False (or at least strange) Overload L1: Alarm on Multiplus 2

Q&A and troubleshooting
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Looking for some assistance from the community regarding a DIY installation (since spring 2023) with “strange” alarms these last weeks.

For information, some details of my setup:
I have a MultiPlus-II 48/5000/70-50, CerboGX, MPPT 250/60, 3600Wp solar panels and 48V LFP battery (16x 280Ah prismatic cells) with JK-BMS.
As I’m located in the South of France and the solarpanels are full South oriented, I’m benefitting of a lot of “good sunshine”. I rarely need electricity from the grid, but for “security”, I am still connected to the grid.

BUT: most of the year the MP2 is in “Inverter only” modus, so no input/export from/to the grid.

I have no “sell back” contract with the regular electricity company, as this would require a costly inspection of the system and a costly contract without any benefits for me. I consume about all my production in sommer (pump of swimming pool and AC use most of my production) and in winter time I only need rarely grid connection.

These last weeks I have regularly an “Overload L1: Alarm”, although I’m not going above the 5000W max. “capacity” of my MP2. See example picture here after, arround 12:05.

At that time we had an oven and 2 electric cooking plates and some lights and a central heating pump “on”. But as you see, the peak consumption was only about 4.750W for a short time.
This is below the max. capacity of 5.000W of the MP2, so this should not have triggered the alarm.
Even if it would have been for a short period above 5.000W, the MP2 should be able to coop with 9.000W max. (as stated in the Data Sheet and User Manual)

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Recently, we have had these alarms (and shutting down) more often than earlier. And these times I couldn’t find any peak consumption above 5.000W. Whereas in past time, I did find higher consumption in the graphs (above 5.000W) when the shut down happened. Which was logical, so I didn’t wonder at that time…
But now I can’t find any reason for these shut downs.
Fortunately the system restarted each time after some 20-30 seconds.

So my question is why this happens ? Has the age of the MP2 any influence on “max. capacity” ?

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The Multi Plus 2 5000 … has 5000VA and not 5000W …
The heating plates … if they are not induction … would be a wonderful active power.
Your pump and lighting are not purely active loads … they are apparent Loads …
So the Multi is operating just above the limit, at least when your pump starts up.
That could be the cause of the brief “overload messages.”

The translation for
active power W
apparent power VA
reactive power Var
could lose its meaning in translation.

1 Like
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Thanks for your reply Steffen.

You’re correct regarding VA and W indications… I forgot/missed that…
Nevertheless, the DataSheet of the MP2 also indicates 9000W as peak performance. So a short peak of 4750W should’nt trigger the shutdown in my view.

I also checked my VE-Configure settings, and I use 240V as output voltage (as this is what is used in my region as grid voltage), but in the Manual/DataSheet of the MP2 I find only “Output voltage: 230 VAC ± 2 %”. Could this create “false” indications of max. output power ?

And to be clear, I did not only get warning message, but the system actually shut down for about 20-30 seconds. Again, which should not happen as I’m well below 9000W peak power. I do agree on getting a warning message (which is good by the way, as we could lower the consumption instantly in the kitchen, for sure withing a few seconds of the warning alarm), but the system should not shut down for such a short “overload”. At least that is what Victron claims on their system…

Or, does the MP2 doesn’t support the 9000W peak capacity when only connected to Battery, and not to both grid and battery?
It could be that the MP2 does not “allow” the input of the needed power only from batteries.
I could not find any information on the max. battery input power into the MP2…

As said in my initial post, I only have “battery power” for 95% of the time (not connected to the grid).
My BMS allows 200A continous load (at 48V this 9600W, at 55V this is 11.000W) and 350A peak for about 30 sec. But this was not the reason for the shut down of the system as the alarm was on the MP2 and not the BMS.

FYI: Heating plates are induction, the pump is/was running continously at about 45W (it is a pump for a wood boiler stove, which does not switch on/of during the use of the wood boiler between about 7AM and 9PM), and the lighting is 40W LED in total, also continously “on” in the kitchen as we have little direct natural light.

Looking forward for your input.
Best regards,
Jan

4

Induction hobs place an enormous strain on the toroidal transformers in Multis and Quattros. The assumed power can be considered to be around 0.5 times the actual value. Since the power of induction hobs is pulsed electronically via HF transformers in the hob, the “old” Victrons do not like them at all…
This MAY be the reason for the shutdown… but it doesn’t HAVE to be.
The veeeery small pump and the LED can’t be the reasons.
Did you log the battery voltage at that moment… You may be entering a shutdown range… that would be a reason for the relatively long shutdown period…
What voltage values are specified here in the JK-BMS? Does your GX communicate with the JK?

ps .. maybe a fridge in the kitchen ?

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What about the temperature? The warmer the less you can pull from the inverter. This can also be found in the datasheet.

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  • Yes, BMS and CerboGX communicate with each other.
  • What do you concider to be an “old” MP2 ? Mine dates from january 2023.
  • Yes we do have a fridge/freezer in the kitchen (peak consumption 170W) and a freezer in the basement (I don’t know the exact power consumption, but I assume about the same)

Below, the Victron DC-Bus information from around the time (12:05-12:10) the shut down happened.
Clearly the battery was well/enough charged… (all Voltage above 51V on a 48V battery is OK)

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Same information registerd by the BMS (and transferred to the CerboGX):

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Also on individual cell Voltage, there was not an issue. Lowest cell at that time was 3,15V (highest at 3,25V):

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Shut down from battery side should not happen at these values. BMS only shuts down at 2,6V lowest single cell voltage. But then the battery pack is already wel below the 48V …

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Temperature in the basement where the Victron and Battery pack are installed is year round 15-25°C. (winter - summer)

edit: currently 19°C as measured by Victron temp. probe and BMS temp.probes give 19,3°C and 19,6°C

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Ok that is fine for the MP II. I would however keep a close eye on the battery temperatures as at 10°C you may start hurting the batteries and the closer you get to 10°C will slowly have an impact in the long term.

This is not, yet, some widespread news, but I can assure you that some people will get in trouble because of this as too many people are running at 10°C and lower in winter time,

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As said, batteries NEVER went below 15°C in the past 2 winters. So no reason why they would get different temperatures this winter…
The setup is in the south of France (it hardly ever freezes at night and during the day temperatures always raise), and my basement is half underground, so very stable in temperature. And all is installed below a staircaise which is enclosed in winter, so temperature stays even more stable…

But how could this influence the shutdown of a few days ago, when temperature was about 19°C ???

10

Just had another thought about this…

All my AC consumers (my in-house installation) are connected to the L1 AC-out (= critical loads) of the MP2, and most of the time the MP2 is only powered by batteries.

Could it be that the L1-output is restricted to the “standard” capacity, and is not able to get the full 9000W “peak” performance ?

As no AC-in is connected, all power comes from my batterie and the DC-AC conversion in the MP2 is limited to the “normal” performance (5000VA / 4000W) and no peak-performance (9000W) is possible without AC-in connection. If so, the peak I noticed at shut-down of the system is indeed over the limit of 4000W and would clarify why the MP2 shut down.

Just my thought, any return on this would be appreciated.