Victron start shunt is not so smart

[Miketcq8]

Victron Smart shunt reporting 10,9% SoC, yet the batteries are at 27,58V.

Clearly something is wrong and I'm at a loss. Yes, the last 4 days have been rainy here in Finland, so much for Summer, the batteries are not getting topped up but It should cover the load of the fridge. Should I ignore the Low SoC warning given the batteries are at 27,6V?

Background:
300Ah LifePo4 batteries, wired to the Victron shunt then to a busbar. The solar and the inverter feed to the busbar.
There is a new 5000W inverter running a 220V fridge. This is a new setup and have been running for two months with only and over voltage error (reported and fixed in an earlier post) This is an off grid Cottage, currently I'm not at the cottage, I'm back next week Wednesday.

---

The photos taken below juts to show the strings, were taken last Wednesday.

---

The VRM image below was taken today. This is where I get the quoted 10,9% SOC.

 

[Brucey]

Victron Smart shunt reporting 10,9% SoC, yet the batteries are at 27,58V.

Clearly something is wrong and I'm at a loss. Yes, the last 4 days have been rainy here in Finland, so much for Summer, the batteries are not getting topped up but It should cover the load of the fridge. Should I ignore the Low SoC warning given the batteries are at 27,6V?

Background:
300Ah LifePo4 batteries, wired to the Victron shunt then to a busbar. The solar and the inverter feed to the busbar.
There is a new 5000W inverter running a 220V fridge. This is a new setup and have been running for two months with only and over voltage error (reported and fixed in an earlier post) This is an off grid Cottage, currently I'm not at the cottage, I'm back next week Wednesday.

---

The photos taken below juts to show the strings, were taken last Wednesday.

View attachment 308452View attachment 308453

---

The VRM image below was taken today. This is where I get the quoted 10,9% SOC.
View attachment 308443

Adjust your peukert exponent from 1.25 to 1.05 or less. 1.25 is for lead acid.

 

[Brucey]

I use 1.01:

M

Thread 'peukert Exponent vs SOC'

Feb 6, 2023

I almost understand peukert exponent.
I do do understand SOC.
I don't understand why when I changed the peukert exponent from factory of 1.25 to recommend 1.01 in my Victron Smart Shunt it lowered the SOC from 75% to 30%.
I can move it up or down with the same results using different values.

400 ah Amperetime Battery
Victron Smart Shunt
Victron Smart Solar Controllers

I just don't understand the correlation.
Thanks Guys.

• Mike Wilson
• Replies: 23
• Forum: DIY Solar General Discussion

 

[ricardocello]

Papa Smurf Advice on SmartShunt is Here:

Thread 'Victron Shunt Settings (concept and some settings may apply to others)'

Jan 8, 2025

Misconfiguring a shunt is the most common reason for inaccuracy. Failure to regularly sync is another.

The shunt is a monitoring device. It can share it's measurements with other components in a Victron system, but it does not control any of the other components.

It works by counting Ah in and out of a battery, comparing it to the programmed capacity and computing the % charge. It is critical that it is installed correctly such that ALL current in and out of the battery passes through the shunt.

It's not perfect. It must be synchronized to 100% during a full charge on a regular basis...

• sunshine_eggo
• Replies: 51
• Forum: General Battery Discussion

• 
• 

 

[HRTKD]

Definitely read the Victron Shunt Settings thread.

What are the settings for your solar charge controller?

 

[Miketcq8]

Adjust your peukert exponent from 1.25 to 1.05 or less. 1.25 is for lead acid.

Thanks for the education. Made a note to fix it on Wednesday

 

[Miketcq8]

Definitely read the Victron Shunt Settings thread.

What are the settings for your solar charge controller?

Attached...

 

[mikefitz]

Attached

Change absorbtion to 28.4 volts, float to 27.0 volts in the charger/s.
In the shunt change, 'charged voltage' to 28.2 volts, ( 0.2 volts lower than absorbtion), charge efficiency 99%, Peukerts 1.05, tail current 4%, detection time 3 minutes

 

[Miketcq8]

Adjust your peukert exponent from 1.25 to 1.05 or less. 1.25 is for lead acid.

Thanks for the information

 

[Miketcq8]

Change absorbtion to 28.4 volts, float to 27.0 volts in the charger/s.
In the shunt change, 'charged voltage' to 28.2 volts, ( 0.2 volts lower than absorbtion), charge efficiency 99%, Peukerts 1.05, tail current 4%, detection time 3 minutes

I'll try these settings, thanks for the input.

 

[Miketcq8]

I'll try these settings, thanks for the input.

I'm at a loss... I changed the settings on the shunt and MPPT yet the SOC still drops down and ignores the Solar input... Any chance that this shunt is faulty and I should approach Victron on a warrantee claim?

 

[Brucey]

I'm at a loss... I changed the settings on the shunt and MPPT yet the SOC still drops down and ignores the Solar input... Any chance that this shunt is faulty and I should approach Victron on a warrantee claim?

