question

corne avatar image
corne asked

AC output negative when grid connected

Hi guys

I have two sites with Victron multiplus II inverters.


When the grid is disconnected, the AC output is normal. As soon as the grid is connected the AC output becomes negative.

I completely disconnected all cables on the AC output and to only charge battery from grid and still AC output is negative.

screenshot-2022-07-24-121400.jpg

The inverter was on firmware 492 and updated to 497 and still issue is there.


Can you please help?


screenshot-2022-07-24-120433.jpgscreenshot-2022-07-24-120453.jpg

Multiplus-II
screenshot-2022-07-24-121400.jpg (54.6 KiB)
screenshot-2022-07-24-120453.jpg (26.7 KiB)
screenshot-2022-07-24-120433.jpg (27.2 KiB)
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wkirby avatar image wkirby ♦♦ commented ·
Very strange indeed.

Maybe a silly question, the grid is connected to AC-IN terminals and not the other AC-OUT terminals, just to clarify.

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3 Answers
corne avatar image
corne answered ·

Hi guys.


Any feedback?

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marekp avatar image marekp commented ·

@Corne

The question is, where is the energy coming from to charge the battery with 3476W when AC-in shows 0W.

Disconnect AC-out wires and tell us what happens.

Also make sure that grid is connected to AC-in. (see @WKirby question)

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corne avatar image corne marekp commented ·
Hi Mark.


On the first photo the AC-out wires are completely removed. Only AC input for charging batteries.


If AC -input is disconnected, then the AC-output is normal. If I connect AC-input with AC-out wires completely removed then it shows -3000W on AC-out.


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marekp avatar image marekp corne commented ·

@Corne

Did you make sure that grid is not connected to AC-out? If AC-out is disconnected how can the current go through AC-out?

What else do you have in your system?

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corne avatar image corne marekp commented ·
Yes 100%.


I hooked up another inverter with the same settings using the same wires and it worked perfectly.

Replace with the other inverter and it was faulty again. Did a complete settings reboot, downgraded firmware, changed grid. No luck same issue.


It is just a backup system with lithium battery. no ESS, no solar, no meter

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corne avatar image corne corne commented ·
I honestly do not know how the AC-out is negative with nothing connected to it. When I have a 4000W load connected and switch no grid, the ac-out drops to 2000W but same amps.


My supplier think its a mearing or shunt issue

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marekp avatar image marekp corne commented ·
@Corne

If the second unit was just dropped in without changing wiring and everything is normal, then the first unit needs to be replaced. Contact your distributor.

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corne avatar image corne marekp commented ·

Yes I agree with you. Thanks for the support.

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Frank avatar image
Frank answered ·

Hi, I have exactly the same problem with a Multiplus !! 48/5000. Have you had feedback from the distributor what the problem was ? Thanks

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sloanebiking avatar image
sloanebiking answered ·

There is a headphone type jack on these MP's that may be stuck, plug in a headphone plug into that jack and it may clear this problem, sounds crazy but it fixed a similar problem on mine. There is an article about this issue, I don't remember if it should be powered on or off?

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ejrossouw avatar image ejrossouw commented ·

@frank @sloanebiking May be applicable, but worth noting newer models no longer have the headphone connector and makes use of a block connector.1703933899934.png

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