nafis avatar image
nafis asked

phoenix 12/500 gets overload warning at 400VA and shuts down

I just got the 12/500 and was disappointed that the unit gives a warning at 400VA (according to a Kill-A-Watt plugged into the AC before the load). The smart dongle doesn't give any additional detailed information... just a load graphic that shows the load on the edge of the yellow/red. I thought these were spec'd and engineered much more precisely that the cheap China inverters. Guess it should be called a 12/400... Does anyone actually get 500VA out of one of these? should I return it as defective?

inverter current draw
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @nafis

There are several factors that can lead to an inverter overload. It is possible to get more than the rated power output listed in the spec in some conditions, and less in others.

Some of the other variables that impact are:

Temperature/airflow, DC battery voltage, power factor of the AC load, and more.

There is an in depth webinar that goes into more specific detail:

If after understanding the non-product factors that could be causing an overload, and still believe it is a defective inverter for your application, please fill in this form:

click here

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nafis avatar image nafis commented ·

I tested the inverter with a 400 watt hair dryer. The Kill-a-watt meter says the power factor is 1. The Victron VE.Direct Smart app gave the warning several times, then after a few minutes the inverter shut off. I'm using a Lithium Ion battery that should be able to produce 62Amps continuously. I'm not sure what wattage equates to the app load graph, but the graph was showing on the border of the yellow/red zone. The air temp was 68F

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Perhaps to further isolate the issue to the inverter, try with another load and see if there is the same problem, or if that load is very important, take the hair dryer into your Victron supplier and see if they can find a model to run it reliably.

I don't know your model of hair dryer, but I have seen some where there is some thermistor control and this can cause issues.

Have a look at the battery voltage reading in VictronConnect while running the tests, or use a multimeter at the inverter's terminals and see if there is any sag there under load.

It could be that the battery can provide, but there might be another connection issue between the battery and inverter, so the voltage is dropping.

The inverter will overload on over-current, not over-power. So a drop in voltage will increase current demand.

Also the inverter's specifications are here -

It is rated to provide 400W of continuous power at 25 degrees (inverter temp), dropping to 350W at 40 degrees (inverter temp).

The 500VA rating is for a nonlinear load with a crest factor 3:1. So your load with a power factor of 1, is going to be right on the 400W limit, and will only take a little bit of run time to heat up and derate to over that limit.

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nafis avatar image
nafis answered ·

OK sounds like it a case of Amazon misrepresentation. Nice to see the spec sheet, but the Amazon page ( ) says "Inverter, Phoenix 12V 500W 120V "... even though I guess the 500 in the product name means 500VA, it's really a 400watt inverter.

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Justin Cook avatar image Justin Cook ♦♦ commented ·

Sadly, the difference between watts and VA is frequently overlooked, if not misunderstood entirely.

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