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dgnoise asked

Phoenix inverter ECO mode issue with refrigerator

Hi everyone,

I am a very happy owner of a VE Phoenix inverter 12/500, attached to my solar off-grid system.

I'm using the most efficient refrigerator on the market, the Liebherr TP 1720 which averages to a mind blowing 7W power consumption which for a inner size of 145 liter is just insanely low.

While running the inverter in always ON mode everything works great and this inverter can easily handle the inrush current required, and eventually I am averaging at 11-12W consumption with the overall system, which I really can't complain about.

However, considering that the ECO mode could potentially cut another 5-6W to the above figure it would be great to take advantage of it. Unfortunately it doesn't seems to work with my setup.

When I set this mode, if the refrigerator is cold enough and doesn't require the compressor to start everything runs fine, but as soon as the refrigerator needs to turn on I get an error on the smartphone app related to something like "HIGH AC output alarm". Not sure what is the reason since I can't find much documentation on this error. All I can say is that I just have the refrigerator connected (with its original cable) to the inverter's AC output and nothing else.

When I get this error I just need to switch (on the phone app) to OFF and then to ON and the compressor starts just fine. I'm puzzled about the possible cause.

Concurrently I was just wondering whether the pulse sent in the ECO mode is long enough to allow the fridge's electronics to figure out whether it needs more power or not.

No matter what, to me it would be really great if the pulse duration could be configurable within the app, just like the interval between pulses.

I really would appreciate very much is VE could elaborate more on this topic.

Thank you very so much in advance for an answer and... for making such great products!!

(Just as a curiosity this above mentioned fridge uses a SECOP HXD30AA compressor)

Phoenix Inverteroffgridsolarinverter current draw
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criftins-campers avatar image criftins-campers commented ·

I think I have either the exact same issue or something very similar.
I am using an Inventor A++ fridge rated at 40W and exactly the same 12/500 Phoenix Inverter.

It works fine when the inverter is on all the time, but that defeats the object of buying the relatively expensive Victron i.e. specifically for the Eco mode.

However when the Inverter is set to Eco the fridge, about one time in four, does not switch on properly when the thermostat is calling for power, the compressor stalls instead.

The way the Inverter seems to be polling to check for demand (i.e by providing a brief 240V spike every few seconds) seems to provide just enough power to cause the compressor to start momentarily.

A few seconds later when the Inverter kicks in properly, to meet the demand my compressor then randomly stalls.

During the stall I can then see that the inverter is running at around 80% and occasionally I also get a high AC alarm.

This persists until the fridge stops trying to run the compressor so it continues in this stalled state for a good minute or two, and obviously during that time the current has remained high wasting vast amounts of energy in the battery.

This may also be lead to overheating and eventual damage to the compressor.

This is really annoying, last thing I expected was for the Eco function to have issues!

I am using the Windows application.
Unfortunately I can now see it is very very limited in its functionality.

I can only change the polling time and wattage but I can't change (delay) the reaction time

I think if I could delay the inverter from starting up once demand is seen to, for example, 1 minute this may give the compressor time to recover from the polling spike that causes the stall and it will then start up properly every time.

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criftins-campers avatar image criftins-campers criftins-campers commented ·

PS I am going to change the polling time from the default 3 seconds to a minute, I don't think it will make any difference but I need to do something because as it stands the Inverter is using more energy than the fridge whilst not in Eco mode!

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criftins-campers avatar image criftins-campers criftins-campers commented ·

PPS The inrush current causes my inverter makes quite a loud momentary hum (for want of a better word) each time the fridge calls for power.

Does yours do the same?

I had not expected that either as that will affect us in our Motorhome when asleep. I do hope I have not made a bad buying decision and chosen the wrong Inverter, on paper it should be able to easily cope but.......

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jasontav avatar image jasontav criftins-campers commented ·

My compressor fridge (actually a top loading chest freezer with a thermostat controlled mains connection that allows me to set the internal temperature and compressor start delay etc.) uses about 1kW to start successfully (I have it connected to a 3kW Multiplus)

Now the Phoenix 12/500 has a peak power (surge) of 900W.

So if your fridge is taking near to that everytime it starts, then yes you'll hear a clunk. For reference, I can hear my multiplus when it does start the fridge, but its not very loud or concerning.

Personally, I wouldn't want my inverter hitting the surge limit everytime the fridge starts. In my case (cheap freezer as above) thats a few times an hour.


just my 2 cents.

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criftins-campers avatar image criftins-campers jasontav commented ·

I think you are right the inrush current even for this modest fridge is probably near the Inverters limit

I haven't yet determined where the noise on startup is coming from. It might be the compressor rather than the inverter.

The high voltage alarm only happens on the eco setting, the Inverter seems to be able to cope with the Fridge inrush current ok every time on the normal setting and does not alarm

The sad thing is I have a perfectly good Stirling Power Inverter and only bought the Victron specifically for running a low energy fridge to benefit from the Eco settings

I will probably return it to the distributor as not fit for (my) purpose.

