Checking Out Taranis


Unfortunately, you may have already pulled your lovely new toy from the box and at least turned it on, only to experience your first brush with Taranis heartattackus when nothing happened. If you haven’t figured it out already, the transmitter is normally shipped with the battery unplugged. Plug it in, and try it again. If any warning screens appear, press any button to clear them, and eventually you should be greeted with the lovely tones of: “Welcome to Traneeess.” Don’t worry about it. You can fix that later. If you’ve been down that road before you got here and have just found out about it, you have my sincere sympathy.

   Battery Charging Note

Lesson Objectives:

  • Charge the battery using the internal charger and a wall wart.
  • Calibrate the reading on the main TX screen to reflect the measured voltage of the battery.
  • Calibrate the transmitter itself to reflect the values of its individual components.


Step 1: Charge the Battery

Charging the battery in your Taranis can be either super-simple or merely simple, depending on which method you choose and whether or not you wish to use an alternate type of battery.

The original Taranis shipped with only an 800 mah battery, and the first thing that many folks did was to swap it out for something else. Viable alternatives include two and three cell LiPo’s, three cell LiFe’s (This one from Hobby King is especially popular.), and self-constructed packs of various cell sizes and types. The primary limitation seems to be whether or not it will fit into the back of the TX. Space is limited.

Because the Taranis now ships from most suppliers with a beautiful 2000 mah NiMh Low Self Discharge six cell pack, the stampede to change to an alternate battery has subsided somewhat. Feel free to switch if you like, but most of us are content to use the new 2000 mah pack. If you’re interested, Bruce at RC Model Reviews ( has an interesting, if somewhat dated, video called Battery Options for the FrSky Taranis ( ) that looks at what’s available and how to adapt them to your transmitter.

The first decision you have to make when charging the battery is to whether or not you’re going to use the supplied wall wart, plug it into the charging jack on the right side of the TX, and forget about it. This is the super-simple method, and is probably used by the greater majority of Taranis devotees. The built-in internal charging circuit charges the battery, senses when the charge is through (delta-peak method, I believe), and shuts down. No problem. However, there is a caution when doing this.

Because of the danger of fire, many folks recommend that you only charge batteries outside of the equipment case using an external charger. That way you can visually inspect what’s happening and observe the charging process closely the entire time. If there is excessive heat or some unexpected swelling of the batteries, you can jump in to prevent disaster.

Which method you use is up to you. Removing the battery is considered safer, and indeed mandatory for LiPo’s, but agreement for NiMh is not so unanimous. If you want to be super safe, remove the battery, build a charging adaptor cable to fit a 2S balance plug, and charge externally.  If you want the convenience that’s designed into the Taranis, use the wall wart and the internal charger.  Again, never plug an external charger into the charging jack of the Taranis. Note that the wall wart is NOT an external charger.  All it does is supply ~12vdc to the built-in internal charger inside the TX.

Because by far more users take advantage of the convenience of internal charging, we’ll deal with that method for the purposes of this lesson.

When you first connect the charger, the green LED on the back of the transmitter will blink for approximately 30 seconds then go to a steady ON state. This indicates that the battery is charging. When the battery is fully charged, the light goes OFF. I know, I know! That seems backwards, but that’s just the way it is.

Now, this thing isn’t a powerhouse charger, so depending upon the state of your battery, it may take a bit of time to reach fully charged. With the new high-capacity packs that Taranis now ships with, I’ve heard that eight hours isn’t unheard of, and perhaps even longer.

Battery Charging Checklist

  1. Watch all of Scott’s video on TX calibration: Basic Calibration on the Taranis (  Pay particular attention to what he says about saving and erasing calibration settings in the final few minutes of the video.  That concept is vital!
  2. Watch at least the first 7:30 of Scott’s video, What to do First When You Get Your Taranis.( It will set up the rest of the lesson.
  3. Check to see that you have the 2000 mah battery. It’s printed on the battery. That’s not essential by any means, but it’s a good thing to know.  Taranis 2000 milliamp battery
  4. Plug the wall wart into the wall, and the other end of the cord into the TX. It fits into a jack on the lower right corner of the case if you’re looking at the transmitter from the front.This is the wall wart that came with my TX.  It’s rated 120-240vac, 50-60Hz, 0.2a input, with a 12vdc, 0.5a output, with a positive center connector.  Yours may be slightly different, but should match the above numbers at least reasonably closely.wall_wartw
  5. Look at the back of the transmitter, and check out the small, green, blinking LED in the (now) lower left corner. Continue to stare intently. The more intense the stare, the more quickly the light will turn to a steady green that indicates the battery is charging.  Yeah, and about this bridge that I have for sale…..

