Hey friends, welcome back to Grand Adventure! I'm your host Marc Guido,
and in this week's episode we are going to install in our RV
a wireless Bluetooth battery monitor. We're going to explain to you what this is, how it works,
why you want one, and we're going to show you how we install it in our RV, so stay tuned!
So just last week we finished installing our new solar upgrade on the roof of our new RV, and our
lithium battery bank to store all that solar energy. Now if you didn't yet see that episode
I'll put a link right here on the screen. That way you can go back and check it out for yourself,
but now we are installing this battery monitor so we can keep track of both the state of charge
in our batteries, and the rate at which we are charging and discharging current from
our batteries. Now a battery monitor is just like having a fuel gauge in a car. You don't actually
need it to drive the car, but it sure does provide some valuable information. The same holds true
for a battery monitor. Boondocking is all about resource management, and power is one of those
resources you have when you're boondocking. Power management requires power monitoring.
Now people often use a voltmeter to estimate the battery state of charge, but that's
really not accurate. You probably already have a voltmeter installed in your RV, even if it's
just one of those rows of LEDs at 25, 50, 75 and 100 percent, but that only measures the battery's
true state of charge if the battery is completely at rest -- and in an RV batteries are seldom at
rest. There's always either a charge coming in from shore power or from solar, or some other way
to charge your batteries, and there's always some sort of charge going out. There's always something
using the battery to power itself even if it's just a little parasitic drain on your battery.
As a result, voltmeters are a very inaccurate way of measuring the state of charge of your battery.
Now instead, a battery monitor keeps track of the amount of amp-hours removed from a battery
during discharge and the amount of amp hours returned to the battery during the charging cycle.
It then uses that information to calculate the true state of charge of the battery.
It also passes along information including amp-hours or watts used, amp-hours or watts
replenished to the battery, the rate of discharge, the rate of charge, and the voltage of your
battery. Most battery monitors connect to an external display to show their information,
but that necessitates running a cable to a display unit mounted somewhere in the RV living space.
Now that's where a Bluetooth battery monitor comes in. Now you may not realize it but you already own
a wireless display. Instead of a wired display it will send the information to your Android
or iOS mobile device via a free app available in the app store.
Now this PowerMon battery monitor from Thornwave Labs takes that even one step further. Now because
it will pair its Bluetooth signal with our RV Whisper system we'll be able to see its data on
our phone from anywhere in the world that we have an internet connection. Now all battery monitors
require a shunt, with all current going into or out of the battery passing through the shunt.
A shunt is basically just a precision resistor that measures the current passing through it.
The battery monitor then collects that information from the shunt
and provides it to you. Now the Thornwave PowerMon has its own internal 60-amp shunt
that you connect right with these two terminals right here, but we needed to be able to measure
more current and we wanted to install it on the negative side of the circuit, so we picked up this
inexpensive external shunt on Amazon to use in conjunction with the PowerMon. The external shunt
cost us about $30 and the PowerMon we bought directly from Thornwave Labs for $119. Now the way
that we're wiring the PowerMon we'll be able to monitor battery voltage, current passing into or
out of our batteries, and battery state of charge. You can use it on one or two battery banks.
Optionally you can also connect a relay to also implement a low voltage disconnect, an over
current disconnect, isolate a house battery from an engine battery, and remotely turn the relay
on and off. You can even use the PowerMon as a lithium iron phosphate battery charge manager.
Now you want to install the shunt as close as possible to the RV's battery bank. It's imperative
that you have all loads passing through the shunt. Now in our case we have one cable leading from the
battery to the common ground, and we have another negative cable connecting our battery directly to
our Xantrex power inverter. We're going to need to connect both of those cables to the load side
of our shunt to ensure that all loads are being accurately measured. So now our first step is
going to be to take those two negative cables that go to the loads and tie them off to the load side
of the shunt, and then take this little short 12-inch jumper that I bought and connect that to
the battery side of the shunt and to the battery terminal where the loads are presently connected.
Now one good thing, I'm not 100% sure if I've got the directions right between battery and load on
this shunt, but one good thing about the Thornwave is that I can actually reverse the direction
via the software in the app if I happen to get it wrong. And then we'll mount this on the wall right
here next to our battery disconnect and we will set about installing the battery monitor itself.
So there now we have the shunt installed with the loads on this side and the battery connected to
the left side. I should mention, you know, I mean there's nothing terribly dangerous about
working with 12-volt power. Still, I did turn the battery disconnect off while I was working and if
you don't feel qualified to do this yourself, hire a qualified electrician. But our next step
now is going to be preparing the wiring to connect our Bluetooth battery monitor from Thornwave Labs
to the new shunt. So now the way that we are going to wire the Thornwave PowerMon
for our use is we are only going to need to connect four wires, and this unplugs to make
things really easy to work with. We are going to be connecting the ground to terminal one,
the external shunt to terminals four and five, and the power -- the positive lead
to the battery to power the monitor -- to terminal eight. Terminal seven, by the way,
is for monitoring a second power bank, so yes this PowerMon can actually monitor two power banks.
So let's get a hold of this wire, I'll get some connectors
and some, some ring connectors and wires, cut these to length and get these prepared.
So there we go! We've just finished manufacturing our own little wiring harness here
with the appropriate wires and ring terminals. Just plug that in and go hook it up. All we
need to do is connect these wires. Again this is going to be chassis ground, these two are going
to the external shunt, and this one is going to the positive battery terminal. Once we have
all that connected we just need to screw this to the wall and we're ready to start testing.
