All guides · Batteries and charging
A battery monitor can make it easier to plan a night at anchor. I primarily want to use it to see the net current to and from the battery and monitor consumption over time.
Three numbers that tell you different things
| Reading on the screen | What it tells you |
|---|---|
| Voltage in V | The battery's current voltage. This is affected by factors such as charging and load. |
| Current in A | How fast current is flowing in or out right now. |
| State of Charge in % | The monitor's calculated remaining capacity based on measurements and settings. |
The percentage is therefore a calculated figure that requires a correct starting point. Furthermore, a shunt is not a BMS, and it does not replace the battery's protection or the system's fuses.
The current must pass through the right place
A SmartShunt measures via a shunt in the battery's negative connection. In a standard battery monitor installation, consumers and chargers must be connected on the system side so their current is registered. A connection directly to the battery's negative terminal that bypasses the shunt can result in misleading readings.
It is especially worth checking this when adding solar panels, an inverter, or a new charger later on. Installation must follow the diagram specific to your battery bank.
Calculation example: solar panels and refrigerator simultaneously
If the solar panels provide 12 A and the boat's total consumption is 7 A, the net current into the battery is approximately 5 A. A battery monitor can show the net supply; it does not necessarily show the two currents separately.
This explains why the charger's display and the battery monitor's display may show different numbers without anything being wrong.
The setup determines whether the percentage is useful
Set the actual battery capacity and the relevant values for the battery type. Follow the manual for detecting a full battery and synchronization. Randomly pressing “100%” does not make the battery full and can give a false sense of range.
Afterwards, I will check if the display reacts sensibly when a known consumer is turned on and when charging starts. If the numbers deviate, investigate connections and settings before judging the battery as defective.
Do you need a phone or a fixed screen?
The SmartShunt is read locally with VictronConnect via Bluetooth. It can also be part of a system with a compatible GX device. Remote access from home requires more than just Bluetooth. If you always want a visible battery percentage at the dashboard, a screen and other equipment should be included in the budget.
Send an overview of your battery bank, largest consumers, and existing Victron equipment. Then I will help you find a suitable monitor and the necessary connections.
Sources and manufacturer documentation
This guide is written by SejlStrøm. Technical information was verified on September 22, 2026. Always use the documentation for the specific model and version.