Good day! When was the last time you calibrated your battery voltage and
current sensors in Betaflight? Did you know by doing so you could actually gain
some flight time and maybe save a few bucks too?
In today's video, I'm gonna show you how to do both in just a few short minutes
so you can have accurate battery voltage and current capacity used displayed in
your OSD which will allow you to fly longer yet at the same time preserve
the lifespan of your batteries. As a BONUS, I'll show you how to set up audio
warnings in your transmitter for both the battery voltage and current capacity
used (if you'd like) so you don't even have to watch your OSD while in
flight. Sound good? Then give it a "thumbs up" below, share
this video with your friends, and subscribe to your TMac FPV channel -
your home for YOUR "Journey to Better" FPV fun, flight, and racing stuff! First, we're
going to calibrate our voltage. These are the tools we're going to need. Of course,
since we're talking about Betaflight voltage and current sensor calibration
we're going to need Betaflight, but we're also going to need our quadcopter,
a LiPo battery, and either a multimeter or a voltage checker alarm - both of which
are available through links below as well as my recommended LiPos for micro
quads. Now, if you're going to use a multimeter, the way you use this is
with the battery connected to your quadcopter you would want to touch the
multimeter leads to the negative and positive pads of your ESC to check what
the voltage is of the battery while it's connected to the quad. For our case, we're
just going to touch the negative and positive leads to the XT 30, and in doing
so, our multimeter is going to read 16.36 volts. So keep
that in mind because now what we're going to do is we're going to use this
voltage checker alarm. We're going to insert the pins of this into the
balance lead. Remember "multimeter" said 16.36 and this is
going to show 16.4. So it rounds up to the
nearest tenth of a volt. So this is accurate as well. Now on this you can
also push this little button to set what voltage you want per cell for it to go
off at. So in this case I've set it to 3.3. S when the cell
voltage drops below 3.3 volts (or at 3.3 volts)
these beepers are going to go off. You can use this as a voltage alarm when
attached to your mini quad simply by connecting it to the balance lead of
your LiPo, as I've got here, while this xt 30 or xt60 connector is attached as
the power source for your quadcopter. It's just another voltage checker alarm
that you can mount on your quadcopter which will beep and give you a heads up
when to land. As I mentioned, the voltage checker alarm and the multimeter, as
well as my recommended LiPos for micro quads, will be down in the links in the
video description below. Now, of course, to calibrate our voltage
we're going to need to connect our quadcopter to Betaflight but before we
do I wanted to point out two things - 1. my props are off. Anytime you power up
your quadcopter inside (indoors) you want to make sure your props are off - whether
it's via battery or through connection to Betaflight. 2nd thing I wanted to
show you is, normally what I do when I power up my quad, in order to keep from
overheating the components (specifically the VTX)
is I've got this clip-on fan which I just clip on to the edge of the desk and
turn on to get some cool air blowing at the quadcopter components. That way
when I turn it on to connect to Betaflight (you can see the lights flashing-
it's on now) the components will have less of a chance to overheat with a fan
blowing on it. Now what we're going to do is we're going to go to our Power and
Battery Tab of Betaflight. We're going to connect the battery to the quadcopter.
Here you can see that Betaflight's showing the battery voltage is
14.04 volts and here's our scale. This is the value we're gonna
change. I'm gonna connect this little voltage checker alarm to the balance
lead of the battery like we did previously. It's a lot simpler and a lot
cheaper than a multimeter. Here you can see it says 16.3 volts
but over here our voltage is reading 14.03. So Betaflight
at this time thinks it's time to land our quadcopter at 14 volts
basically when we're actually showing 16.2 volts on our LiPo. So,
what we need to do is we need to change the scale and we're gonna do it at
increments of five at a time. So I'm going to change this to 100 then click
Save and watch this number up here.
14.76. Not enough. Let's go up to 110. Save. 16.23.
What are we showing? We are showing here 16.2. So right
there is probably pretty good. Let's go down to 109 and see what happens.
16.1 That's probably as close as we're gonna get. So we've changed our
scale from 95 to 109 and we've hit save. Now our voltage meter in Betaflight
is calibrated to our battery which will allow us to accurately fly the maximum
amount of time while at the same time preserving the useful battery life so
that we don't have to spend additional money needlessly buying more batteries.
