What’s going on with my voltage?

[Bluedog225]

I set up my panels about a month ago.

I’m charging the SOK rack with victron mppts, Cerbo GX. Quattro. All running a small air con.

I’ve been out of town for the last 30 days. System is working fine.

I wonder why my voltage profile changed so dramatically? It’s been on auto pilot.

Any ideas?

 

[sunshine_eggo]

I would assume they're engaging charge protection, and the BMS is cutting the batteries out of the charge circuit causing a voltage spike.

On days that it doesn't happen, either the imbalance is resolved and no longer present, or the granularity of the data is too coarse to see the spike.

What does VRM report with 1min logging intervals? You should be able to zoom in on a past day and get decent resolution.

 

[Bluedog225]

Same with other mppt

 

[sunshine_eggo]

If I'm right, it would affect all chargers active at the moment.

SOK closed loop with Cerbo?

VRM shows?

 

[Bluedog225]

I was up there briefly this morning and took a couple of shots. But not comprehensive.

I’ll get more later.

And thanks

 

[Bluedog225]

If I'm right, it would affect all chargers active at the moment.

SOK closed loop with Cerbo?

VRM shows?

I believe yes, SOK closed loop with Cerbo.

I don’t have VRM yet.

 

[sunshine_eggo]

I believe yes, SOK closed loop with Cerbo.

With closed loop, the BMS will send a signal to the Cerbo to limit charging to 0A, BUT the BMS can still trigger cut-off. This is more common with multiple batteries.

I don’t have VRM yet.

I am verklempt. I have no words.

 

[robby]

It almost looks like the kind of thing I would see with my system when that one Pesky EG4LL battery pack would lose balance on three cells. As soon as a load hit the whole pack voltage would dive then come back up to some high voltage number.
Have you checked the individual cell voltages?

 

[Bluedog225]

It almost looks like the kind of thing I would see with my system when that one Pesky EG4LL battery pack would lose balance on three cells. As soon as a load hit the whole pack voltage would dive then come back up to some high voltage number.
Have you checked the individual cell voltages?

I have not checked. Now that I’m back in state I will dig in. I’m in houston for a few days but after I will spend a morning out there.

 

[400bird]

Is it just that the weather is hotter and your panels are making a little less power? Or using more? Thus you're just not fully charging.

The graphs don't quite show anything limiting solar production to back up the BMS doing something.

 

[wpns]

Your battery voltage scale keeps jumping all over the place, can you scale it to approximately zero and 100%?

 

[Bluedog225]

I don’t yet know how to adjust the voltage scale. I got some more readings this morning. 3 time intervals for each of the mppts.

It’s a distinct phenomena. I have charged nothing.

 

[ricardocello]

Eggo said it earlier. Your SOK batteries are probably disconnecting due to over voltage of a cell, caused by imbalance.
Since you don't have a shunt, you can't tell what the battery current is during the high voltage spikes (56.8V?), but I'm guessing it is 0.
Because the BMS said "I can't take any more".

 

[Bluedog225]

That makes sense. I wanted to provide more data points.

And I do have a shunt. It’s no help. Ordered last week. It’s sitting here in my kitchen table.

 

[Bluedog225]

Though why unbalanced for so long?

 

[ricardocello]

Though why unbalanced for so long?

On the Cerbo, if you are closed loop with the SOK rack, you should see it as a device in the console menu.
Under Details >, do you see something like this?
(Edit: These are my EG4-LLs, need to determine if the SOKs provide this info).


Just before the voltage jumps, if you can watch this screen, you’ll see the lowest/highest cell voltage start to separate.
Also check to see if it blocks charging.
You may be able to catch it in the act, so to speak.

Not having VRM makes this challenging, I assume there is no internet.

 

[Bluedog225]

Yep. No internet. Working on that next.

I’ll check for that screen.

Thanks!

 

[sunshine_eggo]

On the Cerbo, if you are closed loop with the SOK rack, you should see it as a device in the console menu.
Under Details >, do you see something like this?
View attachment 228539

Just before the voltage jumps, if you can watch this screen, you’ll see the lowest/highest cell voltage start to separate.
Also check to see if it blocks charging.
You may be able to catch it in the act, so to speak.

Not having VRM makes this challenging, I assume there is no internet.

I'm glad to the the SOK report min/max values. I was disappointed this information is NOT available with the Trophy 304Ah BMS. No cell data is passed through to the GX.

 

[ricardocello]

I'm glad to the the SOK report min/max values

That menu wasn't the SOK, that was my screen for the EG4-LLs I have.
I was asking Bluedog if he has a similar screen on his system. Updated post for clarification.

 

[sunshine_eggo]

That menu wasn't the SOK, that was my screen for the EG4-LLs I have.
I was asking Bluedog if he has a similar screen on his system. Updated post for clarification.

I thought all those units used some variant of the Pace BMS as they all run off the Pylontech driver, and I would expect the same data to be passed through.

What version of Venus OS are you running?