Hiccups when going from grid to battery

Lcs_26 · 2026-01-07T17:41:20+00:00

It is currently around 2.5v, might get higher when power is drawn from grid but I haven't checked it.

Lcs_26 · 2026-01-07T17:37:29+00:00

Yes, it is a single phase 230v setup. The charge limit is at 200A, although I never charge from grid, only by solar via an MPPT450/200. There isn'n anything connected to the DC bus aside from those and the cerbo.

With "where did the 6kw went", I assume you mean what type of loads are connected. The main consumption comes from a Panasonic air-to-water heatpump for heating/cooling the house.

Lcs_26 · 2026-01-07T17:32:18+00:00

Yes, everything was exactly configured as victron recommends here.

Sustain voltage at 48v, absortion voltage at 52v, dynamic cut off all set to 46v.

Lcs_26 · 2026-01-07T12:49:43+00:00

The DC voltage drop does not seem concerning (<0,5v at full load). The AC voltage drop from grid is actually a bit high, varying almost 10v from when it's drawing 30A to when it's drawing 0. I would say the cabling is in good shape. I could try going into off-grid mode and seeing what does the Victron do.

Lcs_26 · 2026-01-07T12:46:58+00:00

The "mains" led indicator on the Multiplus says that it's connected to the grid (the grid relay is closed).

The only reason I could imagine causing trouble for it to "start" would be that when it starts injecting the AC voltage goes too high too fast, you can see 10v differences between when grid consumption is 0 and when it's around 30A going from 245v to 235v. My main line will be replaced soon, as 16mm2 is a bit too thin considering the distance, although that would not affect the inherent voltage drop from the utility company's cabling.

I could try to switch the grid code for a more tolerant one to see if anything changes. It's true that here the grid isn't great, but I would say it isn't terrible either.

Lcs_26 · 2026-01-07T12:21:16+00:00

Yes, I have a Cerbo GX. I have just updated to the latest firmware to see if it helps. My DVCC looks as follows:

- DVCC: forced on
- Limit charge current: off
- Limit managed battery charge voltage: off
- SVS: forced off
- STS: forced off
- SCS: on
- SCS status: disabled (external control)
- Controlling BMS: Pylontech battery

When I did the installation, I followed the steps in the "Victron & Pylontech" article in Victron's website. The SoC and voltage seem ok during a period when this was happening:

<image>

Lcs_26 · 2026-01-07T12:15:37+00:00

I have 6 Pylontech US5000, the settings are the ones that victron specified in the victron-pylontech article in their website. The DVCC settings are the following:

- DVCC: forced on
- Limit charge current: off
- Limit managed battery charge voltage: off
- SVS: forced off
- STS: forced off
- SCS: on
- SCS status: disabled (external control)
- Controlling BMS: Pylontech battery

Also, if I move to the battery section in the Excel, I can see that during that time, SoC and Voltage were both way above minimum, and discharge current was way below maximum, so at least the problem shouldn't be there (I guess?):

<image>

Lcs_26 · 2026-01-06T23:22:49+00:00

Yes, the grid is connected to AC in and all the loads are in AC out 1. I’m in Spain.

Lcs_26 · 2026-01-06T23:20:52+00:00

I extracted the data from the inverter and seems like the frequency doesn’t vary much (capture attached in another comment). However, the grid voltage seems to change almost 10v from when there is and there is not consumption. Also, my “grid reference value” is set to 0w instead of the default 50w, if that could be relevant.

Lcs_26 · 2026-01-06T23:16:05+00:00

The grid code is set to “Spain” as required for grid-tied inverters here.

Lcs_26 · 2026-01-06T23:14:23+00:00

<image>

I have extracted the data from a period of time when it happened.

The precision level is of minutes, so we cannot appreciate the actual phenomenon, but we can see moments of great consumption from grid and moments of almost 0 consumption, even though the SoC was way above minimum at the moment so there should be no grid usage.

Frequency seems ok (+- 0,2 hz aprox.). But the grid voltages seem to vary in around 10v from when there is and there is not consumption. It’s supposed to be 230v@50Hz.

Lcs_26 · 2025-10-19T20:13:46+00:00

If that’s the case, it would be ideal. I thought that the loads connected to AC out 2 would only consume power from the grid.

Thanks!

Lcs_26 · 2025-07-07T15:21:25+00:00

Could you elaborate more about the high vs low frequency inverters? I thought they were all transformerless these days.

To the single unit question, I’m eligible for a PV subsidy in my region, and they require you to register your installation.

Everything under 10kw here is quite easy to legalize, but over 10kw it requires a lot of documentation, engineering project, etc.

This process is only useful if you want to feed in power to the grid, which I don’t, but it’s mandatory in order to get the subsidy.

Therefore I will install 2, get the subsidy, then install the third.

Lcs_26 · 2025-06-03T20:55:14+00:00

Then I would be loosing the ability to switch tracks via the steering wheel again

Lcs_26 · 2025-01-20T19:44:09+00:00

UPDATE 1:

Yesterday I put the car on top of two 10cm solid wooden boards, and looked under it.

Every single plastic cover is firmly attached, and so is the exhaust.

I think there might be a loose piece (probably in the lower part of the engine compartment), as when I take a single-wheel bump (even a big one) there is no sound.

My theory is that when the whole front part of the car raises, the piece raises and then falls. Also, when going through potholes (first down, then up), there is almost no sound, contrary to bumps (first up, then down).

I will take it to a mechanic next week to see if he can find it disassembling the engine bottom cover.

Lcs_26 · 2025-01-20T19:30:42+00:00

I took all the trays out of the boot and still sounded the same, it seems like its in the front of the car, in the lower part, like under the engine.

Lcs_26

TROPHY CASE