VictronConnect / DC Home Accuracy Issues

[phoenixmoon]

I have a 24V system with 1500W of solar panels wired in series-parallel with 800AH of LI battery.

The 24V system is new, I rewired my 12V system.

I'm not getting accurate readings from either VC or DCH.

Example: VC currently says that I have 100% SOC but my voltage reads as 12.11 (8.3A, 101W)

DC Home says I'm at 82% SOC (30.6 Solar Volts, 4.28 Solar Amps, 131 Solar Watts)

So it's kind of a two part question:

1) How do I get VC to update so that it's reading me my actual voltage for a 24V system?
2) Why the discrepancy between the amps on the two apps?

 

[sunshine_eggo]

I have a 24V system with 1500W of solar panels wired in series-parallel with 800AH of LI battery.

The 24V system is new, I rewired my 12V system.

I'm not getting accurate readings from either VC or DCH.

Example: VC currently says that I have 100% SOC but my voltage reads as 12.11 (8.3A, 101W)

DC Home says I'm at 82% SOC (30.6 Solar Volts, 4.28 Solar Amps, 131 Solar Watts)

So it's kind of a two part question:

1) How do I get VC to update so that it's reading me my actual voltage for a 24V system?
2) Why the discrepancy between the amps on the two apps?

Victron Connect is an application. It is not a piece of hardware. I assume that you have a smartshunt or BMV? When you disconnect a Victron shunt, you have the following options:

Display 100% when powered on.
Display last known SoC when powered on (smart shunt and BMV-712 only)
Display "--" indicating an unknown SoC.

You likely are configured for the first option.

1) Confirm the shunt settings are correct and fully charge the battery triggering a sync and/or guesstimate the SoC and set it manually (it is VERY low @ 12.11V).
2) I don't know what DCH is or how it gets its information. The shunt directly measures the NET current flow to and from the battery. VC reports what the shunt measures. If DCH isn't doing the same thing, then it won't read the same.

 

[phoenixmoon]

How do I confirm that the shunt settings are correct?

Weirdly, VC now says that I'm at 89% and running -2.54A and -33W while DCH says I'm at 100% SOC and the batteries are running at boost.

 

[phoenixmoon]

Victron Connect is an application. It is not a piece of hardware. I assume that you have a smartshunt or BMV? When you disconnect a Victron shunt, you have the following options:

Display 100% when powered on.
Display last known SoC when powered on (smart shunt and BMV-712 only)
Display "--" indicating an unknown SoC.

You likely are configured for the first option.

1) Confirm the shunt settings are correct and fully charge the battery triggering a sync and/or guesstimate the SoC and set it manually (it is VERY low @ 12.11V).
2) I don't know what DCH is or how it gets its information. The shunt directly measures the NET current flow to and from the battery. VC reports what the shunt measures. If DCH isn't doing the same thing, then it won't read the same.

How do I confirm that the shunt settings are correct?

Weirdly, VC now says that I'm at 89% and running -2.54A and -33W while DCH says I'm at 100% SOC and the batteries are running at boost.

 

[sunshine_eggo]

How do I confirm that the shunt settings are correct?

Screencap it and post it.

Charged voltage should be 0.2V below absorption.
Tail current should be 6%
Peukert 1.05
Charge efficiency 99%

How do I confirm that the shunt settings are correct?

Weirdly, VC now says that I'm at 89% and running -2.54A and -33W

There is a net outflow of 2.54A and 33W, i.e., the battery is discharging. It has discharged 11% since the discharge began.

while DCH says I'm at 100% SOC and the batteries are running at boost.

What is DCH? Be VERY specific.

If DCH is a charge controller, it's reporting what it outputs, not what goes into or out of the battery. Some may go to battery and some may go to loads. The Shunt ONLY shows what is going in or out of the battery.

If DCH is a charge controller, it's SoC value is almost certainly voltage based, and it should be ignored at all times as it will ALWAYS be wrong unless it just happens to read what the shunt says once the shunt has synched and is tracking correctly.

 

[phoenixmoon]

Screencap it and post it.

