question

chicchis435 avatar image
chicchis435 asked

Inverter voltage unstable with no load

Hello,
My inverter has recently started having large voltage spikes when there is no load on it. This quickly causes a ripple alert and the inverter switches off (displaying the error leds: Overload, Low Battery & Temperature).
It used to do this occasionally when certain appliances were plugged in, but now it does it when there is no load on it at all. Within less than 20 seconds it has disconnected.


It is a Phoenix MultiPLus 12/2500/120 installed on a boat with 12v input from a aa 400 aH lithium battery bank. I have looke

d for loose connections on the DC input but couldn't find any.


Has anyone got any ieas what might cause this?

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1 Answer
Paul B avatar image
Paul B answered ·

the Phoenix MultiPLus 12/2500/120 is a old unit.

you need to put a volt meter on the battery cable connections at the Phoenix MultiPLus 12/2500/120 and measure the voltage. it should be stable (ie not going up and down etc) if its stable then take the unit to a victron repair agent for checking. if its going up and down then look at your wiring or batteries, (ie batteries maybe flat and the batteries BMS is turning on and off etc etc

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chicchis435 avatar image chicchis435 commented ·

Hi Paul, thanks for replying.

Yes the unit is old, but I'm loathe to replace it unless I am certain it is faulty. I'd like to do as much diagnostics to ascertain that first.

I have measured the DC voltage at the Phoenix and it is stable. The is a 0.01v variation which I believe is a result of this ripple.

With no loads on the unit, and measuring for AC voltage across the 12v connections I can see a ripple of up to 1.4v occasionally. The unit buzzes and clicks at this point, and after it has happened several times, it cuts off.

This is the fault I am trying to find the cause of. Any ideas what might be causing this? I cannot find any substantial resistance/voltage drop across any of the connections between the unit and the DC batteries

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