Review of Victron BMV-712 Battery Monitor and MPPT 100 Controller

I recently installed a battery monitor and a solar power system in my 25C9.4SB Bigfoot truck camper. There are many reviews of battery monitors and solar charge controllers on the Internet. What makes this particular review a bit different is that it features a smart phone interface and display that provides an amazing amount of functionality and information. Called the VictronConnect, this smart phone app provides readouts, settings, and historical information—via Victron Bluetooth Smart Dongles—for the Victron BMV-712 battery monitor and the Victron BlueSolar MPPT 100/30 charge controller.

Victron Energy is based in The Netherlands. They design and manufacture small to very large-scale solar systems and components of all types including battery chargers, inverters, batteries, monitors, solar charge controllers, solar panels, etc. Their products are used worldwide in residential, industrial, marine and automotive (RV) applications.

After reading about the benefits of having a battery monitor on many websites, including here on Truck Camper Adventure, I wanted to install a battery monitor in my camper so that I could know the state of my batteries while boondocking. At first I did not know what kind of battery monitor I wanted to get much less what kind of solar power system and charge controller I needed to install. I was starting at “square one” with no prior experience in solar power.

After looking at several battery monitors online, I learned that the displays were not entirely straightforward and simple. The size of the displays were invariably small resulting in button pushes, scrolling, abbreviations, etc. to see the various readings and to change settings. In this day and age, it seemed there should be something better.

Then I read an online article that in the opinion of the author, the Victron BMV-712 battery monitor was the best. I had never heard of a Victron battery monitor before, but kept it in mind, Googled it one day and hit on a website that had it on sale for a very reasonable price compared to other websites and other monitors. I had found the Victron BMV-700 on on the Peter Kennedy Yacht Services (PKYS) website. I noticed PKYS is located in Annapolis, Maryland and is a business that specializes in marine electrical systems. Normally a yacht supply house in a place as upscale as Annapolis would make me think twice about the price, but the sale price was actually quite good. I also noticed on the website that Peter Kennedy is an ABYC certified marine electrician. If you think that an RV electrical system is important, it pales in comparison to the critical nature of a marine electrical system. I had a few questions I asked via email and Peter Kennedy answered each one personally, so I was happy to put my trust in him.

What had caught my eye on the bottom of the webpage was a picture of a smart phone display of the battery monitor made possible by using a Bluetooth device called the Victron VE.Direct Bluetooth Smart Dongle. The display was outstanding—no abbreviations, everything clearly labeled, no scrolling, proper units of measure, great graphics. That is exactly what I wanted. I did some more checking and read the BMV-700 data sheet and manual on-line, all of which convinced me I had found the battery monitor I was looking for. I ordered it and the Bluetooth Smart Dongle from PKYS. The BMV-712 sale price ($144) plus the dongle sale price ($50) together were less expensive than other monitors I had looked at on other websites. The BMV-712 includes a 500 amp/50 millivolt shunt, data cable, and fused positive wire.

The BMV-712 webpage on PKYS includes a lot of links and an installation suggestion that if the shunt has to be located in an exposed place, they recommend mounting it in a Blue Sea 2719 Maxibus Cover for protection. My battery box did not have room for the shunt, so I simply installed it on an inside wall of a cabinet next to the battery box that I reinforced with 3/4-inch plywood. The shunt fit perfectly in the 2719 Maxibus cover. The cover has end knock outs for the negative cable to and from the shunt and I used a side knock out on the base for the data cable. Not only does the Maxibus cover protect the shunt terminals from accidental shorting, but it also protects the circuit board where the data cable and the positive wire connect. I suggest installing the shunt in the Maxibus cover regardless of its location.

The Victron BMV-712 battery monitor is about 2.5 inches in diameter and is only 1.25 inches deep. You need about 1 inch of extra space to have room for the VE.Direct cable plug on the back of the monitor. The Bluetooth dongle is only about 2.5 inches wide and is a surface mount. The data wire from it can’t be disconnected from the dongle (I opened it up and checked) so when you want that cable to penetrate something, you have to make a 1/2-inch by 1/4-inch opening to get the VE.Direct plug through, even though the cable itself is only about 3/16 inch in diameter.