Charged voltage should be 0.2V below absorption.
Tail current should be 6%
Peukert 1.05
Charge efficiency 99%



There is a net outflow of 2.54A and 33W, i.e., the battery is discharging. It has discharged 11% since the discharge began.



What is DCH? Be VERY specific.

If DCH is a charge controller, it's reporting what it outputs, not what goes into or out of the battery. Some may go to battery and some may go to loads. The Shunt ONLY shows what is going in or out of the battery.

If DCH is a charge controller, it's SoC value is almost certainly voltage based, and it should be ignored at all times as it will ALWAYS be wrong unless it just happens to read what the shunt says once the shunt has synched and is tracking correctly.

DCH = "DC Home," yes it reads the charge controller.

I don't know why the battery would have discharged by 11 percent, the sun was still high in the sky and I've been charging all day running very little.

I don't know what "shunt settings" are or how to find them.

 

[sunshine_eggo]

DCH = "DC Home," yes it reads the charge controller.

I gleaned what the abbreviation meant from the subject line.

Not specific enough. What is it and what charge controller?

I don't know why the battery would have discharged by 11 percent, the sun was still high in the sky and I've been charging all day running very little.

Installation issue.

Settings issue.

Expectations/perception issue.

I don't know what "shunt settings" are or how to find them.

Click the settings gear in VC. You (or someone) should have already opened that and programmed it for your battery.

 

[sunshine_eggo]

Oh... DC Home is the Renogy app. No wonder I don't know anything about it. I avoid Renogy like the plague.

Anyway, so, you are looking at two different values:

VC: net current in and out of the battery.
DCH: current produced by the charge controller.

They will only be the same if there are absolutely, positively no loads of any kind on the battery and even then, they are subject to accuracy and calibration issues. Literally, the battery is ONLY connected to the MPPT.

The charge controller reported SoC should be completely ignored. It is voltage based and is worthless in almost all cases. It will ALWAYS be wrong unless it just happens to read what the shunt says once the shunt has synched and is tracking correctly.

I can't emphasize this enough... The Renogy reported SoC is beyond worthless. You should pretend the value doesn't exist.

 

[phoenixmoon]

I gleaned what the abbreviation meant from the subject line.

Not specific enough. What is it and what charge controller?

I have a Rover 100A MPPT charge controller.

"The DC Home app is made specially for the off-grid community to monitor your Renogy powered solar solutions, share your DIY solutions in the community, and learn more about the solar energy from Renogy users worldwide."

Installation issue.

Settings issue.

Expectations/perception issue.



Click the settings gear in VC. You (or someone) should have already opened that and programmed it for your battery.

I think we probably start with the settings issue, though we did recently have some work done on the solar to change from a 12V system to a 24V system and it's been giving funky readings ever since. Example: It showed that the batteries were draining pretty much all day, but I had basically nothing on, whereas before it would be giving "boost" type readings of minimal charge.

Here's the settings you asked for (I think?)

image0 hosted at ImgBB

Image image0 hosted in ImgBB

ibb.co

 

[sunshine_eggo]

I have a Rover 100A MPPT charge controller.

"The DC Home app is made specially for the off-grid community to monitor your Renogy powered solar solutions, share your DIY solutions in the community, and learn more about the solar energy from Renogy users worldwide."

I think we probably start with the settings issue, though we did recently have some work done on the solar to change from a 12V system to a 24V system and it's been giving funky readings ever since. Example: It showed that the batteries were draining pretty much all day, but I had basically nothing on, whereas before it would be giving "boost" type readings of minimal charge.

Here's the settings you asked for (I think?)

image0 hosted at ImgBB

Image image0 hosted in ImgBB

ibb.co

I'm assuming you have a smartshunt. It would be nice to know for certain. Mushroom theory isn't the best way to get answers.

The shunt is not programmed correctly. Per my two posts above, the charged voltage should be 0.2V below the Absorption (boost) voltage of the MPPT. It is set too low @ 26.4V and will trigger false sync with solar charging, i.e., it will read 100% prematurely. Tail current should be 6.00%. Discharge floor recommend at 20% - this just affects the "time to go" value. It's nice to know you have a little reserve when it says the battery will deplete in 10 hours.