Taranis Charging Light

  1. Past experience indicates that things will proceed according to schedule, however, you ARE charging an active device (the battery) inside the transmitter. In this case, common sense dictates that you remain at least within sight during the charge process. In the past, untold thousands of us (note the inclusive pronoun) have simply plugged things in and let them charge forever, However, I no longer follow that practice, nor can I recommend that you do so.
  2. Remember, the light goes off when the charging process is complete. A fully charged “hot off the charger” 6-cell NiMh pack can read as high as 8.4vdc.


Step 2: Calibrate the Onboard Voltage Reading

Does your transmitter have some kind of indication of the voltage available from your TX battery pack when it’s being used? If it does, are you sure that “7.5” is actually 7.5 vdc and not 7.3 or 7.6? Chances are you aren’t, because you’ve never been able to actually calibrate your particular battery so that the transmitter display shows you exactly what the battery voltage really is.  This becomes important because the Taranis uses this voltage to tell you when it’s safe to fly and when to land.  We’re going to ensure that what you see listed on the main transmitter screen is your actual battery voltage.

Look at your main transmitter screen.  In the upper left corner will be a value representing what Taranis thinks the voltage is of your transmitter battery.  However, without checking the calibration, you can’t be sure.  We must measure the voltage of the battery and then make sure that the Taranis reflects the same reading.

Before we do that, we have to do is to shut down the internal RF module.  The reason is that the output voltage of a battery drops when it’s being used (i.e.: “under load”).  We don’t have a convenient way to measure the actual output of our battery when it’s in the transmitter and the transmitter is turned on with the internal module activated.  Some folks using alternate battery packs have the option of measuring off an unused plug on the battery, but we’re using the stock unit and don’t have that option.  Therefore, the most convenient way for us to measure battery voltage is with the battery removed from the case.

Calibrating Your Battery Voltage Reading Checklist

Objective:  The Taranis display voltage must be set so that it displays the measured voltage from the battery, or the voltage you see in the TX won’t be correct. If it’s not adjusted, you can’t depend on it to be accurate.

To set displayed TX battery voltage:

  1. Charge your battery as you normally would.
  2. Remove the battery and use a voltmeter to measure the voltage between the two wires on the battery plug. Record the value! Re-install the battery into your TX.Charged Battery Reading 8.38 volts
    1. Turn on TX in normal mode and clear any warning screens.
    2. Look at your transmitter screen.  In the upper left corner will be a value representing what Taranis thinks the voltage is of your transmitter battery.
NOTE:  I'm currently using OpenTX v2.0.5.  The exact number of key presses in the following examples may be different, depending upon the version you have installed.
  1. To shut down the internal RF module and reduce the battery load:
    1. Short Press “MENU” to access “Model Selection” page.
    2. Short Press “PAGE” to access “Model Setup”
    3. Either press the “+” button 9 times or the “-” button 33 times to get to the “Internal RF Mode” setting.  In this instance, the internal RF module is on in D16 mode (Duplex 16 channel telemetry-the standard mode with the new X-series receivers).intRfOnw
    4. Press “ENT” to edit it.  It will begin flashing.
    5. Press the “-” key to highlight “OFF”intRfOffw
    6. Press “EXIT” to return to the main transmitter screen. (3 times in my case)
    7. Be certain to turn your RF module back on before attempting to fly!  The results can be rather disappointing if you don’t.
  2. OK, now that we’ve gotten the battery load reduced, we can calibrate the reading.
  3. Long Press Menu to enter “Radio Setup”
  4. Press “Page” 5 times until you get to the “Analog Inputs” screen. At the bottom of the screen, you’ll see, “Battery Calib” and a value. This value will vary depending upon the battery type you’re using and the current charge in the battery. The value should be highlighted. If it agrees with what the meter said, great! You’re done. If it doesn’t, continue onward to make it match the voltmeter reading.battprecalibw
  1. Press “ENT” to access the screen adjustment mode. Please note that nothing changes.  The value does NOT blink to show that it’s ready to be changed. Don’t let that throw you.
  2. Use the “+” and “-“ keys to raise/lower the displayed voltage until it agrees with your measured voltage. You probably won’t get it to agree exactly right now, but get it as close as you can. Don’t press too quickly or for some reason it doesn’t seem to be recorded. battadjustw
  1. Press “EXIT” (twice in my case) to return to your main transmitter screen. Note that the displayed voltage now agrees with your measured voltage. SUCCESS!
  2. TURN YOUR RF MODULE BACK ON!!  (Can I be any more direct?)
    1. Use the procedure outlined above to navigate to the “Internal RF Module” setting.
    2. Press “ENT” and then “+” to re-activate the module in the desired mode.
    3. Press “EXIT” to return to the main transmitter screen.


