question

maboth avatar image
maboth asked

Critical Load shows high values. How can I check the internal input current sensor of a MultiPlus II?

My critical load displays high values but there is no critical load connected. The result is that the System is very instable in ESS mode. It swaps between maximum load and maximum charge every seconds with no end. The input load on L1 displays 0W but the critical load displays hight values but there is nothing connected. I assume that the internal input current sensor might be defect.

It is right that the critical load is the difference between the output current (transformer) and the input current (AC in)? Because I saw a block diagram with the positions of two current sensors. There is no current sensor at AC out 1 to measure the critical load. So the Multi must calculate this load of the two current sensors.

How can I check the internal input current sensor?

input current
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5 Answers
marekp avatar image
marekp answered ·
3 comments
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maboth avatar image maboth commented ·

Looks like the same problem. But the bug is not fixed. I see no solution there. I know similar systems with Multis working. So there must be a bug in the software or defective hardware. Your answer is a good link to another question but not the solution or an answer for my question.

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marekp avatar image marekp maboth commented ·
Did you try the 3.5mm jack trick?

If you have CT sensor problem (ESS oscilating) the CT jack fault is most likely suspect.


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maboth avatar image maboth marekp commented ·
Thank you I didn't notice the solution because it was hidden in the comments. I put the solution as answer in this thread. Thank you very much.
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shaneyake avatar image
shaneyake answered ·

You can set ESS to External Control, this will put the inverter into passthrough.

You can then put a known load, like a kettle on the inverter output and see if it shows up on the input and output correctly, on the GX -> Menu -> Multiplus, it will show input and output values.

The multiplus only has 1 current sensor on the input, the output is a calculated value.
AC_INPUT + InverterPower = Load

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maboth avatar image maboth commented ·

Thank you very much. I do a test in passthrough mode, put a load on AC-out1. The current flows through the Multi and I see the additional load on the grid meter (EM24), but I don't see any current value AC-input on the remote console. Always 0W as AC-in current. My assumption that the input current sensor is defective seems to be correct. This makes the ESS control completely unstable. I wonder why the system itself has no self check for that.

Next week I will switch to an external current sensor and I will see.

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shaneyake avatar image shaneyake maboth commented ·
It is difficult to do a self check when you only have 1 sensor but yes. They could connect to grid and then charge battery at like 1kw for a few seconds and confirm reading is greater than 1kw so maybe one day.


Some people have had luck at just plugging in and out some headphones 10 times, most sensors faults are with the actually jack. Turn inverter off first tho.

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maboth avatar image maboth shaneyake commented ·
Thank you very much. That's incredible. After plugging my headphone 10 times in the 3.5mm jack as external current sensor, the internal current sensor starts to work. Great solution!!! Thank you. Thank you. Thank you.
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maboth avatar image
maboth answered ·

Thank you very much. That's incredible. After plugging my headphone 10 times in the 3.5mm jack as external current sensor, the internal current sensor starts to work. Great solution!!!

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Jason - UK avatar image
Jason - UK answered ·

@maboth Do you also have an external 100A Victron current sensor connected to the 3.5mm jack connection? I had a bit of a similar issue when I had my grid set point set to -10w & my external current sensor was fitted the wrong way round as I did not know it had a directional arrow at first.

If you do have one and are not using it, connect it to your meter tails plug it in and see what difference that makes.

The critical loads are just the loads connected to AC out1 as in the event of a supply failure to AC in1, only the loads connected to AC out1 are kept powered as ACout2 disconnects in the event of a failure of the supply to ACin1. Any data given for consumption is for both ACout1 and ACout2 as the current sensor is on the combined total output.

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maboth avatar image maboth commented ·
Next week I will have an external current sensor with 3.5mm jack (100A) and then I can try. I think the Multi calculates the critical load and displays me wrong results. But I don't know what are the basics of calculation. In inverter mode (ACin and ACout2 are disabled) the multi displays right values for critical load. So the reason must be find in ACin.
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maboth avatar image maboth commented ·

I see a different installation with the same configuration. In this installation the display shows the critical load right but not exactly. This is an indication that this number is only calculated. And if the input current sensor is defect (always 0W) then this calculated value is wrong and then the ESS system will over compensate this nonexistent load at AC out1.

I still missing an easy test for the input current sensor.

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popnic avatar image
popnic answered ·
@shaneyake @maboth @maboth and all Multiplus 2 owners and installers

Had same issue with AC In1 internal sensor solved using the suggested removal and plug in trick.

Somebody know what Victron has to say about it?

It is a bad connection in the 3.5 jack or it is something else?


I have serious doubts about the reliability of the system I working with and other similar system that I have in plan.

Thank you to for sharing your experience here and thank you for your support.

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Rob Duthie avatar image Rob Duthie commented ·

These 3.5mm jacks are a poor choice for CT connection due the very weak signals from the CTs anyway. They should have proper CT type connector or a terminal block like most other electrical controller with low signals.

The 3.5mm is for Audio gear!!!

Regards

Rob D

Electrical Engineer

NZ

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marekp avatar image marekp commented ·
There should be proper terminal connector and toggle switch for selecting internal or external CT.
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shaneyake avatar image shaneyake commented ·

Honestly 3.5mm jack is not a bad option for this kind of signal, in many ways the CT output is similar to an audio signal.

The problem comes in where you get some corrosion on the internal contacts. This seems to happen fairly often however we have actually only seen on 1 or 2 installs. So out of all the sites we have installed doesn't actually seem to be that common and can be quickly fixed with a 3.5mm jack. In my experience the multiplus-ii has been extremely reliable so wouldn't have any concerns there. I have had way more 250/100 fail than MP2.

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