can’t think why anything would have changed:

Nothing changed with regards to warmup & cooldown, and also not a single line of other code related to multis, quattros, or generators, between v3.64 and v3.65.

1 Like
7

I would need to recreate the setup and test to be 100% sure but my generator hasn’t been connected in over a year so my memory is a bit foggy on the subject.
My previous reply was at 3AM local time so that didn’t help on the foggyness either :slight_smile:

Maybe you’re right about the digital input being more an hour counter than a state indicator.
In the generator menu there’s also an option to trigger an alarm if no AC input is detected, that’s probably not a bad thing either.
The Start/Stop conditions have an option to stop the generator when AC input is detected but that’s only useful if you have a Quattro with dedicated Genset AC in, otherwise the AC in from the generator would trigger it to shut down because it sees itself :slight_smile:

My generator has a DSE controller that handles the warm-up & cooldown by signaling a relay to connect loads after warm-up and disconnect them during cooldown.
At some point I reprogrammed it to bypass all that and have the GX handle those sequences but as stated, I should recheck and retest all that to be sure.

What I am sure of is that the AC In should be set to Generator for it all to function properly.
And because I have/had some single AC In Multis with a transfer switch, I remember having looked up on how to change the Input type based on certain conditions.
And since Node Red is embedded in my GX, that was the easiest option.

8

Thanks Matthijs, I didn’t have the generator set up for testing until recently but it’s never performed a cool down cycle on any of the 3.70 beta versions or this recent v3.65.

Can you confirm the warm up & cool down states should work without node red intervention or changing the AC input to generator when using the 3 wire connection and generator status input? The documentation reads that way, but I’m not sure the Cerbo actually does it. I was searching the forum last night, seems there is at least one other person that has the same issue with an RV set up similar to mine.

9

Thanks Bart, it would be interesting to see if your genset behaves properly. I’ll probably need to implement some sort of cool down, my generator hates the load during shutdown, it’s very hard to start after that.

I can’t imagine Victron would implement a feature that requires a customer code workaround to operate properly. It does sound like I have something set wrong, or a code issue someplace.

10

What you can always try is to set your AC In to ‘Generator’ (in System Setup) manually.
I am not familiar with the coding behind it or the evolution of additional features that use this input type but from what I can see the main goal of this input type is to properly measure how much you’re consuming from which energy source.
If the input type is set to Generator, even when you’re connected to shore power, your system won’t stop functioning.
From the top of my head the most annoying bits will be the consumption stats per input type that will be off.
But that way you can test if the generator cooldown sequence is handled properly if the input type is set to Generator.
The sequence should be:

  1. disconnect AC In from source
  2. allow generator to cool down without load
  3. shut down generator

Later on you can still decide if you want to automate the AC Input type or not.

How I see it, the system needs to know the exact input type (grid, generator, shore) to apply a few small extra features (such as cooldown) that were added to the code later in development.
The system can’t guess the correct input type as some people use the generator start/stop feature to dynamically connect to the grid or not - and the grid doesn’t require a cooldown :slight_smile:

Is it annoying that you need to create some custom (Node Red) logic if you want the input source to automagically update to the correct type based on specific conditions ?
Kind of, yes.
Then again, the more features are added to VenusOS and the more sophisticated it gets, it -unfortunately- becomes more and more a professional’s job to install and configure it.
Unless you work with GX systems on a very regular basis, it will be difficult to keep up with the features and underlying parameters that “you just have to know” to make it work to its full capabilities.

11

Thanks Bart, I’m not complaining about the implementation. I just want to know if that’s just how it is, I have something set wrong, or they have a Venus bug.

I fully understand this is beta, and a very complicated set of systems that need to play well together. I do find the docs a bit vague and often wrong, but if that’s the cost of having fast cycle times I can live with it.

On generator it ignores the “use solar only" and charges the battery hard, so I’m a bit hesitant to staticly change the input over.

It’s flexible enough, I’m sure I can get something to work.

12

I’m not familiar with your setup so it’s hard to comment on the details.
But you can be pretty sure that there are no bugs in the Generator Start/Stop code :slight_smile:
What do you mean by the “use solar only” parameter ?

13

Class A coach, single 24V Multiplus 2x120, inverter genset, intelligent transfer switch, DIY communicating battery, solar.

Said by no code guy…ever. It appears I’m not the only person with this issue. This is a very similar setup to mine that behaves the same way as mine, and not as the docs say it should behave.

The solar and wind priority function, using VE.Bus System control: Renewable energy preferred vs. Renewable energy not preferred. My system ignores the request while on generator and continues to charge the battery. On shore I have it set to limit charge to around 30% SOC by keeping the voltage at a lower setpoint. It’s been great for off-season storage. I could see this charge behavior being a “feature”, why else would you start a generator, but it seems it should listen to a request to back off. I have not tested the cool-down with an AC load AND the battery charger. It might drop the load but still keep the charger engaged, if that’s even possible.