Any risk of damaging my multyplus when the inputs voltage is low?

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escaping-swedes asked Mar 22, '20

Any risk of damaging my multyplus when the inputs voltage is low?

I have a multiples 12/3000/120 120v inverter/charger

I have this multiplus connected to Victron lithium battery’s.

Now to my problem, I have an American RV in Europe (that’s why the 120v inverter) for shore power I use a transformer to convert 230v 50hz to 110v 60hz now lately the transformer is given me problems and only producing 85-95 volts output. The Victron multiplus then reduces the watt input but still charging my battery’s with 350-180 watts.

I don’t get any notifications on my color controller but I can see that the line in is giving low voltage.

Now the plan was to get the transformer fixed but we are currently in lockdown in Spain, and now it’s been raining for four days so Even 300 watts input power would be nice to have but I don’t want to damaged the inverter or anything else.
Is the low voltage input dangerous for the inverter?

Thankful for any answers // Henrik

MultiPlus Quattro Inverter Charger

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Answer 1 · 2020-03-22T20:02:02Z

Charlie Johnson answered · Mar 22, 2020 at 08:02 PM

@Escaping Swedes

Let's discuss your transformer problem first:

Transformers are generally designed to work on either 50Hz or 60Hz, although there are some that are designed to accept either. Fundamentally, transformers will accept a primary voltage and either boost (raise) or buck (lower) that voltage to deliver to the taps on the secondary windings. Transformers do not change the frequency; i.e., 50Hz input yields 50Hz output and 60Hz input yields 60Hz output. If your transformer is not designed for dual frequencies, it will fail.

Now the Multi"

The Multi will accept a lower voltage, settable with VEConfig, but there is no such thing as a free lunch! Power in = voltage in x current in and Power out = voltage out x current out (assuming perfect efficiency for the Multi). And, with 100% efficiency; Power in = Power out. Reducing the Power in will produce a lower Power out. A Multi can only transfer the power; it cannot produce power.

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escaping-swedes commented · Mar 22, 2020 at 09:07 PM

Thanks Charlie for your answer.

For the transformer mine seems to be designed to change the frequency output from 50hz to 60hz it also shows on the display 60hz output.

The transformer was already installed when I bought the RV and the company that sold the transformer don’t have any service or support for this product but in short it has worked fine for 2 months and now it gives the right output voltage for about 30minutes after turning it on then the voltage drops to 85-95 volt. The frequency is the same (60hz)

For the multiplus, in this situation I am in now, I only want to charge the battery’s some during this rainy period. I can se on the color control that the multiplus sends the same voltage out when connected to shore power so I make sure not to use any devices on 120 volts when the shore power is connected.
but it charges the battery’s 15-20 amps so it’s something at least for now.

Thanks for all your help. If you have any ideas on the transformer please let me know.

Thanks // Henrik

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Answer 2 · 2020-03-23T19:00:11Z

Charlie Johnson answered · Mar 23, 2020 at 07:00 PM

@Escaping Swedes

OK. Thanks for the update. First principles are that true transformers can only change voltage, they absolutely do not change frequency.

Now to your problem. I tried to track down a techman for your unit and went down a rabbit hole on an old forum filled with vitriol between RV Transformers and one of their installers. It was not pretty. Since your experience and the label shows 50Hz in and 60Hz out I can only surmise that there are other electronics in the box. I am guessing that the incoming 205-253VAC @ 50Hz is first rectified to direct current (DC) at approximately the same voltage as that incoming; i.e., 230VAC is rectified to 230VDC. This is then conditioned by an inverter section that inverts the 230VDC to 120VAC @60Hz.

There is probably more to the conditioning then the bare basics I have guessed out; there may be pulse width modulation (PWM) of the HVDC to drop it to LVDC at 120VDC before inverting, etc., etc.

A really good electronics (not electrical) shop may be able to at least troubleshoot the unit. Replacing parts is going to be difficult.

You understand the Multi voltage in/out so good luck. Sorry I can't be of more help.

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Answer 3 · 2020-03-23T19:44:43Z

jaywolfe answered · Mar 23, 2020 at 07:44 PM

rv transformers i believe are no longer in use by many people. I believe there product had some issues.

In the long term you will need to replace this item not repair it

We use a victron Isolation transformer into a Quattro. I believe many converters in the u.k. use a compnay call birminhgam transformers also. I understand the issue with the Htz but it hasn't caused us any issues thus far, the 120v quattro accepts the 120v / 50htz supply no problem.

I cant comment on the multiplus receiving the 85volts but i thought you should know the state of play with rv transformers ltd. Its worth a google if you want to find out more

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