If you rely on batteries to power your RV while boondocking or dry-camping, a battery monitoring system is an essential piece of equipment. Most RVs don’t come with one. Here are my top picks for RV battery monitoring systems in 2021.
With many battery monitoring systems (BMS) out there to choose from, which one should you buy?
Battery monitoring systems have evolved quite a bit over the last few years. The most popular BMS units have very modern displays, Bluetooth and WiFi capabilities. Their firmware is even updated regularly via a mobile app.
Are older units still worth buying? Sure they are if integration and modern asthetics aren’t important to you. Despite their solid battery monitoring features, older battery monitors without these modern features are not the first choice of today’s DIY RVer.
Why Have a Battery Monitoring System?
Without a battery monitoring system there’s no way for you to know the status of your batteries.
A battery monitoring system measures the amount of energy flowing in and out of your batteries at all times. These measurements are used to calculate your battery’s state-of-charge or state-of-discharge. The BMS works like a fuel gauge for your batteries.
A battery monitor is also very useful to measure the exact amount of current (in Amps) each piece of equipment uses. Simply power up the piece of equipment and watch the current value change.
A BMS can also tell you:
- How much energy is going in or out of your batteries at any give point
- What percentage of your total battery capacity is available
- How much time is left before your battery is fully charged or drained
Some systems allow you to set alarms to switch equipment on or off when a certain condition is met. For example, you may want to automatically start a generator when your batteries get below 50 percent.
What Comes With A Battery Monitoring System?
Battery monitoring systems first need a way to measure energy flowing in and out of your battery. They also need a way to display that information to you in a meaningful way.
This is the remote monitor that you’ll mount in your RV. Most have buttons to switch modes and program the monitor. Most manufacturers offer your choice of flush mount or surface mount models.
For years, monitor displays were simple numeric displays. Newer systems like the new SIMARINE PICO system now have larger graphical displays.
Most monitors also provide some way to program the system from the display. At a minimum, you’ll need to set the maximum battery capacity (in Amp Hours) and system voltage (12, 24 or 48 volts).
A shunt is a device that measures energy flowing in and out of your battery. It reports those measurements in real-time back to the display unit. The battery voltage is also sent to the display unit.
The monitor base unit then calculates the current (in amps) flowing in and out over time, adding or subtracting from the remaining battery capacity to determine the percentage available.
The shunt is installed next to the battery and connected directly to the negative battery terminal.
Note: It is very important that all energy flowing in or out of the battery goes through the shunt. Equipment connected directly to the battery, bypassing the shunt, will cause inaccurate battery status readings.
Cables, Voltage and Temperature Sensors
Some packages include the cables and fuses needed to connect the shunt and battery voltage inputs to the display monitor.
Some display units can also take a temperature sensor input.
Remote access via a mobile application is a popular feature in the newer BMS models like the Victron and SIMARINE systems. They provide remote monitoring and setup via Bluetooth or WiFi.
Mobile apps also provide a means to keep the BMS automatically updated with the latest software and firmware. This is a key feature in my opinion that can help future-proof your BMS investment.
Some systems provide additional features for monitoring extra batteries and even storage and waste tank levels. Expect to pay a little more for these additional features.
TOP RATED Battery Monitoring Systems
Here are my top picks for RV battery monitoring systems available on the market. All systems include shunts.
SIMARINE PICO Battery Monitor – Standard Package
The SIMARINE PICO Smart Monitor includes battery monitoring. It also has the capability of monitoring storage tank levels and other voltage sources.
The SIMARINE PICOone package is my top pick for a BMS primarily because of the well designed user interface, ease of use, and modular design. It includes a combo shunt module which has inputs for a couple tank sensors. The free mobile app can be used for remote monitoring and keeping the unit updated with the latest firmware.
The PICO STANDARD package includes more sensor inputs and can be expanded with additional SIMARINE modules.
See the PICO system in action in this video.
Victron BMV-700 and BMV-712 Battery Monitors
The Victron BMV 700 series battery monitors are a very popular battery monitors. They can be integrated with other Victron equipment or as standalone battery monitors. A shunt is also included.
The main difference between the Victron BMV-700 and BMV-712 is Bluetooth. The BMV-712 has built-in Bluetooth capability. The BMV-700 requires the Victron Bluetooth dongle if you want to connect to the Victron mobile app or other Victron equipment.
See the Victron BMV-712 Monitor in action.
Bogart Engineering TriMetric (TM-2030 RV)
The TriMetric battery monitors have been a popular choice for many years. My first BMS was a TriMetric. It comes with a shunt and optional installation kit with cables.
The basic numeric display on the TriMetric shows the essential battery state-of-charge data. Unfortunately, Bogart Engineering hasn’t updated the TriMetric in many years to keep up with the competition.
The latest TriMetric TM-2030 RV model is a stable option. There is no mobile app to go with this unit and it does not support wireless capability.
See the TriMetric TM-2025 RV battery monitor in action.
Blue Sea System M2 SoC Meter
The M2 SoC Monitor has a compact easy to read OLED display for monitoring the state-of-charge for one battery bank. You can also program it to trigger a remote generator start.
The Blue Sea M2 SoC Monitor can also monitor up to three voltage inputs. The shunt is also included. There is no wireless connectivity or mobile app option for this unit.
See the Blue Sea M2 in action.