Inverted current values in Multiplus-II

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Ivar Wagle asked Dec 20, '21

Inverted current values in Multiplus-II

Dear friends,

I am seeing some strange values while charging from grenerator in an offgrid cabin.

System setup:

- REC Q BMS
- 16 Winston Lifepo 300 Ah cells connected in series@48V
- Multiplus-II 48/5000/70-50
- CerboGX (fw. v. 2.73)
- Smart Solar MPPT 250/85
Generator: Honda EU70is

The Multi was installed prevously this year, but were after a while replaced by the dealer with a new unit due to malfunction (constant humming/buzzing sound, even with no load).

Upon installing the replacement, I allso installed a surge protection between the genset and the Multi. The AC-Out L1 leads to a breaker box with overload protection and 4 RDCs. They are all connected to ground. The genset is alsoo tied to ground with another ground ple connected to the chassie.

I am not sur exactely in the installation the fault appeard, but while charging from the genset, the Multiplus AC-In L1 shows negative current (A) and watt (slightly). The AC-Out L1 shows high negative values (-4100W / -18.1A).

However, the BMS menue on the Cerbo shows that the batteries are charging at full power.

On the Pages display the Generator icon shows a slight negative value (around 100W), that the Muti is in bulk mode and that current is flowing into the battery bank. See the attached screen shots.

Can anyone help med make sence of this or sugest where to start the troubleshooting? Preferabliy, suggest a solution?

Multiplus-II battery charging Generator

001-values-from-multiplusjpg.jpg (113.2 KiB)

002-values-from-recbms-charging.jpg (109.5 KiB)

003-pages-showing-negative-production-from-genset.jpg (140.8 KiB)

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Ivar Wagle answered · Jan 15, 2022 at 01:03 AM

In case you are experience the same issue, my excellent dealer, Farco, had the solution within 30 seconds on the phone.

It seems that some devices have an issue with the 3,5mm jack socet on the bottom. The 3,5mm socket is for hooking up the Victron's AC Current Tansofrmer for Multiplus II. On the affected devices, a short-circuit makes the readings charge power flows become inverted. On

The short and sweet solution is to poke an ordinary random 3,5mm plug (your old headset) several times in and out. This apparently bends the springs and contact back to -un-short it.

It immediately fixed the values.

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hacky commented · May 30, 2023 at 01:50 PM

Thanks for this explanation.

I had the same problem after pulling the sensor once for changing some wires, even though the system was working perfectly, before.

Now pulling the plug out, brings the system back to normal opperation, but your "repair" does not work for me. Anytime, I put the plug back, the system runs in the wrong direction. Can anyone give some more info here?

I mean, it is probably easy to find a workarount to switch off the relays for OUT 2 and grid upon grid failiure, but I would prefer the original solution.

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astoria36mq commented · Oct 12, 2023 at 10:30 PM

Thank you! Multiplus II 2x120 bought August 23 was working fine until about a week ago when the display of AC in and AC out started showing negative amperage. Your fix worked like a charm for me. Display is back to normal.

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Modifications Space

Node Red Space

Answer 1 · 2021-12-20T21:29:00Z

Rob Duthie answered · Dec 20, 2021 at 09:29 PM

Hi

Is the Genset AC input transposed?

Need to see all the setting for the Cerbo controller?

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Ivar Wagle commented · Dec 21, 2021 at 01:20 AM

Thank you for replying.

I´m afraid you need to elaborate.

What does it mean that the Genset AC input is transposed?

Thera are alot of settings in the Cerbo. Could you be a litle more specific on the settings we need to expose?

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Rob Duthie Ivar Wagle commented · Dec 21, 2021 at 01:30 AM

The phase and neutral are swapped over.

Re the Cerbo you need to print out all the set points you can do this via the VRM site

As per sample attached.

Cerbo sample print out.txt

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cerbo-sample-print-out.txt (3.1 KiB)

Ivar Wagle Rob Duthie commented · Dec 30, 2021 at 09:57 PM

Thanks again, and apologies for late respons.

I have been to find the option of downloading the Cerbo's setpoints on VRM. Have been google it as well. Is it the MultiPlus settings I need to download, eg. download the ve.configure file for the Muti?

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