Hello, I am a new member, I have a 3kv inverter vm iii, and I am facing the problem of the wrong reading on the inverter screen, in addition to the consumption of current from the batteries, although the energy of the panels is sufficient, version u1: 47 00, u2:19 15 any ideas?

a

 

 

4 hours ago, Amjad Kazem said:

Hello, I am a new member, I have a 3kv inverter vm iii, and I am facing the problem of the wrong reading on the inverter screen, in addition to the consumption of current from the batteries, although the energy of the panels is sufficient, version u1: 47 00, u2:19 15 any ideas?

a

 

 

Welcome on the forum. 

Can you perhaps share pictures of the load and battery current as well as the PV value as this would help. 

I'm assuming that you have a battery with some sort of BMS, and it's connected to the inverter via a suitable cable, and that's why the battery icon is flashing.

28.0 V would be 3.5 VPC if it's an 8S LFP battery (i.e. 8 Lithium Ferrous Phosphate battery cells in series means an average of 3.5 V per cell). This is consistent with a full battery. The 1 amp of current is inconsequential.

So I'm not seeing an actual problem here. If there is, please explain the problem in more detail.

9 hours ago, Coulomb said:

I'm assuming that you have a battery with some sort of BMS, and it's connected to the inverter via a suitable cable, and that's why the battery icon is flashing.

28.0 V would be 3.5 VPC if it's an 8S LFP battery (i.e. 8 Lithium Ferrous Phosphate battery cells in series means an average of 3.5 V per cell). This is consistent with a full battery. The 1 amp of current is inconsequential.

So I'm not seeing an actual problem here. If there is, please explain the problem in more detail.

yes, the is a BMS , it is a lithium battery, the problem is : input PV 855W , output Power 737 , and there is current from battery , is there an update to solve the wrong readings ???

49 minutes ago, alaba 678 said:

yes, the is a BMS , it is a lithium battery, the problem is : input PV 855W , output Power 737 , and there is current from battery , is there an update to solve the wrong readings ???

If I look at the 2nd picture with battery at 28V and no battery charging means the battery is full and all 754W is used towards the load of about 25-50%.

11 minutes ago, Scorp007 said:

If I look at the 2nd picture with battery at 28V and no battery charging means the battery is full and all 754W is used towards the load of about 25-50%.

i know , if the battery is full charge , and load wattage is less then then the PV power , why it is show me there is current from battery to load

 

because your inverter consumes about 60w. and the "float" to the battery is also about 60w. there is your 120w difference. 

 

your PV will never bypass the battery. 

 

there is nothing wrong with your display or the way its working. 

i think you are misunderstanding the screens

 

 

 

Also, there are all sorts of estimations going on, as not everything is measured. Battery current, for example, is calculated, and they don't bother rounding with their divisions. They often work in whole battery amps as well. So it's easy to be off by 1 or 2 amps.

On 2023/07/15 at 5:49 PM, Flouw said:

because your inverter consumes about 60w. and the "float" to the battery is also about 60w. there is your 120w difference. 

 

your PV will never bypass the battery. 

 

there is nothing wrong with your display or the way its working. 

i think you are misunderstanding the screens

 

 

 

You didn't understand what I meant. If the panels are enough, why does it appear to me that there are clouds of batteries to carry? Watch the pictures carefully, my friend

On 2023/07/15 at 6:19 PM, Coulomb said:

Also, there are all sorts of estimations going on, as not everything is measured. Battery current, for example, is calculated, and they don't bother rounding with their divisions. They often work in whole battery amps as well. So it's easy to be off by 1 or 2 amps.

It means a misreading, is that what you mean? The battery is lithium, and there is no current for the float, so de jure there are errors in the readings, and I am looking for an update to solve this problem

13 hours ago, alaba 678 said:

It means a misreading, is that what you mean?

I mean it's not possible to be very accurate with the hardware it's working with.

Quote

The battery is lithium, and there is no current for the float,

Lithium batteries do draw a small current to keep them at float voltage. Especially the high float voltage that manufacturers recommend, and the BMS probably enforces.