Next we'll calibrate our Betaflight current sensor. Now we're going to
calibrate our Betaflight virtual current sensor which uses the throttle
position to calculate an estimated current value. To do so we're gonna go to
this github.com Betaflight site using this URL. I'm
going to scroll down to "tuning using battery charger measurement" and we're
going to use this process (to include this equation) which I'll
demonstrate here shortly. Before we do this, we need to go to our Betaflight
OSD and make sure that we've got our battery current milliamp hours drawn
(which is the total battery capacity used) toggled on for our OSD profile that
we're going to be using. Normally I place the milliamp hours used, as well as the
battery voltage, in the lower right hand corner of my OSD screen. For the purposes
of this video I'm going to put them right in the middle of my screen just so
it's completely obvious to everyone what we're looking at. So this is the battery
voltage which we just calibrated and this is the value Betaflight believes
is the milliamp hours used of our battery which we'll use in that equation
we just saw. So once we've toggled these on we're gonna click Save. Now we just
need to go fly and at the end of our flight (regardless of how long we fly)
we're going to take note of this value (milliamp hours used) at the end of our
flight and write it down so that we don't forget it. Alright before a flight,
we also need to make sure that we toggle on under post flight statistics the
battery milliamp hour used which is what we use to calibrate our virtual current
meter. While we're here I'll also toggle on "battery voltage end." We need to
click Save. Now I'll go fly a pack and show you what current capacity we used according
to Betaflight by looking at our post flight statistics prior to us doing our
calibration. That number is one of the three values we'll use to do our
calibration. All right let's do it. Alright here we're starting off with a
fully charged battery and you can already see the current sensor is way
off. Then towards the end of our flight see we're using over 6,400 milliamp
hours and we stop with the reading at 6685. So we'll use that as our second of
three numbers in our calculations. Now what we want to do is charge this
4S 750 mA LiPo battery which we just used in our flight using our
balance charger. 4S. I've got it set at 700 milliamp hours just because the
next jump up is 800 and I want to use no more than 1C
capacity charging. So we'll connect this to the balance board. We'll start charging
and we want to watch this number at the bottom when it's fully charged and that
will show us how many milliamp hours were put back in to the LiPO. So
when this is fully charged, it should read 16.8 volts. It'll
stop at that automatically with this charger. As you can see, the milliamp
values are going up so we'll take a look at that when this is fully charged and
that will be our third of three numbers that we need for our calculation. All
right our LiPo is fully charged at 16.8 volts and these are
the milliamp hours that we put back into it - 614. This is
the third of the three numbers that we need for our calculation. So it's time to
crunch our numbers and calibrate our virtual current meter. Going back to our
power and battery tab we see that our original scale was at 176 and that's the
first number we needed for our calculation.
So when crunching the numbers we're using this equation. Now remember earlier on in
the video, I mentioned that the numerator and denominator on the Betaflight site
were incorrect for Betaflight because they were actually using Cleanflight
and I believe Cleanflight might have been different than what we're currently
using for Betaflight. So this is the correct equation to use. We plug the
three numbers in our original scale - our milliamp hours used per our OSD display
and our post flight statistics, and then also the milliamp hours put back into
the LiPo via our charger. Plugging those numbers into this equation we get our
new scale number is 176 times this value 6685 divided by 614. Our new scale
comes out to be 1916 whereas our old scale was 176. So we take
this 1916 and we input that into our Betaflight "Power and Battery Tab" as our
scale number. Let's go ahead and do that. Now with our quadcopter connected to
Betaflight, we go back to our "Power and
Battery" Tab and insert our new scale. Our old scale is 176, our new scale is 1916.
We just type in 1916, hit save and we should be good to go! Now if you want to
get really accurate you could repeat this process with another battery to
check the accuracy of it and to refine the value as needed. The more often you
do this process the more accurate your values are gonna be, but remember, you'll
want to calibrate both your voltage and your current meters in Betaflight
before your first flight of your brand new bind-and-fly quad or before your
first flight of the new quad that you just built yourself. Now you've got your
battery voltage and milliamp hours used calibrated with accurate values
displayed in your OSD, but I promised you at the beginning a Bonus - showing you
how to set up audio warnings in your transmitter for both battery voltage and
current capacity used (if you'd like) so you don't even have to watch your OSD
while in flight. To implement this you need to go to these two screens - Logical
Switches and Special Functions on your transmitter "Model Setup" menu. You'll need
to get the telemetry values for your specific receiver that indicate battery
voltage and current capacity used. In my case with Crossfire it's RxBt and Capa
or C -A-P-A. You need to create two logical switch lines as I've done here with L3
and L4. I'm using 14 volts as my warning value for low battery voltage which for
my 4S LiPos is 3.5 volts per cell. This current capacity warning
value will need to vary based on the capacity of the battery you use. For
example, when I use that 750 milliamp battery a good warning value might be
600 or 80% of the 750. I've also got a 1.5 second delay setup which means
the actual value for my low voltage warning needs to be below this threshold
warning value for at least 1.5 seconds before it triggers this low voltage
warning switch. Then you need to make two "special functions" - one for each logical
switch (voltage and current capacity used) as indicated here. I've chosen to play a
sound track should my voltage get too low or my current capacity used get too
high. The sound track I've chosen to play is a custom one I made using
the process I described in this video "Jumper T16 Custom Sounds. I'll provide a
link to that video also in the video description below. So now you have
accurate voltage and virtual current sensor readings in your OSD and also
audible warnings in your transmitter. With that information you can rest assured
you have maximum flight time while also preserving your batteries'
life which will save you money in the long run. If you found this video useful
make sure to share it with your friends, and head on over to the TMacFPV.com
site where you can find more free resources, the Diamondback Rattler in the
Pilots' Den Page, and the Fast Track FPV Course - YOUR Clear Flight Path to FPVFun!
Thanks for your time, I'll see you next video.
Clear skies friend!