Axpert VMIII Line Fail with Grid present

[WallK]

Hello! My PIP6048MT goes into Line Fail Warning mode (usually at night) and starts using battery even if grid is present
I thought 265V is a bit too much for it, but analyzing data doesn't show a clear correlation between voltage and this fail state

Here are some screenshots from HA, some diagrams I've made and I've attached raw data export

 

I can attach the analysis I've done if you want
Do you have ideas what could be causing this? I'm really stumped and the winter is really close now...
Thanks!

 

power_line_fail.csv line_fail_history.csv

[Coulomb]

21 hours ago, WallK said:

Do you have ideas what could be causing this?

It could be unhappy with the grid frequency, or the rate of change of frequency, or perhaps rate of change of voltage.

What's the grid like? The voltage seems to have a quite wide range, suggesting poor voltage regulation.

[WallK]

2 hours ago, Coulomb said:

It could be unhappy with the grid frequency, or the rate of change of frequency, or perhaps rate of change of voltage.

What's the grid like? The voltage seems to have a quite wide range, suggesting poor voltage regulation.

Frequency is 49.9-50.1, seems stable

Can't see correlation here

Grid is not very good, as you can see
With a pretty high resistance, considering voltage drop under power
You could be onto something with the voltage rate of change, it seems to change state on the downpeaks
But how can I prevent this? Even pretty fast voltage stabilizer (or whatever it's called) won't catch those...

Here's a clearer graph with markers when the grid fail warning changes state

Edited September 16 by WallK

[Coulomb]

4 hours ago, WallK said:

But how can I prevent this? Even pretty fast voltage stabilizer (or whatever it's called) won't catch those...

Not what you want to hear, but I wonder if the King models (original and/or King II) are better with poor grids. They have double conversion. I suspect that means that they don't have to synchronise with the grid, and so may not care nearly as much about grid quality. 

[bratpit]

5 hours ago, WallK said:

Frequency is 49.9-50.1, seems stable
 

Can't see correlation here

Grid is not very good, as you can see
With a pretty high resistance, considering voltage drop under power
You could be onto something with the voltage rate of change, it seems to change state on the downpeaks
But how can I prevent this? Even pretty fast voltage stabilizer (or whatever it's called) won't catch those...

Here's a clearer graph with markers when the grid fail warning changes state
 

I've got similar grid graph and not warnings at all .

The only issue is that on bypass,USB and SUB my modem DSL signal/noise  S/N goes to 0 and drop connection at high speed  and down it to 2.5 Mbps from 15Mb.

On SBU is OK till bus voltage not going above 400V then modem generate so many errors  so i must  down the speed a little (10Mb) to stabilize connection.

I must try some MFI RFI filters .

 

 

[esmail-kassir]

20 hours ago, bratpit said:

The only issue is that on bypass,USB and SUB my modem DSL signal/noise  S/N goes to 0 and drop connection at high speed  and down it to 2.5 Mbps from 15Mb.

On SBU is OK till bus voltage not going above 400V then modem generate so many errors  so i must  down the speed a little (10Mb) to stabilize connection.

I must try some MFI RFI filters .

can you run an external phone line without using the internal conduits to avoid interference ?

[bratpit]

On 2024/09/17 at 10:07 AM, esmail-kassir said:

can you run an external phone line without using the internal conduits to avoid interference ?

Nope. It's all connected by copper  . Router+DSL,LAN,PC Box and internet telephone.

Yesterday I added RFI filter to a surge protector where all that devices are powered an gets better but not perfect.

Was:   stable 2.6 Mbps after   DSL restart. 

Now: 10 MBps  without restarts but there is some errors and a little less S/N ratio. 

That's what happens when bypass is on. On battery is perfect all the time.

Now I can live with that.

Edited September 18 by bratpit

[WallK]

On 2024/09/16 at 3:00 PM, bratpit said:

I've got similar grid graph and not warnings at all .

The only issue is that on bypass,USB and SUB my modem DSL signal/noise  S/N goes to 0 and drop connection at high speed  and down it to 2.5 Mbps from 15Mb.

On SBU is OK till bus voltage not going above 400V then modem generate so many errors  so i must  down the speed a little (10Mb) to stabilize connection.

I must try some MFI RFI filters .