Is the mppt negative connected to the shunt load side?

 

[Miketcq8]

Is the mppt negative connected to the shunt load side?

I'm not sure I understand your question, but the shunt is connected as follows: Battery - Shunt - busbar - loads and MPPT.
The shunt is marked "to Battery Minus" and "to System Minus." The batteries are on the battery side connected at a busbar.

See below:
Sorry about the photos, it's all I have from the inputs!

The shunt worked fine at the end of last summer. Earlier this summer there was a software update with new functionality.

 

[SouthernSolar]

Under setting misc, make sure you’re in battery monitor mode

 

[outboard1196]

I'm at a loss... I changed the settings on the shunt and MPPT yet the SOC still drops down and ignores the Solar input... Any chance that this shunt is faulty and I should approach Victron on a warrantee claim?

Is the battery voltage correct, just soc is wrong?
Also under shunt settings, SOC reset should be changed to keep SOC.

 

[740GLE]

I'm at a loss... I changed the settings on the shunt and MPPT yet the SOC still drops down and ignores the Solar input... Any chance that this shunt is faulty and I should approach Victron on a warrantee claim?

The shunt will just track current in and out of the battery, if you have constant loads, those loads will be sucked off and not shown on the shunt.

15a from the SCC
5a to load (inverter or what not)
only 10a will be going into the battery and shown on the shunt as current flow.

If your load is exceeding the SCC input, the battery will be supplying the load and SOC will go down.

Simple KCL math will maths it out.

If you isolate all loads so it’s just SCC and shunt, and the currents don’t add up then yeah something is wrong with the shunt.

 

[Miketcq8]

Under setting misc, make sure you’re in battery monitor modeView attachment 312739

This is how it's setup. A battery monitor.

 

[Miketcq8]

The shunt will just track current in and out of the battery, if you have constant loads, those loads will be sucked off and not shown on the shunt.

15a from the SCC
5a to load (inverter or what not)
only 10a will be going into the battery and shown on the shunt as current flow.

If your load is exceeding the SCC input, the battery will be supplying the load and SOC will go down.

Simple KCL math will maths it out.

If you isolate all loads so it’s just SCC and shunt, and the currents don’t add up then yeah something is wrong with the shunt.

The battery voltage is full around 27.8V in a 24 V system.... the solar does not put any more into the batteries.... The shunt shows 0,0% SOC after 10 days summer sunny days. By +-9:30 the batteries are full .

 

[outboard1196]

The battery voltage is full around 27.8V in a 24 V system.... the solar does not put any more into the batteries.... The shunt shows 0,0% SOC after 10 days summer sunny days. By +-9:30 the batteries are full .

Can you screenshot the shunt settings page?
Almost sounds like either the shunt is reversed (via settings) or wired wrong.

 

[Zwy]

Battery SOC on Reset needs to be changed to Keep SOC

I ran the house shunt for a year with Set To 100% It never agreed with the Batrium shuntmon if any extended period of not actually hitting full SOC was reached. The problem with that setting is when the high battery voltage of the day is reached, the shunt will calculate off that voltage.

I use Peukert of 1.03 on both Victron shunts. You might have to disconnect cables and perform a Zero Current Calibration.

The battery voltage is full around 27.8V in a 24 V system.... the solar does not put any more into the batteries.... The shunt shows 0,0% SOC after 10 days summer sunny days. By +-9:30 the batteries are full .

At 27.8V, it will need extended absorption time to get cells to full SOC. I prefer using 3.50V per cell and shorter absorption time.

 

[740GLE]

Can you screenshot the shunt settings page?
Almost sounds like either the shunt is reversed (via settings) or wired wrong.

First post

But he did update settings.

He also showed the SCC outputting 14a and the shunt charging the battery at 11a so there is some load mixed in.

 

[outboard1196]

First post

But he did update settings.

Yes, want to see current settings.

 

[outboard1196]

@Miketcq8
Remove all conductors from system side of shunt, current should read 0 A if it doesn't you need to perform zero current calibration.

 

[Miketcq8]

Can you screenshot the shunt settings page?
Almost sounds like either the shunt is reversed (via settings) or wired wrong.

There are photos above of the (1) settings (2) how its wired...

 

[Miketcq8]

Battery SOC on Reset needs to be changed to Keep SOC

I ran the house shunt for a year with Set To 100% It never agreed with the Batrium shuntmon if any extended period of not actually hitting full SOC was reached. The problem with that setting is when the high battery voltage of the day is reached, the shunt will calculate off that voltage.

I use Peukert of 1.03 on both Victron shunts. You might have to disconnect cables and perform a Zero Current Calibration.


At 27.8V, it will need extended absorption time to get cells to full SOC. I prefer using 3.50V per cell and shorter absorption time.

SOC has read all the way down to 0% now.... and it's been like this for summer with the battery holding between 26v to 27v depending on the time of the day.. Peukert of 1.05 as advised by others in this post., but the SOC keeps going down and has remained at ZERO for a few days now.