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criftins-campers avatar image criftins-campers commented ·

I have now tested this with two identical fridges just in case on of them was faulty both compressors stall randomly on Eco mode using the Phoenix 12/500 Inverter, and both trigger high voltage alarms when stalled.

I am now in the difficult position of do I risk wasting another £100+ on the next model up the 12/800 only to find that's no good either! I think the answer to that is no it is not worth the risk.

I will return my Phoenix for a refund and buy a cheaper more powerful sine wave based inverter instead from elsewhere.

As an aside I have from one of my ex Ambulances a Sterling Power 1800 Quasi sine wave inverter which I have also done some tests on before ruling it out as well.


The modified sine wave is not efficient, the fridge draws approx 40 watts on the pure sine wave Phoenix but > 55watts on the Sterling power one!


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klim8skeptic avatar image klim8skeptic ♦ criftins-campers commented ·

1 last thing you should try, Really short leads from the battery to inverter (don't forget the fuse).

Or you could use thicker able.

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criftins-campers avatar image criftins-campers klim8skeptic ♦ commented ·

Yep my inverter is in the battery locker within inches of the 4 deep cycle batteries and everything is correctly fused and uses huge cables. The Ambulance originally had a Xantrex inverter but that had been robbed out before I bought it.

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2 Answers
dgnoise avatar image
dgnoise answered ·

Couple of things worth mentioning:

1) You should start by finding out the model of your compressor by taking a peek on he back of your fridge. With that you should be able to find its datasheet and in there there is a spec typically called "cut in current" stating the current required at startup. By multiplying that times your voltage you can figure out how much is the peak in Watts and determine whether your inverter is properly dimensioned. This for example is my compressor's datasheet: https://www.secop.com/fileadmin/user_upload/SEPS/datasheets/hxd30aa_cdo00097_r600a_220v_50hz_11-2016_desd563i102.pdf

2) With the above being said I would distinguish between the error messages you get. The "overload alarm" message is a clear statement meaning your inverter is not powerful enough (most of the time just because of the in rush current required). If you didn't get this error I don't think the 12/800 model will necessarily help the ECO-mode issue.

Messages like "low battery voltage" just imply you battery is not big enough to handle the current peak required on the 12V side during the initial inrush current phase.

The few information related to the "High AC voltage" alarm I found are not entirely clear to me, mentioning something about the wires used on the AC side. But still in my case I do not understand the real reason for this alarm.

3) I have been monitoring the consumption of my fridge for quite a bit and I did notice that even if tipically the consumption cycle is ~30W / 0W when ON/OFF somwtimes I saw it jumping up to 200W for extented period of time (up to 5min or so). Even if I am not entirely sure the reason for this I can tell that this is not related to the ECO mode pulses. Just normal behavior when the fridge is connected to the regular home 230V outlet. This to me means that for whatever reasons sometimes the compressor finds itself in a state in which it draws way more current then normal. My feeling this is the same state you are referring to when you say "the compressor stalls". If that is the case I would consider this state still normal behavior since as mentioned I saw it happening more than once on a new fridge running on 230V (no inverter). With that being said it is entirely possible that this is caused by the motor stopping in a specific position that for some reason is not favorable to restart, but at least in my case it eventually recovers.

4) I don't know about your case, but in my case the off grid solar system is installed up in a hut in the mountains which can only be reached after 45min of steep uphill hike. For this reason I need to thrust my inverter, which means I have no problem spending a couple hundred dollars more for a quality inverter. In the case of Victron Energy products I have been very positively impressed with their quality, so personally I would think twice before going to a cheap/no-brand inverter.

5) Last but not least, the ECO-mode is not the only highlight of the Phoenix inverter. It's low zero-load consumption is also pretty good. So in your case, if we are talking about a 40W fridge you should just add 5-6W of the inverters consumption which in terms of percentage means an increase of less than 15%.

6) One more.... the point I was trying to make is that in my view the problem we are experiencing in ECO mode is more related to the pulse width. This appears to be confirmed by the fact that everytime I would get the High voltage alarm by switching to OFF and then back ON it would always recover (I was doing this from the phone app, not even from the physical switch). And BTW, I personally perfomed all my test with the interval set to 60s, because in a fridge I do not think a 3s poll or so is required. In addition my gut feeling is that a compressor might not enjoy this pulses of current slaps overtime.

This are really just my 2 cents.

Thank you very much for your inputs, it is very helpful to share experiences with other people with the same issue. I would be nice though having someone from VE step in as well.

Thanks a lot

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k-k avatar image
k-k answered ·

The 200w could be a defrost or oil-heating load.

Very short polling-time may give some crank's which build up pressure. Higher pressure higher inrush, so poll every few minutes (3-5min or longer) and for 2-3seconds long. Just count out the seconds via ear to estimate the fridges start-up time and add a second.

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Related Resources

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Victron Offgrid page

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