Sproat Lake, Vancouver Island, BC

What is an Electrical Shunt?

What is an Electrical Shunt?

What is a shunt and why do you need one in your battery based system?

Imagine if your phone only showed its battery voltage, like 3.7 volts or 4.2 volts. You’d have no idea how much power is left and when it might die. That’s where a shunt battery monitor comes in!

Instead of puzzling over voltage readings like 12.5 volts or 24.2 in a 24 volt, or 49.5 in 48 volt systems, a shunt tells you the state of charge. Just like your phone’s battery indicator shows 80% or 60% full, a battery monitor shunt gives you a clear picture of your battery’s actual status.

With a shunt, you’ll always know how much juice you have left, making it easier to plan and manage your energy usage efficiently. It’s like having a fuel gauge for your batteries, ensuring you’re never caught off guard by unexpected power loss. Stay informed and stay powered up with a shunt!

How does this all work?


Imagine you have a water hose, and you want to measure how much water is flowing through it. But the water is too fast and strong to measure directly. So, you decide to create a small side path for some of the water to flow through.

How can we measure the amount of water flowing through a hose?

The side path is like a little stream that connects to the main hose. By having some water flow through this smaller stream, it becomes easier to measure how much water is going through the main hose.

In electricity, we sometimes want to measure how much electric current is flowing through a wire, just like measuring water in the hose. But electricity is invisible and hard to measure directly. That’s where an electrical shunt comes in!

man in brown and white plaid dress shirt and yellow hard hat holding black and orange

An electrical shunt is like that small side stream for electricity. It’s like a special device, like a tiny bridge, that connects to the main wire. When electricity flows through the main wire, a little bit of it takes the side path through the shunt. This makes it much easier to measure the total amount of electricity flowing because we can measure the current in the shunt, which is easier to handle and understand.

So, the electrical shunt helps us know how much electricity is passing through the main wire by diverting some of it through a smaller, more manageable path. Just like the little stream helps us measure the water flowing in the hose!

Below is a Magnum Energy Battery Monitor Kit or BMK which provides detailed information on the status of the system’s battery state of charge or SOC, the amount of amps going in and going out of the system and other such important information.

Want a Magnum BMK? You can get one in our Amazon Associates products page or simply if your local to order for pick up.

Magnum Energy BMK

The shunt is designed to divert only a small portion of the total current in the circuit while accurately measuring that diverted current. Shunts are commonly used in various applications, including electrical power systems, electronic devices, and industrial processes.


Ohm’s Law

The basic principle behind the operation of a shunt is Ohm’s law, which states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance:

I = V / R

where: I = Current (in amperes) V = Voltage across the shunt (in volts) R = Resistance of the shunt (in ohms)

Shunts are often constructed with a low resistance value, typically in the milliohm range, to ensure that they have minimal impact on the overall circuit’s behavior. When current flows through the main circuit, a small portion of it diverts through the shunt resistor due to its low resistance. This diverted current can then be measured and used to calculate the total current in the circuit using Ohm’s law.

Shunts are widely used in ammeters and digital multimeters to measure electrical current accurately. They play a critical role in various electrical systems, helping engineers and technicians monitor and control current levels in different applications, ranging from small electronic circuits to high-power electrical distribution networks.

Below is a Victron Energy Smart Shunt set up in a simple circuit diagram taking from the Victron Energy web page. Every device load connected after the shunt will be measured.


Experience the Power of ! With a simple Bluetooth connection, you gain instant access to comprehensive insights about your system’s production, consumption, and state of charge. Keep track of your solar system’s performance and have descriptive records at your fingertips. Plus, if you leave it continuously powered on, it will maintain these valuable records for a lifetime.


Want a for yourself? Get one instantly form our Amazon Associates products page or simply if your local to order for pick-up.

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