Step 3: Calibrating the Transmitter Sticks and Pots

It stands to reason that no two transmitters will have the exact same value of components installed. Oh, the numbers and printed values will be the same, but because over time they come from different manufacturers and different lot numbers, the actual value will differ. With most transmitters this isn’t much of a worry. You’re creating and trimming models only on that transmitter, and once things are set, you normally don’t have to worry about them.

I flew an Airtronics Stylus for years, as did several of my flying buddies. It had a “Glider Card” where you could store what we now call model profiles on the card. You could put your card into a buddy’s Stylus, and he could load your model’s profile. You’d have to completely re-trim, and in some cases even change the direction of servo throws, but that was understandable. You were using different physical models even if they were the same type (Paragon, Bird of Time, etc.).

Then one day my venerable Stylus experienced a case of forgetfulness (the internal battery on the board died!), and when I went to turn it on, it was deader than Mrs. O’Leary’s cow. A friend loaned me his Stylus to fly with for the day using my models. When I put my card into his transmitter and loaded my profiles, every single one of my trims was off! Why? As listed above, the values of the components in his radio differed from mine.

One of the greatest things about OpenTX is the ability to share model profiles across multiple platforms. You can send them to a friend, you can put them on your computer to work with, you can even create them on your computer and move them back to your transmitter. However, if you don’t have your transmitter calibrated, and those transmitter calibration numbers don’t match what you’re bringing in, you could be in trouble. You’ll learn much more about how to actually do all of that later on. For right now, let’s just get this puppy calibrated so that we don’t have to worry about it anymore.

Beginning at about 1:50 in his calibration video, Scott shows you how to get into Model Setup, then the Sticks Menu, then how to check and see if you’re controls are actually tracking.  He’s using an earlier version of OpenTX.  Note that if you already have some version of OpenTX2.x installed, the Sticks menu has become the “Inputs” screen. If you’d like, take time to do that, but at this point it’s more interesting than necessary.

Calibrating Your Taranis Checklist

  1. Turn on your transmitter and clear any warning screens.
  2. When you get to the main model screen, Long Press “MENU” to move to the Radio Setup screen.txsetupscrw
  3. Long Press “Page” to move backwards one screen to the “Calibration” screen.calibstartw
  4. Press “ENT” to begin the calibration process.stkcntr1w
  5. Center all controls (Sticks (remember the throttle!), pots, and sliders, then press “ENT” to move to the next page.stkcntr2w
  1. Move all sticks, pots, and sliders to their limits. Move them completely through their range, but there’s no need to slam them up against the stops. Track their progress on the calibration screen as you do so. Note that the bars move when the pots/sliders move, and the little open circle follows the sticks. My preference is to move everything back to the center when I’m done, but that’s not essential. If you’re used to doing this on a previous version of OpenTX, you might notice a slight difference in this screen. The four control indicators in the center of the screen now have a space between them. Pots on the left, sliders on the right. Neat!
  2. When finished, press “ENT”. Nothing happens…..well, actually, it does. You just can’t see it. The values that you just determined are stored in your transmitter, which is exactly what we wanted to have happen in the first place.
  3. Press “EXIT” until you return to the main transmitter screen.

Wrapping Things Up

OK, so what have you done so far? Well….

  1. You opened up the box and attempted to turn on the TX, only to discover that the battery wasn’t plugged in.
  2. You remedied that, turned the TX on, and were rewarded with the welcoming message from the Lady of the Box.
  3. You either charged the battery while it was installed in the TX using the approved wall wart charger, or removed the battery and charged it with an external charger then re-installed it.
  4. You’ve calibrated your transmitter battery readout to match a measured value.
  5. Finally, you established your individual transmitter end points for the sticks, pots, and sliders by completing the transmitter calibration routine.

Sounds as if you’re ready to start thinking about performing the final task that turns your Taranis into an even more powerful source for good in the RC world than it already is, installing the Developer’s version of OpenTX v2 on your Taranis. We’ll begin that phase of the journey in the next exercise, Intro to Zadig.


