Multiplus II - Warnings & Alarms

[Logic28]

I am getting a surprising number of L1 overload warnings from my two Victron Multiplus 5000 in parallel system with 20k battery storage.
here is an example from yesterday's log:

76

VE.Bus System [276]

Overload L1: Warning

2024-04-28 15:01:00

20s

The usage at the time was nowhere near any limitation of the system as can be seen by the images, a mere 1286w on L1at that specific time.


Often these messages are accompanied by a "low Battery" or a "ripple" alarm but not always.
The battery pack is made out of a 1x16Kw perfectly cell-balanced unit connected with a 2/0 (70mm) cable and a 5kw unit also connected to the Victron Power in via a 1/0 (50mm) cable.

I cannot think of a setting that I might have missed causing these alarms.

 

[Logic28]

Any Ideas?

 

[Brucey]

Try removing the 16kWh battery from the power in, and vice versa.

 

[Q-Dog]

Try removing the 16kWh battery from the power in, and vice versa.

Are you thinking one of the batteries is shutting down?

 

[Brucey]

Are you thinking one of the batteries is shutting down?

Yeah maybe bad cell or something like that, if the cabling is sufficient as it seems.

There's some discussion here (if we rule out undersized wires, insufficient battery and inadequate crimps)

Victron MPII Inverter Overload

@plonkster , hoor my lied … This is 100% correct, I don’t dispute the tests at all. Must be done. BUT, here is the thing. I can show you, and Victron, that with: 70mm2 cable (<5m return) OR 50mm2 (<2m return), Professionally hydraulically crimped lugs, BMS interfaces with Venus, … that I...

energytalk.co.za

 

[Q-Dog]

Yeah maybe bad cell or something like that, if the cabling is sufficient as it seems.

There's some discussion here (if we rule out undersized wires, insufficient battery and inadequate crimps)

Victron MPII Inverter Overload

@plonkster , hoor my lied … This is 100% correct, I don’t dispute the tests at all. Must be done. BUT, here is the thing. I can show you, and Victron, that with: 70mm2 cable (<5m return) OR 50mm2 (<2m return), Professionally hydraulically crimped lugs, BMS interfaces with Venus, … that I...

energytalk.co.za

When I saw additional "low battery" alarm I thought the same thing.

 

[Logic28]

Try removing the 16kWh battery from the power in, and vice versa.

I had the same problem when the 16kw battery was not there.
Perhaps I should try isolating the 5kw from the system but it makes no scientific sense at all, if one battery was going on its knees for whatever reason, the other one would cover it, especially on such a low demand.

 

[Logic28]

Yeah maybe bad cell or something like that, if the cabling is sufficient as it seems.

There's some discussion here (if we rule out undersized wires, insufficient battery and inadequate crimps)

Victron MPII Inverter Overload

@plonkster , hoor my lied … This is 100% correct, I don’t dispute the tests at all. Must be done. BUT, here is the thing. I can show you, and Victron, that with: 70mm2 cable (<5m return) OR 50mm2 (<2m return), Professionally hydraulically crimped lugs, BMS interfaces with Venus, … that I...

energytalk.co.za

Thanks, very interesting discussions on your link however in my case, the problems are multiple but not in combination, I sometimes get a DC ripple, other times a L1 overload and other times low battery warnings even with batteries over 85%.

My 16kWh battery is as perfect as it could be, I spent 48 days testing each cell before installing them with the Seplos 200E in the custom container, all cables internal and ext. are 70mm (max length 2.5m each way so 5m between positive and negative return), all lugs crimped with 16T hydraulic crimper after having test/cut some of them to verify their air tightness.
All bus bars show 5mΩ resistance.
All cells are within 2mv of each other at all times and have been since day one.
All terminals have been checked for torque several times during the 4 months in service.
The only items I cannot vouch for are the Chinese DC battery isolators and I would not know how to properly test them other than with a resistance tester which I shall do next.
The 5Kw Battery is an unknown quantity but also its cells don't seem to deviate more than a few millivolts.

 

[Logic28]

When I saw additional "low battery" alarm I thought the same thing.

The low battery alarm is more often not in conjunction with the L1 Overload, only sometimes and only under high load demand.

 

[Brucey]

Thanks, very interesting discussions on your link however in my case, the problems are multiple but not in combination, I sometimes get a DC ripple, other times a L1 overload and other times low battery warnings even with batteries over 85%.