So there we go! There's the battery monitor, and wired and connected to the shunt.
I apologize for the harsh lighting in here, the sun's getting low in the sky, but let's
go inside. We'll install the app on our phone and check out the information that this is delivering.
Now through the magic of YouTube time travel we've been using this for a few days, and you can see
here on the PowerMon app that comes free from Thornwave, you can see that we are connected to
our PowerMon which we have named Durango. You can see in the very top row there the model number,
our current signal which is an excellent -72 dBm, and it verifies that we are in fact connected.
Now the first and second rows are the voltage levels. Our battery bank is currently recording
13.938 volts and the second voltage would be for the second battery bank if in fact we had
one connected, which we do not. So you're just seeing the nominal voltage being picked up by the
PowerMon. Now the next two values are incredibly useful information. It shows our current in amps
and our power in watts. You can see that our net current at the moment is -0.76 amps. Now we are
using battery power for a number of things in the rig right now as I'm speaking to you, but we're
also connected on shore power and the solar panels are also sending juice to the batteries. Our net
discharge right now is 0.76 amps and our current power consumption is 10.58 watts. Now what I'm
going to do, I'm going to walk over here to our bathroom for a moment and show you what happens
when I increase the discharge on our batteries and the the reaction of the power monitor is
virtually instantaneous. What I'm going to do is I'm going to turn on the vent fan in our bathroom.
Now three ... watch what happens to the current and the power ... 3-2-1 ... on!
OK, and you can see our current discharge rate instantly jumped up to approximately
1.25 amps and our power consumption instantly jumped up to 17.whatever watts.
Now I'm going to turn the fan off again so you can see the instantaneous reaction.
3-2-1... and it's off, and you can see how our current and power dropped down just about to our
previous levels. Now the power meter, it shows that we have a cumulative -622 watt-hours
and the charge meter shows a cumulative -44.67 amp-hours. Now those are resettable, if I hold
either one of those values it'll ask me if I want to reset it. I'm going to say no in this case.
The internal temperature of the battery bank is 76ºF. Now the next row -- power
status -- that would be if we had a relay connected to the PowerMon, which we do not.
If we did have one connected we would be able to remotely turn the relay on or off right from here.
Our peak current level since we reset it was 4.94 amps. Again I can hold that down if I
want to reset it. I am not going to do so. It picks up the device time and device date
when you initially set this up, it picks it up from your mobile device and will
thereafter maintain its own date and time, and it shows that we've been using this PowerMon
now for four days, 21 hours and 56 minutes. Now up in the upper right hamburger menu, if I click
on that it'll show you the configuration. It'll show you the configuration range for the shunt.
There's where you see the "flip current sign". Now in fact I did connect that flow of current
backwards through the shunt, so by simply hitting that little toggle right there I can flip it in
the other direction so it all makes sense. It shows where the voltage source is coming from,
trigger on relay, all kinds of things, and this is where you can also set up the low voltage
disconnect, high voltage disconnect, over current disconnect, your battery fuel gauge
or your lithium iron phosphate charge manager, among other things. Now let's head on over to
our RV Whisper system and I'm going to show you what this looks like right now on RV Whisper.
You can see right down there, the -1% state of charge. That is information that's coming from our
Thornwave PowerMon. Now I have access to this from virtually anywhere in the world as long as I have
internet connectivity, so I don't have to be right at the rig to see what's going on here. Now if I
click on the -1% state of charge message right there I will open up the sensor for the Thornwave
PowerMon within RVWhisper. And here it is. You can see our battery, the same information that we
got from the Thornwave app. You can see that our batteries are at 13.9 volts, our current discharge
rate is 0.8 amps, and the battery temperature is 76ºF. Now here's our history graphing,
and this is something that the RV Whisper system actually adds to our setup here. I can change that
past three hours to any value I want. You can see the battery state of charge over time, and it is
consistent because we're of course on shore power at the moment. Our battery bank volts over time,
our battery current, charge or discharge in amps over time, our battery temperature over time,
the signal strength of the connection to the PowerMon from our RV Whisper over time,
cumulative amp hours over time, cumulative watt hours over time, battery run time remaining in
hours, and you can see it's consistent because I have never discharged the batteries yet.
That will change once it's gone through a few charge and discharge cycles.
Battery two voltage means nothing because we have nothing connected to our battery voltage two, and
here's our sensor status. You can see it dipped offline for a second or two every here and there,
and here's our seconds offline over time. Current alerts, we have received no alerts from the
system, but if I go into the alerts on RV Whisper I'll pull up where I already have an alert set
up for the PowerMon and that is "Battery voltage getting low". Now our Battle Born batteries have
a low voltage disconnect at 10 volts, and you can see what I've done is I've given myself a one-volt
threshold, a one-volt headroom so to speak, and if it is at 11 volts or less for five minutes or
longer it will send me a text message. I blacked out my phone number there for privacy concerns,
but it will send me a text message to let me know that the battery is getting low and I need to do
something about making sure that battery gets charged. Now if you missed our episode about RV
Whisper we did a complete video on this system, and I encourage you to check it out. We'll put
a link right here on the top of the screen so you can go back and learn more about RV Whisper.
So we hope that you've enjoyed checking out all the things that a wireless Bluetooth power
monitor like the Thornwave PowerMon can do for you and your RV life! If you like this episode it's
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