renzer23 avatar image
renzer23 asked

Phoenix 12/800 Shutting Down (not overload - not setting related)


My unit is shutting down when I plug my 350w charger and that there is only the batteries, 6x 90Ah AGM, they are a bit tired but still stay around the 12.3v when loaded with the charger.

This charger was liable to conflict with another el cheapo PSU, being my fridge, this is resolved as I was able to put the fridge on straight DC. I did just check the default parameters through Victron Connect and the Low Battery Restart and Alarm is set at 10.30v, the Low Battery Shut Down is set at 9.30v.

I do not recall seing the voltage dropping below 12.3v while charging with no direct sunight. The batteries were indeed able to supply enough power to the Phoenix for a long 6 months without any issues. It could be the batteries getting worse and worse, however, those are Lead Acid and the transfer curve for voltage variation transients is rather a slow knee therefore, I woud see the voltage getting to either the 10.30v or either 9.30v if it would indeed go there during a charge.

I will check again later on as now everything is fully charged, just to confirm, and to add more details about any faults. I might be wrong in my observations, so if anything comes to mind to anyone in here that may help with that in the meantime that I come up with more numbers, please do let me know.

It's not very urgent as it's still the summer and we get plenty of strong sunlight to charge everything up during the day, however, in the winter, it may get more anoying.


Phoenix Inverter
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5 Answers
seb71 avatar image
seb71 answered ·

If with the same load it only shuts down when the panels are not producing power, probably it's not the inverter.

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renzer23 avatar image renzer23 commented ·
I'm sorry but I fail to understand your reply. Would you please elaborate?
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seb71 avatar image seb71 renzer23 commented ·

What I got from your original post:

  • When the inverter gets power from the MPPT/PV panels, the inverter runs fine.
  • When the inverter gets power from the battery, it shuts down.

In both cases the inverter powers the same load (that charger).

If this is accurate, then the cause is the battery, not the inverter.

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renzer23 avatar image renzer23 seb71 commented ·
This is very likely, however, since the voltage remains above 9v, then the inverter should handle it. I have updated the poste with the response from the dealer below.
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renzer23 avatar image
renzer23 answered ·

Dear Seb71,

The charger delivers 13.5v at all times in bulk and float, and above 14v in absorption.

The battery bank does go down to 12.3v as mentionned and it's normal under load, it has been verified on the BMV display. Then why is the inverter shutting down, even though it is set to at 9v? Do you want me to post a video to illustrate my question?

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Alexandra avatar image Alexandra ♦ commented ·

It is not always voltage related. Some batteries when they fail stay at 12 or 13v but can do nothing. Are any of the batteries sides no longer flat (use a ruler) if they are bulged they are done.

There will be higher resistance in the battery due to age, this will "oppose" the current draw the power supply needs to start up. While it is 350W rated it does draw more than that on first plug in.

If you eliminated the issue when using the mppt then it is the batteries.

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renzer23 avatar image
renzer23 answered ·

Here is the response I sent to the dealer:

Dear Axel,

Here is my answer:

There are chances that the voltage of the batteries drops too low in voltage

12.2v at the lowest displayed on the BMV

therefore the amperage increases and the inverter goes into default by the increase in amperage.

If the voltage goes down, then the amperage will go down. I don't know of a single battery on the market that will increase amperage because its internal resistance has increased. If so, maybe we'd have some free energy, which would be great to exploit in the future.

The more the batteries are used, the more the voltage drops when you have a current draw.

These batteries are a bit tired, however, given the number of cells, 500w does indeed drop the voltage to not more than 12.4v from when they are new. Delivering 500w shouldn't be a problem for the inverter, period.

The compressor can draw quite a large current draw. The inrush current as well as the wear of the batteries would explain the failure of the inverter.

It's a generic brand Lithium battery charger, while the one I had previously was a Swiss brand, maybe that's the problem. In my humble opinion, incriminating the inverter is probably on the wrong track.

1 - It will run for 5-10 seconds (this dismisses the ignition claim)

2 - The voltage drops to 12.2v

3 - The inverter shuts down of an alledged overpower.

I think it's an internal conflict due to the electronics of the charger which has too few protections. Or else, it's still this low-end cooler that's making a big deal out of it.

I'll try unplugging the cooler, and if that doesn't work, I'll try running 500w at home with a more robustly designed device and get back to you with the outcome.

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renz avatar image
renz answered ·

I did a test at home today with Victron Connect. It displays the correct voltage 13.3v, same as the monitor.

When I put the charger online, it draws the usual 300 odd watts but the software gives a battery low voltage warning displaying 12.0v. The battery monitor displays 12.6v as its under load, this one looks normal as I have over 500Ah on AGM batteries fully charged.

At this stage, I would trust the battery monitor as (I'm well rounded with battery experiments, it's my job) the result from the inverter seems to be stuffed.

A few seconds later, the inverter shuts down as for him, the battery voltage is down to 11.9v (we are still way off the 9.3v cut off but...) and the monitor continue displaying something more consistant around 12.6v

I did indeed ran a test with another load. I have a concrete drill that uses 500w. The inverter delivered the full power for a few seconds, however, the exact same thing happens.

It was noted that if the sun is shining, this will happen as well, however it will keep the shut down occurring.

We have discrepancy between the 2 meters. I have no clue at this stage why the inverter is so pessimistic with its voltage read. The system is wired up exactly like on the BMV diagram.

My question is: How does the inverter gives a false reading of the voltage that is consistant with the load curve but is however exaggerated?

And then: What can I do to fix that fast, do I have to make the BMV master of the circuit?


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renz avatar image
renz answered ·

To the top

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