One of the many well-engineered features of the BMV-712 is that the wiring from the shunt to the monitor uses a ready-made six-conductor data cable with network type plugs. It is plenty long (10 meters). I stowed the extra length underneath my counter top. There are no terminations to make—just plug it into data ports on the shunt circuit board and the back of the battery monitor. Easy. It’s the gray cable in the shunt pictures above. The connection from the monitor to the Bluetooth dongle is simple as well. A four-conductor data cable is hardwired to the dongle and it plugs into the VE.Direct port, also on the back of the battery monitor. The positive connection from the battery to the shunt was very well designed. The small red wire came ready-made with a 3/8-inch ring terminal with an in-line fuse for the battery end. On the shunt end it has a small single prong, round plug that fits into a corresponding receptacle on the circuit board—you actually depress the orange tab that you can see in the picture of the shunt, and when released, it locks the plug into the receptacle. There is no need for a positive wire from the battery to the monitor as it is carried from the shunt circuit board in one of the data cable conductors. Clever. All of the connections took literally less than a minute. After everything was installed and the batteries were connected (negative last), I turned on the app on my iPhone and Victron initiated a quick, automatic firmware upgrade to the monitor. After the firmware update was completed, everything came up immediately with a perfect display on my iPhone.

The VictronConnect app iPhone display shows the battery voltage, how many amps are being used (-4.8 amps in this screen shot), state of charge percent, consumed amp hours since last full charge, time remaining at the current discharge rate before the battery needs recharging, relay status, and a link to the history. The wrench/gear icon in the upper right is the link to settings. The time remaining display is the time to reach the discharge floor, which is set at a default level of 50 percent of the capacity of the battery. The discharge floor setting can be changed, but 50 percent is recommended by Lifeline. The relay can be used for more complex systems—as an example, it could be used to signal a generator to start-up if the battery reached a specified state of discharge.

When you tap the settings icon it gives you a menu to change the settings of the battery, the relay, alarms, the display, and the shunt. When you tap the battery settings choice, this is a screen shot of what you can change. Here I’m setting the battery capacity of my two Lifeline 12 volt batteries in parallel to 200 amp hours. I’ve already set the fully charged voltage to 13.2 volts. (I put my batteries on an AGM BatteryMinder for a month, then installed them in the camper and after allowing them to “settle” overnight, the battery monitor showed them at 13.18 volts, so I set the fully charged voltage at 13.2 volts). On this screen shot, I have yet to change the Peukert exponent from the default 1.25 down to 1.12 which is the value specified by Lifeline. In any case, you can see how easy it is to change battery settings. When you tap on a setting, it is highlighted in orange, the number keypad pops up, you just enter the new number and tap “Done”. Very intuitive and simple.

There are many other settings available. The settings screen for the display allows you to select what data is displayed on the monitor itself, adjust scrolling speeds, turn the monitor back light on or off, and adjust its brightness. The settings screen for alarms allows you to set an alarm for low voltage, low state of charge (SOC), and other parameters. The relay settings screen allows you to control how the relay is utilized. If you use a different shunt than what is provided, the shunt current and voltage can be changed on yet another settings screen.

When you tap “History” on the battery monitor display this is what is shown. I won’t repeat all the information shown in the screen shot above. Suffice to say, information such as the deepest ever discharge and average discharge will help tell you if your battery utilization is detrimental to your battery life or not. This screen shot was taken soon after installation so there wasn’t enough data to calculate everything yet.

What impresses me is how easy it is to read and use the Victron smart phone displays. I’m very glad I did my research and found what I wanted. With the detailed displays on a smart phone there is never a need to decipher button pushes, cryptic symbols, abbreviations, scrolling, or blinking LEDs on tiny readouts. On the small display on the battery monitor itself, I just leave it showing the battery voltage and never touch it even though it has many other outputs. I find that I only use my iPhone to check my batteries. Victron updates your free VictronConnect app software as needed. And through the app and the Bluetooth connection, Victron also updates the firmware on the Victron equipment – but that does not happen often. A firmware update, if there is one, takes place when you have a cellular or Wi-Fi connection to the Internet. The Bluetooth connection from the dongle to your smart phone does not need cellular or Wi-Fi access – just enable Bluetooth on your smart phone settings.

My next hurdle was to figure out what size and type of solar charge controller I wanted. I’d read several articles online that AM Solar, a company that deals exclusively with RV solar components and installations, was good to work with. I checked out their website and I emailed Roger Carroll who does their sales and tech support a lot of questions. I wanted to make sure my charge controller would be compatible with whatever I chose for my roof solar panels and my portable panel. He was very helpful.

Although most controllers have settings for each type of battery (wet cell, AGM, gel, etc.), they usually do not allow specific adjustments for the absorption, float or equalization voltages. My Lifeline AGM GPL-27T batteries at 70 degrees F require 14.4 volts for absorption, 13.4 volts for float, and 15.6 volts for equalize (conditioning). Many controllers had charging voltages for AGM batteries that were other than what’s required by Lifeline. I wanted a controller with output that matched my battery’s requirements.