You say 800Ah, but the shunt is programmed for 400Ah. Which is it? Make sure you're are properly adding Ah - many get it wrong. Can you describe the battery bank? e.g., two 400Ah 12V wired in series to make 24V is still only 400Ah, but two 400Ah 24V wired in parallel are 800Ah. 800Ah in 24V is a damn big battery.

The Battery SoC on reset "Set to 100%" is why the unit read 100% after it was disconnected. One of the options should be "Keep SoC" if you have smartshunt or BMV-712. If not, select "Clear" - that way you know the shunt has lost power and doesn't know the SoC rather than think you have.

Given that you have had work done, it is entirely possible that something has been wired incorrectly. The shunt has two terminals on it. ONE terminal goes to the primary (-) battery terminal. EVERYTHING else goes to the other terminal on the shunt. You must not connect anything directly to the battery - all loads and charging MUST pass through the shunt, or the shunt will always be wrong.

Can you include a picture of the shunt and the main negative battery terminal?

 

[phoenixmoon]

I'm assuming you have a smartshunt. It would be nice to know for certain. Mushroom theory isn't the best way to get answers.

The shunt is not programmed correctly. Per my two posts above, the charged voltage should be 0.2V below the Absorption (boost) voltage of the MPPT. It is set too low @ 26.4V and will trigger false sync with solar charging, i.e., it will read 100% prematurely. Tail current should be 6.00%. Discharge floor recommend at 20% - this just affects the "time to go" value. It's nice to know you have a little reserve when it says the battery will deplete in 10 hours.

You say 800Ah, but the shunt is programmed for 400Ah. Which is it? Make sure you're are properly adding Ah - many get it wrong. Can you describe the battery bank? e.g., two 400Ah 12V wired in series to make 24V is still only 400Ah, but two 400Ah 24V wired in parallel are 800Ah. 800Ah in 24V is a damn big battery.

The Battery SoC on reset "Set to 100%" is why the unit read 100% after it was disconnected. One of the options should be "Keep SoC" if you have smartshunt or BMV-712. If not, select "Clear" - that way you know the shunt has lost power and doesn't know the SoC rather than think you have.

Given that you have had work done, it is entirely possible that something has been wired incorrectly. The shunt has two terminals on it. ONE terminal goes to the primary (-) battery terminal. EVERYTHING else goes to the other terminal on the shunt. You must not connect anything directly to the battery - all loads and charging MUST pass through the shunt, or the shunt will always be wrong.

Can you include a picture of the shunt and the main negative battery terminal?

What is the absorption voltage of the MPPT? How would I find this?

Another thing I noticed is that even when I leave the system all day with no inverter on just running my propane fridge and other 12V stuff it only charges up to 99% on VC.

I have 4x12V 200AH LI batteries wired for a 24V system. I'm posting an image of my setup below.

image0-1 hosted at ImgBB

Image image0-1 hosted in ImgBB

ibb.co

image1 hosted at ImgBB

Image image1 hosted in ImgBB

ibb.co

 

[sunshine_eggo]

What is the absorption voltage of the MPPT? How would I find this?

The Renogy MPPT must have a setup screen. I recommend you seek the manual for your specific unit online and determine the charge parameters.

Another thing I noticed is that even when I leave the system all day with no inverter on just running my propane fridge and other 12V stuff it only charges up to 99% on VC.

Your charge parameters do not permit the battery to be fully charged and/or the shunt is not configured correctly (we've established this part for sure).

How is the 12V stuff being powered by a 24V system? If you are pulling 12V from one of your 12V batteries in the 24V battery bank, you must stop immediately! This will not work!

I have 4x12V 200AH LI batteries wired for a 24V system. I'm posting an image of my setup below.

image0-1 hosted at ImgBB

Image image0-1 hosted in ImgBB

ibb.co

image1 hosted at ImgBB

Image image1 hosted in ImgBB

ibb.co

Okay, so you have a 2S2P (2 in series, 2 in parallel) battery bank comprised of 4X 12V 200Ah batteries. This is a 400Ah 24V battery. The shunt is programmed correctly for battery capacity.

