How to Set Up a Shunt

Are you looking to take your off-grid solar system to the next level? One crucial component that you may want to consider adding to your setup is a battery shunt. Designed to measure the flow of energy in your battery system, these little devices can be a huge help in monitoring and optimising your energy. 

Whether you are a seasoned DIY enthusiast or just starting out, this step-by-step guide will walk you through a simple shunt installation. 

Additionally, we will take you through the key parameters you need to program to get a Victron Smart Shunt or Battery Monitor working in your system.

Installing a Shunt

Shunts are designed to be connected to the negative terminal of your battery and measure the energy flow throughout your system. Depending on the type of shunt or battery monitor, the data collected can then be used to determine the battery’s state of charge.

They can use this information to trigger certain actions within the system, automating some of the tasks that you might need to do to keep your battery charged or your system running. But, this is only possible if you install and program the shunt correctly.

Read More: Why shunts and battery monitors are critical to your off-grid system

Before You Install

Before installing a shunt, it’s important to ensure you have all the necessary tools and components you need to safely install your shunt.

A basic or standard shunt installation shouldn’t require too many tools or additional components. You’ll need a spanner for the bolts on the shunt and a spanner or socket wrench for the terminals on your battery. If you’re wiring up a new battery system, you might also need some cable to connect your components; we recommend pre-wired cable if your system design allows.

For more complex installations that include additional components, or if you’re adding a shunt to a pre-existing complex system, you might also need some good quality cable cutters and crimpers, cable lugs, and some heat-shrink tubing.

If your installation requires stripping and connecting cables, we recommend that you ask a qualified electrician to perform these procedures.

Before starting your installation, it is critical that you disconnect your battery from any live power source and ensure that the system is safe for you to begin.

The Basic Shunt Setup​

Every off-grid energy system is different, as it should be tailored to the individual energy needs of whatever it is powering. Because of this, the specific components and wiring of a system are never going to be exactly the same, but there are some basic rules to follow to get a system working properly.

When installing a shunt in your system, you need to ensure that the system’s energy flows through the shunt, otherwise, it won’t be able to read anything in the system. To achieve this, you need to make sure the components are connected correctly. Here are the basic connections you need:

• A cable connecting the negative terminal (‘Battery -’) on your battery to the ‘Battery Minus’ terminal on your shunt
• A cable connecting the ‘System Minus’ terminal on your shunt to the ‘Battery’ negative terminal on your charger
• A cable connecting the ‘Battery’ positive terminal on your charger to the positive terminal (‘Battery +’) on your battery
• A small cable connecting the ‘Battery’ positive terminal on the shunt to the positive terminal (‘Battery +’) on your battery

On a Victron shunt, the ‘Battery’ positive terminal is the “VBatt +”​​ terminal, and the small cable is provided with the shunt

Below, we have provided a basic diagram of a solar and battery system to showcase how these components need to be connected to work together. 

Programming a Victron Shunt

Once you have your shunt correctly connected to your system, it will need to be programmed so it can begin accurately monitoring the system. Almost all, if not every, shunt or battery monitor these days can be easily programmed via a compatible app on any smart device.

Below is a step-by-step guide to programming a Victron Smart Shunt. This process is the same for most of the Victron Battery Monitors as well. Other brands of shunt or battery monitor will have their own specific steps to go through, however, the parameters you need to set will be very similar.

1. Connect the Shunt to Your Phone

• Download the VictronConnect app
• In the app, find & select the shunt or monitor you have
• Enter the PIN found on the side of the shunt or monitor
• The shunt is now connected to your phone

2. Open the Settings Menu

Click  the small cog in the top left hand corner to open the settings menu.

3. Enter the ‘First Use Setup’ Parameters

• Enter your total battery bank capacity i.e. if you have 3x 200Ah batteries, the battery capacity would be 600Ah
• Enter your auxiliary input i.e. if you want to monitor your starter battery, this is where you can input that information

4. Now the Rest of the Settings Will Appear

Click on ‘Battery’ to open the battery settings menu. The battery capacity should already be set as that was programmed earlier.