I preferred to stick with Victron. I found that the Victron BlueSolar MPPT 100/30 controller had VE.Direct capability and could be connected to another Bluetooth dongle and controlled on my smart phone just like their battery monitor. With two 100-watt roof panels and a portable (with no controller), the next size smaller Victron MPPT is rated for 15 amps which is not high enough for all three solar panels. So I got the 30 amp model (the 100/30 in the model number stands for the 100 volt / 30 amp capacity of the unit). A few questions to Roger and checking the MPPT 100/30 data sheet, manual, and videos online confirmed that the MPPT 100/30 with Bluetooth connectivity would give me perfect control.  The MPPT 100/30 has eight different charging settings (controlled by a little rotary switch on the bottom of the unit) for different types of batteries including lithium. But through your smart phone, you can change the specific voltages and other factors within those settings to match exactly what your battery requires. One other feature of the MPPT 100/30 I liked was the terminals for the PV panels and battery connections accepted heavier 6 AWG cable to reduce voltage drop.

The voltages of my two roof panels and my portable are compatible for parallel connection. All three panels are controlled by the Victron BlueSolar MPPT 100/30 controller and Bluetooth Smart Dongle I bought from AM Solar.

I mounted both Bluetooth dongles and the battery monitor in a trim space below my kitchen countertop in front of the sink. The Bluetooth transmission is strong enough where I can receive either the battery monitor or the MPPT controller signals outside of my fiberglass camper or even in the cab of my pickup. It does not have to be line of sight (though to receive the signal in the cab of the pickup, I believe it is helpful that the dongles face the dinette/kitchen passageway and do not face away from the rear pickup window).

Because the MPPT 100/30 has no display, I mounted it inside a cabinet on ¾-inch plywood. That made the installation super easy because I could put the controller close to the batteries as it should be without having to worry about putting it some place where I could see it. The MPPT 100/30 is a bit heavy so you do not want to mount it on what is often thin paneling material anyway. You can see the VE.Direct cable to the dongle plugged in at the bottom right of the controller. The 40 amp circuit breaker was a recommendation by AM Solar that I sourced elsewhere to get a panel mount.

I also added Blue Sea “Mini” battery switches so I could isolate my controller from the battery. The self consumption of the MPPT 100/30 is 10 milliamps so if I store my truck camper in my barn for a few months over the winter or in between trips with no sunshine on the panels, the controller will draw 7.2 amp hours per month and be a potential drain on the batteries. I could certainly disconnect cables at some point to isolate the controller, but a switch is so much easier considering how many times I might park inside over the lifetime of the camper. If you store your rig outside in the sun all the time, no need for switches. The BMV-700 battery monitor only draws less than 4 milliamps; since that would only be 2.8 amp hours per month, there is no real need to isolate the battery monitor.

This is a screen shot of the MPPT 100/30 display. It tells me how many watts my panels are producing, the voltage they are producing, the voltage and amps the MPPT controller is putting into the batteries, the charger state (“Bulk” in this instance), and the history link. The same settings icon is in the upper right.

Move through two settings screens and above is a screen shot for the default battery settings for the MPPT 100/30 when it is set at “2” battery type (AGM) on the rotary switch on the bottom of the 100/30 unit. Note that with the default charge settings “ON,” the values are predetermined and are shown in light font indicating they cannot be changed.

When you slide the “Use default charge settings” to “OFF”, the screen above shows what can be customized—the values are now in the normal, darker font indicating they can be changed.

In the screen shot above, I have turned on the equalization cycle and have selected to change the default float voltage of 13.80 volts and will enter the Lifeline specified float voltage of 13.40 volts. You can change the absorption, float and equalization voltages to match exactly what your battery manufacturer requires.

The MPPT history screen keeps the history for the past 30 days—all you have to do is keep scrolling down. For each day’s history, it is hard to tell in a picture, but the lower information bar for each day can be swiped left to fully show the charge time in each mode. In the day marked “0” or “Today” that information bar is as it normally displays with the battery voltage shown. In the day marked “1” day ago or “Yesterday” I have swiped left to hide the battery voltage and expose the entire charge time display for that day.

The only minor downside for my particular system is that battery temperature control is based on the controller temperature. The MPPT 100/30 does not have an input connection for a separate temperature sensor from the battery. If your AGM batteries are in your cabin somewhere along with the controller, this is really not an issue as they will be close to the same temperature. This is another reason to mount the controller as close to the batteries as possible, in addition to reducing voltage drop. The default temperature compensation of -16.2 millivolts per degree Celsius can be adjusted. Keep in mind that the temperature compensation factor is not linear (according to the Lifeline manual for their AGM batteries), so selecting a value that is closest to the middle of the temperature range at which your batteries will operate is probably best.

Installation of the Victron components was very easy and everything worked perfectly and seamlessly together the instant it was powered up. The design and engineering of the components, software and displays are extremely well thought out. My Victron system (the BMV-700 battery monitor, the BlueSolar MPPT 100/30 solar controller, the VE.Direct connectivity, the Bluetooth Smart Dongles, the VictronConnect App, and my smart phone) makes it extremely simple to see, use and control my batteries and solar system.