My laptop touchpad stops working when I'm near the inverter when it's charging batteries

 

 

On 2024/09/16 at 1:40 PM, Coulomb said:

Not what you want to hear, but I wonder if the King models (original and/or King II) are better with poor grids. They have double conversion. I suspect that means that they don't have to synchronise with the grid, and so may not care nearly as much about grid quality. 

Double conversion meaning they don't do true bypass to the output when in grid mode? I would love to avoid sending this voltage to my other poor devices too
I basically live on battery right now for the purposes of clean output voltage
King 1 doesn't have high PV voltage input, so I'm limited to the second one only (I'm confused at the specs, as Twin model has the frequency sync parameter, so I guess it has true bypass at one of the outputs?)

Maybe there's an option to use external charger in addition to my inverter and disconnect grid input to it? Not sure how much chargers cost, but theoretically should be cheaper than an AiO
Will it be fine charging from two sources at the same time? Or is it a very bad idea?

Thanks!

[Coulomb]

23 hours ago, WallK said:

Double conversion meaning they don't do true bypass to the output when in grid mode?

Yes. There is an AC->DC converter, followed by the usual DC-AC converter. I'm not familiar with the King II, but I believe it's the same. 

 

23 hours ago, WallK said:

I'm confused at the specs, as Twin model has the frequency sync parameter, so I guess it has true bypass at one of the outputs

I have no idea what the frequency sync parameter is about. It sounds like you can optionally ignore the frequency and phase of the input AC, but if so I'd expect that to be present in the non-twin and even the King 1 models. 

I'm 99% sure that the second output merely parallels with the first/normal output. 

23 hours ago, WallK said:

Maybe there's an option to use external charger in addition to my inverter and disconnect grid input to it?

Yes, that's an option. I ran a single inverter like that for several years. The only thing is you should set the external charger to about 0.1V lower than the inverter(s). The inverter can top off the battery on its own, and won't get confused by the battery voltage not behaving as expected. 

[WallK]

On 2024/09/22 at 7:21 AM, Coulomb said:

Yes, that's an option. I ran a single inverter like that for several years. The only thing is you should set the external charger to about 0.1V lower than the inverter(s). The inverter can top off the battery on its own, and won't get confused by the battery voltage not behaving as expected. 

Oh, that's a great advice, thank you!
Any recommendations on separate chargers?

Also, voltage under the invertor's bulk or float? I'm not sure what the logic here should be

Edited September 29 by WallK

[Coulomb]

On 2024/09/25 at 6:12 PM, WallK said:

Also, voltage under the invertor's bulk or float?

The critical time is when the inverter is considering transitioning from bulk/absorb to float stages. So it's the bulk/absorb settings that should be a tenth or possibly two tenths of a volt apart.

[WallK]

On 2024/09/29 at 1:33 PM, Coulomb said:

The critical time is when the inverter is considering transitioning from bulk/absorb to float stages. So it's the bulk/absorb settings that should be a tenth or possibly two tenths of a volt apart.

I'm not sure I understood, so let's try an example
My battery is set to 57.6V bulk and 55.2v float (in never stays in bulk, I really need to try your recently released patch)
So I would put the external charger to 57.5V, is this what you're saying?
I was thinking about putting it very low, like 54V or so, so it never fully charges the batteries with the hopes that solar will pick up the last part when available
This is considering I'm looking at constant current PSU as a cheaper option, not a real multistage charger

[Coulomb]

23 hours ago, WallK said:

My battery is set to 57.6V bulk and 55.2v float (in never stays in bulk, I really need to try your recently released patch)
So I would put the external charger to 57.5V, is this what you're saying?

Yes.

23 hours ago, WallK said:

I was thinking about putting it very low, like 54V or so, so it never fully charges the batteries with the hopes that solar will pick up the last part when available

That should work, but if there is not enough solar, then you might run out. 54 V is a float voltage, good to maintain a battery that is already full, but it will take a very long time to fully charge a battery at that voltage.

23 hours ago, WallK said:

This is considering I'm looking at constant current PSU as a cheaper option, not a real multistage charger

Oh. Well in that case, yes, you will want to target about 54.0 V, otherwise you will eventually over-charge your battery. The float voltage is the highest voltage that a battery can safely handle continuously. Such a power supply is not ideal for battery charging.

[WallK]

15 hours ago, Coulomb said:

Oh. Well in that case, yes, you will want to target about 54.0 V, otherwise you will eventually over-charge your battery. The float voltage is the highest voltage that a battery can safely handle continuously. Such a power supply is not ideal for battery charging.