Unfortunately, this isn't tremendously helpful. I can't tell what's what.



The batteries on the right are clearly in series for 24V, but unfortunately, I can't tell anything meaningful about the two batteries on the left side. Additionally, you appear to have incorrectly wired your bank. You appear to have both of your primary (+) and (-) terminals drawing from the batteries on the left. That will result in uneven load on the battery groups. It doesn't matter which, but one main terminal should be on the left group and the other on the right group. Again, the shunt must be the ONLY thing connected to the main (-) terminal.

 

[phoenixmoon]

The Renogy MPPT must have a setup screen. I recommend you seek the manual for your specific unit online and determine the charge parameters.



Your charge parameters do not permit the battery to be fully charged and/or the shunt is not configured correctly (we've established this part for sure).

How is the 12V stuff being powered by a 24V system? If you are pulling 12V from one of your 12V batteries in the 24V battery bank, you must stop immediately! This will not work!



Okay, so you have a 2S2P (2 in series, 2 in parallel) battery bank comprised of 4X 12V 200Ah batteries. This is a 400Ah 24V battery. The shunt is programmed correctly for battery capacity.

Unfortunately, this isn't tremendously helpful. I can't tell what's what.

View attachment 153671

The batteries on the right are clearly in series for 24V, but unfortunately, I can't tell anything meaningful about the two batteries on the left side. Additionally, you appear to have incorrectly wired your bank. You appear to have both of your primary (+) and (-) terminals drawing from the batteries on the left. That will result in uneven load on the battery groups. It doesn't matter which, but one main terminal should be on the left group and the other on the right group. Again, the shunt must be the ONLY thing connected to the main (-) terminal.

Will contact Renogy about the programming issue, the manual wasn't helpful.

If I'm understanding correctly, the issue you are describing with regard to the left image is that there are two cables connected to one of the terminals and there should only be one. I should instead connect one of those cables to one battery and the other to the other. Is this right?

Also, how do I know which cable is the shunt? Please forgive my ignorance, I am extremely new at this and not the handiest guy on earth.

Does this image help more?

image0-2 hosted at ImgBB

Image image0-2 hosted in ImgBB

ibb.co

 

[sunshine_eggo]

You did not answer the question:

HOW ARE YOU POWERING YOUR 12V LOADS? Do you have a separate 12V system, or are you connecting to one of the 12V that makes up your 24V bank?

If you are pulling 12V from one of the batteries in the 24V bank, you must stop immediately.

Will contact Renogy about the programming issue, the manual wasn't helpful.

Please link me the manual. Renogy is not well known for their support or command of the English language. I can probably help faster.

If I'm understanding correctly, the issue you are describing with regard to the left image is that there are two cables connected to one of the terminals and there should only be one. I should instead connect one of those cables to one battery and the other to the other. Is this right?

I can't say yet.

Also, how do I know which cable is the shunt? Please forgive my ignorance, I am extremely new at this and not the handiest guy on earth.

I have identified the shunt.

Does this image help more?

image0-2 hosted at ImgBB

Image image0-2 hosted in ImgBB

ibb.co

Please tell me where each of the 8 cables go:



"phoenixmoon" in AZ implies you're in the Phoenix area. Is that correct?

I'm in Mesa.

Conceptually, this is what your battery wiring should look like:

 

[phoenixmoon]

You did not answer the question:

HOW ARE YOU POWERING YOUR 12V LOADS? Do you have a separate 12V system, or are you connecting to one of the 12V that makes up your 24V bank?

If you are pulling 12V from one of the batteries in the 24V bank, you must stop immediately.



Please link me the manual. Renogy is not well known for their support or command of the English language. I can probably help faster.



I can't say yet.



I have identified the shunt.



Please tell me where each of the 8 cables go:

View attachment 153752

"phoenixmoon" in AZ implies you're in the Phoenix area. Is that correct?

I'm in Mesa.

Conceptually, this is what your battery wiring should look like:

View attachment 153755

I think I'm doing the thing I'm not supposed to be doing, but unsure how to fix it. I texted the guy who rewired my system. Will let you know. Ditto on identifying where the wires go, because I'm guessing you don't want to hear "into the wall."