My 16kWh battery is as perfect as it could be, I spent 48 days testing each cell before installing them with the Seplos 200E in the custom container, all cables internal and ext. are 70mm (max length 2.5m each way so 5m between positive and negative return), all lugs crimped with 16T hydraulic crimper after having test/cut some of them to verify their air tightness.
All cells are within 2mv of each other at all times and have been since day one.
All terminals have been checked for torque several times during the 4 months in service.
The only items I cannot vouch for are the Chinese DC battery isolators and I would not know how to properly test them other than with a resistance tester which I shall do next.
The 5Kw Battery is an unknown quantity but also its cells don't seem to deviate more than a few millivolts.

What kind of Chinese DC battery isolators?

 

[Checkthisout]

You posted power draw but did not show what battery voltage was at the time of failure.

Going to guess you have a BMS tripping off or a bad connection causing voltage droop.

 

[Logic28]

What I need to understand first of all is how the Victron Multiplus calculates the overload.
Are there any settings contributing to the issue that could I have missed?
I could understand this happening on one inverter only but since I added the second one running in parallel I now have 10.000 KVA (~8.000 w) available so anything below that should not trigger any warning.
The next thing is understanding the DC ripple fundamentals as I am new to that and I shall research now.
The battery low syndrome could well be a case of a bad connection which I shall investigate also testing each battery isolator for resistance.

What kind of Chinese DC battery isolators?

This was before the second Inverter was installed, I now have four battery isolators and only using two of them.

 

[740GLE]

The looks like the same ones victron rebrands.

 

[Checkthisout]

What I need to understand first of all is how the Victron Multiplus calculates the overload.
Are there any settings contributing to the issue that could I have missed?

Battery voltage at the time of failure meaning the voltage the multiplus or whatever at the time of failure, not voltage at the battery.

I could understand this happening on one inverter only but since I added the second one running in parallel I now have 10.000 KVA (~8.000 w) available so anything below that should not trigger any warning.
The next thing is understanding the DC ripple fundamentals as I am new to that and I shall research now.
The battery low syndrome could well be a case of a bad connection which I shall investigate also testing each battery isolator for resistance.

The Ripple can be the result of voltage fluttering due to a BMS malfunction.

 

[Brucey]

Yeah that pricing can't be far off the real Victron 275A one that's rated for 48V nominal systems.

https://www.amazon.com/Victron-Energy-VIC-VBS127010010-Battery-Switch44/dp/B095X94JXF

 

[Logic28]

The looks like the same ones victron rebrands.

These isolators? Victron have similar ones in its range?

 

[Logic28]

These isolators? Victron have similar ones in its range?

Yeah that pricing can't be far off the real Victron 275A one that's rated for 48V nominal systems.

https://www.amazon.com/Victron-Energy-VIC-VBS127010010-Battery-Switch44/dp/B095X94JXF

I also have two of these still in the box but I see no difference, I need to dismantle one and check how good the sprung-loaded connection is

 

[ricardocello]

Often these messages are accompanied by a "low Battery" or a "ripple" alarm but not always.

I get L1 and L2 overloads sometimes, they clear, I ignore them.

But low battery implies that the DC voltage at the input of the inverter has dropped below the threshold (depends on settings).
You’ve got a Cerbo GX, can you zoom in on VRM on voltage numbers, maybe the inverter or other device caught how low it was.

Is this an ESS? Is PowerAssist enabled if no ESS? Is this while running on inverter?

 

[Logic28]

You posted power draw but did not show what battery voltage was at the time of failure.

Going to guess you have a BMS tripping off or a bad connection causing voltage droop.

Battery voltage at the time of failure meaning the voltage the multiplus or whatever at the time of failure, not voltage at the battery.



The Ripple can be the result of voltage fluttering due to a BMS malfunction.

I assumed that the ripple was due to incomplete suppression of the alternating waveform after rectification as stated in the technical description so the only way for the BMS to create one would be in the form of PWM . . ?

Let me check the voltage at the inverter at the time, that is if the VRM has this feature

 

[Logic28]

I get L1 and L2 overloads sometimes, they clear, I ignore them.

But low battery implies that the DC voltage at the input of the inverter has dropped below the threshold (depends on settings).
You’ve got a Cerbo GX, can you zoom in on VRM on voltage numbers, maybe the inverter or other device caught how low it was.

Is this an ESS? Is PowerAssist enabled if no ESS? Is this while running on inverter?

Yes, even mine clears after 20 seconds or so but it happens often, sometimes even twice the same day.
Here are the voltage and consumption values at the time of the issue. I assume that the Lynx shunt is the nearest thing to the Inverter voltage as there is no widget for the Multiplus.