Quote

so de jure there are errors in the readings, and I am looking for an update to solve this problem

Those "errors" are slight, and an update will not reduce them.

4 hours ago, Coulomb said:

I mean it's not possible to be very accurate with the hardware it's working with.

Lithium batteries do draw a small current to keep them at float voltage. Especially the high float voltage that manufacturers recommend, and the BMS probably enforces.

Those "errors" are slight, and an update will not reduce them.

My friend, first, lithium batteries do not draw any current at the stage of fullness, unlike liquid batteries, 
which depend on the basis of their work on the chemical reaction, and to keep the battery active, it draws a very weak
 current after the charging stage. Secondly, the problem that occurs to me is the exact opposite of that. It is not the battery 
that consumes energy. But the batteries provide power for the loads, although there is enough power from the panels

16 minutes ago, alaba 678 said:

It is not the battery that consumes energy. But the batteries provide power for the loads, although there is enough power from the panels

Ok, but I'm saying that the battery current will be low (a few amps at most), and there isn't hardware to measure the battery current directly. So the firmware has to estimate that current, based on measurements it has available, and guessing efficiencies and the like. The result is that the firmware does not and can not know the exact battery current, and at these low currents, it doesn't even know which direction battery current is flowing.

So I'm pretty sure that you won't be able to fix this minor problem with a firmware update. The latest firmware I have for this model is 41.17 from late 2020.

18 hours ago, alaba 678 said:

You didn't understand what I meant. If the panels are enough, why does it appear to me that there are clouds of batteries to carry? Watch the pictures carefully, my friend

according to the photos you posted. 

the one where it shows 28v, and 737w Output. 

that is not your batteries output. but the inverter output. 

PV supplies the DC to DC converter, DC does to the batteries, and from there it supplies the DC to AC inverter. 

the one picture shows 1A, this could very well be how much is drawn from the battery, and this is not constant. 

 

i have similar display, and hooked up to various monitoring items. and been staring at them for weeks now to see the trend and understand how they function and react. 

if and when the PV panels produce for instance 800w, and your load is 800w. (for arguments sake, knowing it wont be an exact match as there is losses)

and your load drops to 300w. then the excess amps runs into the battery until the MPPT can respond and reduce its output (raise the volts and reduce the amps). that will let your battery volts run up slightly, and since you are on the higher end of the voltage curve of lithium, it ramps the volts rather quickly. 

- my inverter then draws current from the battery to reduce the voltage back to the set float/charge setting it is currently in and settles. hence why you will get amperage draws from the battery, even though its fully charged, and the PV is providing more than enough. this is only until the voltage settles again. 

 

so what i am saying, you are misunderstanding the display.  

2 hours ago, Coulomb said:

Ok, but I'm saying that the battery current will be low (a few amps at most), and there isn't hardware to measure the battery current directly. So the firmware has to estimate that current, based on measurements it has available, and guessing efficiencies and the like. The result is that the firmware does not and can not know the exact battery current, and at these low currents, it doesn't even know which direction battery current is flowing.

So I'm pretty sure that you won't be able to fix this minor problem with a firmware update. The latest firmware I have for this model is 41.17 from late 2020.

first ,thank you to your help 

did you do some like this update (41.17) what is your opinian about it??

1 hour ago, Flouw said:

according to the photos you posted. 

the one where it shows 28v, and 737w Output. 

that is not your batteries output. but the inverter output. 

PV supplies the DC to DC converter, DC does to the batteries, and from there it supplies the DC to AC inverter. 

the one picture shows 1A, this could very well be how much is drawn from the battery, and this is not constant. 

 

i have similar display, and hooked up to various monitoring items. and been staring at them for weeks now to see the trend and understand how they function and react. 

if and when the PV panels produce for instance 800w, and your load is 800w. (for arguments sake, knowing it wont be an exact match as there is losses)

and your load drops to 300w. then the excess amps runs into the battery until the MPPT can respond and reduce its output (raise the volts and reduce the amps). that will let your battery volts run up slightly, and since you are on the higher end of the voltage curve of lithium, it ramps the volts rather quickly. 