Manual:

https://pdf.lowes.com/productdocuments/b4162c3b-5227-4327-a96f-220e132ec462/12051815.pdf

I'm in Mohave County, Arizona between Havasu and Kingman.

 

[sunshine_eggo]

I think I'm doing the thing I'm not supposed to be doing, but unsure how to fix it.

Get a 24V to 12V converter. It takes the 24V and steps it down to 12V.

Get a voltmeter and measure all four individual 12V. Let me know what they are.

I texted the guy who rewired my system. Will let you know. Ditto on identifying where the wires go, because I'm guessing you don't want to hear "into the wall."

LOL... I appreciate your honesty.

Manual:

https://pdf.lowes.com/productdocuments/b4162c3b-5227-4327-a96f-220e132ec462/12051815.pdf

I'm in Mohave County, Arizona between Havasu and Kingman.

Gotcha. Back when I was young and foolish(er), I bought 1.25 acres in Mohave county on the way to the Skywalk just north of Diamond Bar Rd. I'm just paying taxes on it waiting for it to take off...



Gotta be worth 10X what I paid now that the road is paved, no?

No.

Do this:



Down arrow to #2, Parameter set and select OK:



Let me know the values for:

2:
3:
6:
7:
8:
13:
14:
16:

 

[phoenixmoon]

Get a 24V to 12V converter. It takes the 24V and steps it down to 12V.

Get a voltmeter and measure all four individual 12V. Let me know what they are.



LOL... I appreciate your honesty.



Gotcha. Back when I was young and foolish(er), I bought 1.25 acres in Mohave county on the way to the Skywalk just north of Diamond Bar Rd. I'm just paying taxes on it waiting for it to take off...

View attachment 153763

Gotta be worth 10X what I paid now that the road is paved, no?

No.

Do this:

View attachment 153765

Down arrow to #2, Parameter set and select OK:

View attachment 153766

Let me know the values for:

2:
3:
6:
7:
8:
13:
14:
16:

Yeah, I am a super novice at all of this and not the handiest guy in the world anyway. My father was a Boston Ironworker. Precisely zero rubbed off. Just got mom's useless bookworm shit.

I got five acres I live on and 40 I'm selling because of the divorce. It's got a house. Wanna buy it? Eh? Eh?

Would this converter work?

https://www.amazon.com/EPBOWPT-Converter-Regulator-Voltage-Transformer/dp/B07V6X6L89/ref=sr_1_3?keywords=24V+to+12V+Converter&sr=8-3

Here are those values:

2: LI
3: 400
6: 14.4
7: 14.4
8: 14.4
13: 0
14: 0
16: -0mV/C/2V

 

[sunshine_eggo]

Yeah, I am a super novice at all of this and not the handiest guy in the world anyway. My father was a Boston Ironworker. Precisely zero rubbed off. Just got mom's useless bookworm shit.

I got five acres I live on and 40 I'm selling because of the divorce. It's got a house. Wanna buy it? Eh? Eh?

No thanks... we have 39 acres over in Apache county.

Congrats on the divorce. No matter what it feels like, nobody gets out of a good marriage, and you'll come out better off. My wife and I are both on our second and last marriage.

Would this converter work?

https://www.amazon.com/EPBOWPT-Converter-Regulator-Voltage-Transformer/dp/B07V6X6L89/ref=sr_1_3?keywords=24V+to+12V+Converter&sr=8-3

Conceptually, yes, but 10A is pretty low. Do you have any 12V electric motors like a slide or something like that? Most RVs have something around 50A of 12V + a battery to compensate for any surge.

This 30A is the lowest I would consider:

Amazon.com: DC 24v to DC 12v Step Down 30A 360W Heavy Duty Truck Car Power Supply Adapter Converter Reducer Regulator for Auto Car Truck Vehicle Boat Solar System etc.(DC15-40V Inputs): Home Audio & Theater

Amazon.com: DC 24v to DC 12v Step Down 30A 360W Heavy Duty Truck Car Power Supply Adapter Converter Reducer Regulator for Auto Car Truck Vehicle Boat Solar System etc.(DC15-40V Inputs): Home Audio & Theater

www.amazon.com

or this 40A:

https://www.amazon.com/uxcell-Converter-Regulator-Transformer-Waterproof/dp/B01LYK6G2Y

.

