Monitor Systems

How much energy is left in your battery, and will your fresh water last until the next stop? The right monitoring setup helps you keep track of your reserves in your camper van or motorhome. Choose a dedicated battery or tank monitor, or bring several readings together on one central display.

Which monitoring setup do you need in your camper van?

What matters is which information helps you on your travels: do you want to know your leisure battery’s state of charge, check your water levels or see how your battery, chargers and appliances work together? You do not automatically need a comprehensive monitoring system for every task.

Under “Battery monitoring”, you will find solutions for keeping track of your energy reserves, while “Tank monitoring” covers fluid level monitoring. Combined control panels bring several readings together and, depending on the model, also provide controls. Communication hubs and system displays offer further options for connecting compatible devices.

Battery monitoring: checking voltage or assessing remaining energy?

A voltmeter shows your current battery voltage. This is useful for checking your electrical system, but it does not replace a reliable state-of-charge display. With LiFePO4 batteries in particular, the voltage changes very little through much of the discharge cycle. Voltage alone therefore provides only a limited indication of the energy remaining.

If you want a better understanding of your energy reserves, consider a battery monitor with a shunt. A shunt is a measuring resistor used to measure charging and discharging currents. Together with the configured battery settings, the monitor uses these measurements to calculate the state of charge. Depending on the model, it may also display current, voltage, amp-hours consumed or an estimated time remaining.

The estimated time remaining is not a guarantee: switching on a powerful appliance or changing the charging input will also change the calculation.

Choosing the right battery monitor and shunt

First, check that the battery monitor supports your system voltage and battery type. The shunt must be rated for the currents that can actually occur in your system. Powerful inverters in particular can draw considerably more current than lighting, a fridge or USB chargers.

A shunt’s amp rating describes its current capacity, not the battery capacity it is suitable for in amp-hours. A 500 A shunt is therefore not intended exclusively for a 500 Ah battery. Alongside the measuring range, check the model’s permitted continuous and short-term current ratings.

For a useful state-of-charge calculation, all relevant charging and discharging currents must be measured. In typical installations with a shunt in the negative cable, appliances and chargers must not bypass the shunt through a direct connection to the battery’s negative terminal. Correct battery settings and synchronisation when the battery is fully charged are equally important.

Display or Bluetooth: how would you like to check your readings?

A fixed display is practical if you want to check your battery status at any time without using a smartphone. Look for good readability, a suitable mounting location and sufficient installation depth. Depending on their design, compact displays may also integrate into your chosen switch range.

A Bluetooth-enabled battery monitor can be a good choice if you prefer to view your readings in an app and do not need a separate display. Check which data the app provides and whether the connection works reliably at the planned installation location.

If your battery already has built-in Bluetooth monitoring, first consider which additional information you need. A separate battery monitor can be useful for monitoring an entire battery bank or feeding data into a central display, for example. For occasional checks on a single battery, the existing app may already be sufficient.

Tank monitoring: the display and sensor must be compatible

A tank monitor helps you judge when to refill your fresh water or empty your waste water tank. Alongside the display, you need a suitable tank sensor to measure the level. Before buying, check which components are included and which you need separately.

The sensor must be suitable for the tank contents, tank height and intended installation. Tank material, the mounting opening and available installation space can also affect your choice. Not every sensor works with every display: the measuring method and electrical signal must be compatible.

If you want to reuse an existing sensor, check its exact specification. A similar shape or the same number of connecting wires is not enough to establish compatibility. Also check how the system needs to be configured for your tank; with irregularly shaped tanks, half the fill height does not automatically mean half the water capacity.

Combined control panels: several readings in one place

A combined control panel brings several displays together in one unit. Depending on the model, it may show battery information, tank levels and other readings, or let you switch certain vehicle functions.

This is useful if you want a quick overview when you enter the vehicle or before setting off. However, compare the actual features carefully: a battery voltage display is not a full battery monitor, and a connection for a tank sensor does not mean that the sensor is included.

Check which monitoring functions are built in, which sensors and shunts are required, and what can be added later. This helps you avoid choosing a panel that fits neatly into your conversion but cannot provide the readings you need.

Central system monitoring: connecting your devices

If you want to monitor several compatible components together, a communication hub such as the Victron Cerbo GX can be useful. It brings together data from connected devices and makes it accessible through suitable interfaces. A system display shows the information; the measurements come from connected devices, shunts or sensors.

This type of setup can help you view battery status, solar output and inverter/charger operation together, for example. Which readings are available and which settings you can change depends on the connected components and how they are integrated.

Choose your monitoring setup to suit your existing or planned system. Check the specific device models, interfaces and connecting cables supported. An identical plug or a general reference to “CAN bus” does not guarantee compatibility.

Remote monitoring: access beyond your vehicle

Bluetooth generally provides access when you are close to the vehicle. If you want to check your system remotely from home or while you are out, you need a system that supports remote access and an internet connection in the vehicle.

Depending on the setup, supported online portals let you view current readings, historical data or notifications. Check which functions are available and whether you also need a gateway, router or other accessories. Consider the ongoing power consumption of these components too, especially if your vehicle will be parked for extended periods.

Monitoring, alerts and protection serve different purposes

A display makes a low state of charge visible, but it does not automatically disconnect appliances. An alarm function does not necessarily mean that a suitable switching output is available either. If you need automatic disconnection, the monitoring equipment and suitable switching or protection devices must be designed to work together.

A low-voltage disconnect therefore serves a different purpose from a battery monitor. Likewise, system monitoring does not replace your lithium battery’s battery management system or the required fuses.

Use these points to narrow down your choice

• Information: Do you want to see battery voltage, state of charge, tank levels or several system readings together?
• Measurement: Which shunts, tank sensors or other sensors are required, and are they included?
• Compatibility: Do the system voltage, current ratings, interfaces and existing devices match?
• Access: Would you prefer a fixed display, a smartphone app or remote access as well?
• Installation and expansion: Are the mounting space, cable routes and connections suitable, and can you add the functions you may want later?