- my inverter then draws current from the battery to reduce the voltage back to the set float/charge setting it is currently in and settles. hence why you will get amperage draws from the battery, even though its fully charged, and the PV is providing more than enough. this is only until the voltage settles again. 

 

so what i am saying, you are misunderstanding the display.  

You say that the principle of the Mppt solar charger algorithm is that it withdraws from the battery 
to raise its voltage again?? Can you mention or specify any algorithm from Mppt that does this

1 hour ago, Flouw said:

according to the photos you posted. 

the one where it shows 28v, and 737w Output. 

that is not your batteries output. but the inverter output. 

PV supplies the DC to DC converter, DC does to the batteries, and from there it supplies the DC to AC inverter. 

the one picture shows 1A, this could very well be how much is drawn from the battery, and this is not constant. 

 

i have similar display, and hooked up to various monitoring items. and been staring at them for weeks now to see the trend and understand how they function and react. 

if and when the PV panels produce for instance 800w, and your load is 800w. (for arguments sake, knowing it wont be an exact match as there is losses)

and your load drops to 300w. then the excess amps runs into the battery until the MPPT can respond and reduce its output (raise the volts and reduce the amps). that will let your battery volts run up slightly, and since you are on the higher end of the voltage curve of lithium, it ramps the volts rather quickly. 

- my inverter then draws current from the battery to reduce the voltage back to the set float/charge setting it is currently in and settles. hence why you will get amperage draws from the battery, even though its fully charged, and the PV is providing more than enough. this is only until the voltage settles again. 

 

so what i am saying, you are misunderstanding the display.  

In addition to the presence of a cable to communicate with the BMS battery, and therefore it is supposed 
to give information from the battery, and given the battery screen, there is no current consumption from the battery

15 minutes ago, alaba 678 said:

You say that the principle of the Mppt solar charger algorithm is that it withdraws from the battery 
to raise its voltage again?? Can you mention or specify any algorithm from Mppt that does this

 

no. the Mppt does not draw anything from the battery. 

the Mppt takes a little time to react to load changes, and therefore uses the battery as a "cushion" for a second. 

so when the loads reduce, the Mppt might run the battery voltage past set value until it can react and stabalise. To control the voltage, it will consume a little from the battery again after load is settled to get the voltage back to set value. ive seen up to 11amp drawn from the battery after the voltage run up when i disconnect heavy loads. this is only for few seconds. 

 

the consumption from battery is indicated in A. the first photo you posted shows that 1A is being drawn from the battery. the display being "dumb", does not show decimals, and could in fact be 0.6amp being drawn, but the display will round it to 1A. and this could very well be the inverter trying to maintain the set voltage. 

 

Photo 01 - Battery Voltage, and consumption of 1 amp, that could be anything from 0.4 amp to 1.4amp, rounding off)

Photo 02 - Battery Voltage and inverter output. (whether the power comes from the PV panels, or the battery, that measurement is made on the DC to AC Inverter)

Photo 03 - isn't this the same screen as nr 02? load changed slightly since previous photo. 

Photo 04 - PV power input and AC voltage output.

Photo 05 - AC input frequency, and voltage output. 

 

 

i hope this makes more sense now. 

On 2023/07/15 at 3:37 PM, alaba 678 said:

i know , if the battery is full charge , and load wattage is less then then the PV power , why it is show me there is current from battery to load

 

If we make a u turn look back at picture 2 and you will see there is no power from battery as per the picture showing the flow of power. 

21 hours ago, alaba 678 said:

this update (41.17) what is your opinion about it??

I have no special opinion on it; I only mention the version number in case it's more recent than what you already have.

On 2023/07/15 at 3:30 PM, alaba 678 said:

yes, the is a BMS , it is a lithium battery, the problem is : input PV 855W , output Power 737 , and there is current from battery , is there an update to solve the wrong readings ???

@alaba 678 What make/model is your lithium battery?