Here are those values:

2: LI
3: 400
6: 14.4
7: 14.4
8: 14.4
13: 0
14: 0
16: -0mV/C/2V

Hmmm... I'm guessing the charge controller hasn't been reprogrammed for 24V?

Does #1 Sys Batt Volt: say AUTO or 24V?

 

[phoenixmoon]

No thanks... we have 39 acres over in Apache county.

Congrats on the divorce. No matter what it feels like, nobody gets out of a good marriage, and you'll come out better off. My wife and I are both on our second and last marriage.




Conceptually, yes, but 10A is pretty low. Do you have any 12V electric motors like a slide or something like that? Most RVs have something around 50A of 12V + a battery to compensate for any surge.

This 30A is the lowest I would consider:

Amazon.com: DC 24v to DC 12v Step Down 30A 360W Heavy Duty Truck Car Power Supply Adapter Converter Reducer Regulator for Auto Car Truck Vehicle Boat Solar System etc.(DC15-40V Inputs): Home Audio & Theater

Amazon.com: DC 24v to DC 12v Step Down 30A 360W Heavy Duty Truck Car Power Supply Adapter Converter Reducer Regulator for Auto Car Truck Vehicle Boat Solar System etc.(DC15-40V Inputs): Home Audio & Theater

www.amazon.com

or this 40A:

https://www.amazon.com/uxcell-Converter-Regulator-Transformer-Waterproof/dp/B01LYK6G2Y

.


Hmmm... I'm guessing the charge controller hasn't been reprogrammed for 24V?

Does #1 Sys Batt Volt: say AUTO or 24V?

Yeah I'm not bummed about being divorced. Just in the middle of things and she's trying to take my kid away because she thinks this is California in 1981 and not Arizona in 2023.

I do have slides, so do I need a 50A stepdown? Is this a thing I can get at Home Depot or True Value?

Sys Batt Volt says 24V. VictronConnect still reads for a 12V system.

 

[sunshine_eggo]

Yeah I'm not bummed about being divorced. Just in the middle of things and she's trying to take my kid away because she thinks this is California in 1981 and not Arizona in 2023.

Good luck!

I do have slides, so do I need a 50A stepdown? Is this a thing I can get at Home Depot or True Value?

I really don't know. I know my slide is fused for 80A. In this case, it might make sense to get a small 12V battery and 24-13.8V converter that will float the 12V @ 13.8V:

https://www.amazon.com/Diann-Automatic-Converter-Regulator-Waterproof/dp/B0B6BPNKXT

The 12V battery would deal with the heavy loads, and the converter would replenish it and hold it at full charge. As long as you don't use more than 276W continuously 24/7, the converter should keep up.

What happened to the original converter that provided 12V from 120VAC input? Are you running an inverter? My preferred solution in this case is to leave the RV 12V system intact and power the AC-DC converter with the inverter. While this is inefficient, and it retains a bulky 12V, it simplifies things and provides a second layer of backup for your 12V items.

My off-grid setup terminates at a 50A RV power pedestal. Both of my 5th wheels plug in and run their 12V converters from AC. There have been times where my system is taken offline, but the trailers still have 12V power. One of the trailers has the DSL modem for internet powered directly by 12V, so it keeps my connection alive even if I lose AC power.

Sys Batt Volt says 24V.

Does the charge controller display 24V?

VictronConnect still reads for a 12V system.

The sense wire on the shunt is probably connected at the wrong location. It should be connected on the primary (+) terminal.


The sense wire 1
appears to be connected to location 2
should be connected to location 3

Note that you need to change the "Battery SoC on reset" from "Set to 100%" to "Keep SoC" as disconnecting this wire will cut power to the shunt and reset according to this setting.

Again, please, can you measure and report all 4 12V batteries with a voltmeter?

I've bolded questions in case they get overlooked in my blabberings.