Checking Out Taranis — 16 Comments

  1. I am assuming the “Zadig” is a Windows based driver. Have I understood correctly?
    If so, is there an equivalent for Linux Mint? Or is one not required?

    Apologies for the beginners question.

    • Jim:

      We’re extremely short on Linux materials, I’m afraid. Your best bet might be to contact someone on one of the RC Groups. Perhaps there’s even a Linux dedicated group. I’m not sure if a special driver is required for Linux. Does Linux utilize a DFU? If so, perhaps one place to start your search. BTW, no apologies necessary!

      Leonard (mac44mag)

    • Hi, Neal, and welcome aboard!

      If you’re asking about using a 12vds/5a source as a charger for your Taranis, as long as the plug polarity is correct you should be OK. I’d be careful with it, though. Just watch out for overcharging.

      Leonard (mac44mag)

  2. A word of caution. I researched as well as I could about using the FrSky 7.4 Lipo in my new Taranis Plus. Based on that research I replaced my stock battery with the upgraded FrSky lipo.

    While charging the battery in the radio, the battery failed and the radio and battery were destroyed.

    Do NOT charge the FrSky lipo in the radio with the supplied charger!

  3. The first component after the charge socket on my Taranis Plus is a full wave rectifier this will rectify an AC supply to DC for the rest of the built in charger circuit. Is this different for the Taranis Mkl?

    • The AC adapter outputs 15VDC, not AC. The bridge rectifier can be used as reverse polarity protection in DC circuits. There is a small amount of efficiency loss in the diodes, but is a nice trade off for the added protection. I know this is a very old tread but I’m new and had to reply..

  4. I have a question regarding the battery calibration. Wouldn’t you want to leave the RF module on so that you calibrate the battery with conditions that it would experience while being used? Calibrating it without a load would give you a false reading as to when you are using it, would it not?

    • If I recall correctly, that’s been discussed on a couple of the forums with definite opinions on both sides. Theoretically, yes, the module will produce a load that will drop the actual voltage a bit, but many just don’t worry about it.

      Leonard (mac44mag)

    • No, you really DO want the RF module off. When you measured with the voltmeter, you had open circuit – no voltage drop. You recorded a value. Now you are trying to measure that same voltage using the internal circuitry, and you want it to match the recorded value. If the RF module is on, it drops the battery voltage that which the internal circuit sees. You can see the effect by looking at the main screen. Since the resolution is only 0.1 V you may not see the drop… but you might. For me, right now, the open-circuit voltage was 8.38. The main screen shows 8.4 with the RF off, and 8.3 with the RF on.

      Does it matter? I doubt it! Just make sire the battery warning is below that – mine was set for 9.x volt in the Taranis as delivered, with a 7.2V battery module installed 🙂

    • The voltage at the battery terminals is being measured. So for accurate calibration, do it with as high a voltage as possible, whether on load or off load doesn’t matter as long as the battery is fully charged, what is important is that the calibration voltage is measured at the same time as the Taranis voltage readout is adjusted. This means applying the test meter leads to the battery at the same time as operating the Taranis and setting the voltage reading to the same as that on the test meter. This would be best done with a Y lead pluged into the Taranis battery connector. Is it worth all the trouble? I certainly don’t think so, I charged my battery, checked the voltage, pluged it into my Taranis plus, switched on and as quickly as I could set the voltage reading to the same. This could be up to 0.1V high for the battery voltage initially was falling quickly (whilst the surface charge is dissipating).

      • Its not so much the value being high or low as it being measured under the same conditions both times. Once with an external voltmeter and once by the internal circuitry. The more load you have a battery under the lower its output voltage will be but the change is dependent on a bunch of stuff. Since we are trying to calibrate the internal voltage sensing circuit the ideal would be to measure it with a known good meter under the same load conditions as when the internal circuit is measuring it. The battery that comes with the radio does not have extra leads for measuring the voltage while the radio is turned on and under load. The best we can do is measure it with with an external meter under no load conditions and then minimize the load when the battery is plugged into the radio. Hence the radio transmission circuitry is turned off. Then display will still be a bit off but since it only resolves to 1 decimal it should be “good enough”. The important thing is that we want the radio to warn us BEFORE it shuts down due to low battery so that we have enough time to do something about it, such as land the aircraft.

    • OOPS! Sorry about that! I changed the page a week or so ago and thought I’d nailed all of the links, but I apparently missed this one. Try it now. It should work.

      Thanks for letting us know!

      Leonard (mac44mag)

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