The Complete Buyers Guide To Caravan & Camping Power System Monitoring

You can’t manage what you can’t measure. That applies to budgets, waistlines, and most definitely caravan batteries. Without a monitoring system, you’re guessing how much power you have left, and the consequences of guessing wrong range from a dead fridge overnight to flat batteries that can’t start your water pump in the morning.

A power monitoring system shows you exactly what’s happening in your electrical system: how much energy is stored in your batteries, how much is coming in from solar and charging, how much is going out to your appliances, and critically, how long your power will last at the current rate of use. It’s one of the most useful upgrades you can make, and for the price ($100 to $400) it pays for itself in avoided flat batteries and smarter power management.

What Power Monitoring Tells You

State of charge (SOC): The percentage of energy remaining in your battery. This is the single most important number. A basic voltmeter gives you a rough idea (12.6V is full for AGM, 12.0V is flat), but voltage alone is unreliable because it fluctuates under load. A proper monitor calculates SOC by tracking energy in and out (coulomb counting), which is far more accurate.

Current draw (amps): How much power your appliances are pulling right now. This tells you which devices are the big consumers and helps you identify unexpected drains.

Charging current (amps in): How much power is flowing into your batteries from solar, the DC-DC charger, or the 240V charger. This tells you whether your charging is keeping up with your usage.

Time remaining: Based on current draw and battery state, how many hours until your batteries are empty. This is the number that actually drives decisions: “We’ve got 14 hours of power left” is a lot more useful than “the battery is at 63%.”

Historical data: Some monitors track power in and out over days and weeks, letting you identify patterns. You might discover your fridge draws 30% more overnight than during the day (hint: it’s working harder because the sun’s not on the van), or that your inverter has a small standby draw you hadn’t accounted for.

Types of Monitoring Systems

Battery Shunts (Standalone)

A shunt is a precision resistor installed on the battery’s negative terminal that measures all current flowing in and out. It connects to a display panel or, increasingly, a Bluetooth module that sends data to your phone. Shunts are the most accurate way to monitor battery state of charge because they track cumulative energy flow rather than relying on voltage alone.

Installation requires connecting the shunt to the battery negative terminal so that all loads and charging sources pass through it. It’s a straightforward job for anyone comfortable with 12V wiring.

Integrated System Monitors

Brands like Redarc, Enerdrive, and BMPRO offer integrated monitoring systems that display battery status alongside solar input, DC-DC charging, water levels, and sometimes tank temperatures on a single screen or app. These are typically installed as part of a complete power system and work best when paired with the same brand’s chargers and controllers.

The advantage is a single interface for everything. The downside is cost and brand lock-in: a Redarc RedVision system works best with Redarc chargers and controllers.

Basic Voltmeters

A simple 12V voltmeter panel gives you a rough indication of battery state but is the least accurate option. Voltage readings fluctuate under load (the battery reads lower when the fridge kicks in) and during charging (reads higher than actual SOC). A voltmeter is better than nothing but significantly worse than a proper shunt-based monitor. If your van came with a basic voltmeter, consider it a starting point, not a solution.

Product Recommendations

Victron SmartShunt

The Victron SmartShunt is the go-to battery monitor for caravanners, and for good reason. It’s a shunt-based monitor with Bluetooth connectivity that sends all data to the free Victron Connect app on your phone. SOC, voltage, current, power, time remaining, and historical data are all displayed clearly. It works with any battery type (AGM, lithium, gel) and integrates with other Victron products if you have them, but works perfectly standalone too.

Installation is clean: the shunt connects to the battery negative terminal, and the Bluetooth module attaches to the shunt. No display panel needed (though Victron makes optional ones). Around $100 to $150. This is the best value battery monitor on the market.

Redarc RedVision System

Redarc’s integrated monitoring system displays battery, solar, DC-DC charger, and water tank data on a touchscreen display and the RedVision app. It’s designed to work with Redarc’s Manager30 charger and MPPT solar controller, providing a unified view of your entire power system. The interface is polished and easy to understand.

The RedVision system is more expensive than a standalone shunt ($300 to $500 for the display and wiring harness), but if you’re running Redarc components it’s the obvious choice. For those with mixed-brand components, the Victron SmartShunt is usually a better fit.

Enerdrive ePRO Plus

Enerdrive’s battery monitor offers a physical display panel (mounted inside the van) showing SOC, voltage, current, and time remaining. It’s a shunt-based system with good accuracy and a clear, easy-to-read display. Works well paired with Enerdrive batteries and chargers but is compatible with any system. Around $200 to $280.

BMPRO BatteryPlus35

An Australian-made battery management system that combines charging, monitoring, and protection in one unit. It monitors battery state, manages charging from solar and 240V, and provides load disconnect protection to prevent over-discharge. More of a complete management system than a standalone monitor. Around $350 to $450. Best suited for new builds where you’re installing a complete power system from scratch.

Which Monitor Should You Buy?

For most Big Lappers: The Victron SmartShunt at $100 to $150 is the clear recommendation. It’s accurate, affordable, phone-based (no extra display panel to install), and works with every battery type and brand. If you already have Victron solar controllers or inverters, it integrates into the VRM ecosystem for comprehensive monitoring. If you don’t, it works just as well standalone.

If you want a physical display: The Enerdrive ePRO Plus puts all the key numbers on a permanently mounted panel inside the van, which some travellers prefer over checking a phone app. It costs more but eliminates the need to pick up your phone every time you want to check battery state.

If you’re building a complete Redarc system: The RedVision makes sense as an integrated solution. It’s more expensive but provides a unified view of your entire Redarc-based power system.