In the last month I've used only 32KWh of grid power, I hope to keep it very low
Basically, for the winter the idea is -- when solar will not be available and long blackouts planned -- charge the batteries from grid and use the grid through the charger/PSU double conversion
So it won't be running ever for 24h straight
Should be fine, right? If I really don't have time (for example only 2h of grid will be available, like it was in the 2022-23 winter) -- I could raise it closer to bulk, but make sure it's not sitting there for a long time

[Coulomb]

5 hours ago, WallK said:

Basically, for the winter the idea is -- when solar will not be available and long blackouts planned -- charge the batteries from grid and use the grid through the charger/PSU double conversion

Ah, OK. When you say blackout, it sounds like you're more or less guaranteed grid supply, but only for a limited number of hours per day.

5 hours ago, WallK said:

So it won't be running ever for 24h straight

If it's at float voltage, it doesn't even matter if it does.

5 hours ago, WallK said:

If I really don't have time (for example only 2h of grid will be available, like it was in the 2022-23 winter) -- I could raise it closer to bulk, but make sure it's not sitting there for a long time

I guess so. You may need to experiment. I'm rusty on how lead acid works; I seem to recall that at float voltages, the battery just won't take much charge current, regardless of how much current the charger can supply. That's why a fixed voltage charger is so far from ideal. But since your energy needs are so low, and you seem to have access to at least some grid energy every day, it might be OK. With an LFP battery, this would be fine. With lead acid, where you don't want to regularly  go below 50% SoC, I don't know.

By the way, I'm assuming that this Power Supply Unit has current limiting. So if you set it to 54 V and the battery is at 49 V, it will just limit the current to a safe maximum (safe for the PSU and also for the battery), assuming that pushing it to 54 V would exceed at least one of those limits. Many fixed voltage PSUs won't have this capability.

[WallK]

15 hours ago, Coulomb said:

Ah, OK. When you say blackout, it sounds like you're more or less guaranteed grid supply, but only for a limited number of hours per day.

I very much hope so, I don't think we had full day without couple of hours of power yet. But it depends on rockets and stuff falling on electrical grid hardware, so no guarantees whatsoever

15 hours ago, Coulomb said:

I guess so. You may need to experiment. I'm rusty on how lead acid works

That's not lead acid, that's LiFePO with BMS attached. Actually, two of them parallel

15 hours ago, Coulomb said:

But since your energy needs are so low

I use around 8-15 KWh a day, but I still have a lot of solar energy available. This is why the grid consumption is pretty low. It will surely change during colder winter times

15 hours ago, Coulomb said:

By the way, I'm assuming that this Power Supply Unit has current limiting. So if you set it to 54 V and the battery is at 49 V, it will just limit the current to a safe maximum (safe for the PSU and also for the battery), assuming that pushing it to 54 V would exceed at least one of those limits. Many fixed voltage PSUs won't have this capability.

Some sever PSUs are current limited, not just protected, some are not. And not everyone specifies. There are Aliexpress "chargers" that are basically server PSU with some PCB with a pot that should limit current to whatever I want. They look kinda dodgy, to be honest, but cheap as chips.
Batteries can eat up 200A without complaining (theoretically, I can provide only 100A from the inverter), I can't afford this big of a PSU and it will be just scary
Plan is to get ~50A ~60V current limited PSU or add a current limiting capability to one without so it doesn't turn off or die the second I attach it to batteries

[Coulomb]

4 hours ago, WallK said:

That's not lead acid, that's LiFePO with BMS attached. Actually, two of them parallel

Ah, it must be 16S charged to 3.6 VPC average. I only charge mine to 55.2V. 54V is 3.375 VPC, which is slightly above the really flat part of the LFP voltage versus SoC curve, so your LFP battery should charge fairly well to a fixed 54.0V. Much better than lead acid would. 

[WallK]

21 hours ago, Coulomb said:

Ah, it must be 16S charged to 3.6 VPC average. I only charge mine to 55.2V. 54V is 3.375 VPC, which is slightly above the really flat part of the LFP voltage versus SoC curve, so your LFP battery should charge fairly well to a fixed 54.0V. Much better than lead acid would. 

My BMS requires higher voltage to drop into OV protect mode and start balancing
With Voltronic solar charging behavior -- it's actually is charged to 55.2 like yours are
Thanks for the information, really appreciate it!