5. Click on ‘Charged Voltage’ to open this setting

• This is the voltage at which the shunt recognises that the battery is fully charged. Once it reaches this voltage for a certain amount of time, the shunt declares the battery fully charged. What you should program your charged voltage to is dependent on the battery charger you are using. You will need to set it to 0.2V below the Float Voltage for your charger or 0.2V below the Absorption Voltage for your charger if you have solar in your system.
• Change the ‘Charged Voltage’ to the correct voltage and click OK.

6. Click on ‘Discharge Floor’ to open this setting

• The discharge floor helps the shunt determine how much of the battery’s capacity you want to use. The shunt can alert you when the battery is reaching this percentage of its capacity, so you can know to charge the battery again. For AGM or lead-acid batteries, you would set this to the default 50%. For lithium batteries, you can use a lot more of that capacity, and we recommend setting this to about 10%. Using the capacity within these limitations prolongs the lifespan of your battery.
• Change the ‘Discharge Floor’ to the correct percentage and click OK.

7. Click on ‘Tail Current’ to open this setting

• The tail current is another parameter that the shunt uses to determine if the battery is fully charged. So the battery voltage has to reach the Charged Voltage, AND the current has to drop below a certain percentage for the shunt to declare the battery fully charged. That current percentage is the Tail Current parameter. What you should program your tail current to is dependent on the battery type you have in your system. For AGM or lead-acid batteries, we recommend between 1-3%. For lithium batteries, we recommend setting this to 1%.
• Change the ‘Tail Current’ to the correct percentage and click OK.

8. Click on ‘Charge Detection Time’ to open this setting

• In addition to the Charged Voltage and the Tail Current, the shunt uses the Charged Detection Time to determine when the battery is fully charged. So, when working together, the voltage has to reach the Charged Voltage you set, the current has to drop below the Tail Current percentage you set, and it has to do this for a certain amount of time for the battery to be declared fully charged. The time it has to hit these parameters for is set in the Charged Detection Time. The default is 3 minutes, and this is also what we recommend.
• If the ‘Charge Detection Time’ is not 3m, change it to 3m and click OK.

9. Click on ‘Peukert Exponent’ to open this setting

• The Peukert Exponent is a parameter that refers to the way that the battery deteriorates over time. This needs to be programmed according to the type of battery you have. For AGM batteries, it can be set to 1.25%, and for lithium batteries, we recommend setting it to 1.1%.
• Change the ‘Peukert Exponent’ to the correct percentage and click OK.

10. Click on ‘Charge Efficiency Factor’ to open this setting

• The charge efficiency factor refers to how efficiently the battery will charge and discharge. This parameter is directly linked to the type of battery in your system. AGM/Lead Acid batteries and Lithium batteries have different efficiencies when it comes to charging and discharging. Although minimal, the shunt needs to be programmed to read these efficiencies to monitor the system accurately. So, for AGM batteries, we recommend setting the charge efficiency factor to 90%. For lithium batteries, we recommend setting it to 95%. Victron recommends setting this to 99%, so anywhere between 95-99% is okay for the charge efficiency factor.
• Change the ‘Charge Efficiency Factor’ to the correct percentage and click OK.

11. The shunt is now connected and ready to begin monitoring

Once the shunt is connected, you will need to charge your battery to 100% for the shunt to calibrate and finalise the programming. The shunt will recalibrate itself each time the battery reaches 100% charge to ensure that the programming is still running as it should and that it is giving accurate readings.

These are the basic settings that you will need to program to get your shunt set up and effectively monitoring your battery system. While there are plenty more settings that can be programmed within the VictronConnect app (see the VictonConnect Manual for more), however, these additional settings are not necessary for the shunt’s basic functionality.

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