Tech Stuff & Reviews

Review: Full Speed Leader 120 Mini FPV Racer

Mike vom Mars Blog fpv racer fpv racing full speed leader 120 kingkong 90gt leader 120 leader 120 mods leader120 led strip mini fpv racer qx 95 racerstar runcam micro swift vtx03
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Full Speed Leader 120 Lipo Comparison

Page 1: Review
Page 2: Modding
Page 3: Betaflight
Page 4: Lipo Comparison
Page 5: Videos

Leader 120 & Accessories:
Leader 120 Mini FPV Racer
VTX03 25 / 50 / 200mW Mini VTX
Runcam Micro Swift 2
Mini LED Strip
FrSky XM+ SBUS Receiver 16 Channel
Kingkong 2840 2.8X4 3-Blade Propeller
Gemfan 3025 2-Blade Propeller

Leader 120 Lipo Comparison

Which battery weight is ideal for the Leader 120? We have tested the most common 2S and 3S lipos to find the ideal battery weight for the Leader 120, which allows you to fly as long, but also as agile as possible.

Of course, the flight time depends on your personal flying style. In our tests we flew quite fast and with a good use of the throttle stick. In every flight and with every battery we performed many loops, flips and punches. The flight times we received can thus be significantly extended if you fly in a relaxed and smooth manner. If you don’t accelerate too much, you could easily add 1-2 minutes to the flight times for each result in the following table:

Leader 120 Lipo Comparison
Lipo:C-Rate:Weight:Flying Time:Feeling:
2S Tattu 450mAh75C29g3:00feathery
2S Tattu 650mAh74C38g4:00very manoeuvrable
2S Tattu 800mAh45C43g5:20quite manoeuvrable
2S Nano Tech 850mAh25C49g5:40quite very manoeuvrable
3S Tattu 450mAh75C43g3:40feathery
3S Tattu 650mAh75C54g4:30very manoeuvrable
3S Tattu 850mAh75C86g4:30noticeable weight
3S Floureon 1000mAh20C83g4:30noticeable weight


2S batteries for the Leader 120 should preferably not weigh more than 50g. The more capacity (mAh) you get below this weight, the better. According to our test, the discharge rate (C-rate) has less influence on the Leader’s flight behaviour.

3S batteries are allowed to carry a little more weight, as they provide more motor power due to the higher voltage rating. Nevertheless, our test shows that the limit is reached at about 55g. Above that, you feel the additional weight on your sticks. Everything underneath flies great. The ideal 3S battery for the Leader 120 has a maximum of 55g on the scale, but with as much mAh as possible to ensure a good flight time.

By the way, we also found that a Lipo can be too light of weight instead of too heavy. When flying the 2S 450mAh battery (only 29g) the Leader was so lightweight that it literally sucked itself into the air and didn’t want to come down again. This makes some manoeuvres quite difficult, because you can’t use the racer’s weight if you want to quickly lose some altitude. With a too light battery, it’s hard to do this – you literally feel like you’re standing in the air.

The ideal candidates are therefore:

Best 2S Lipo

Reach for the Tattu 2S 800mAh. This one comes with an ideal weight and allows an acceptable flight time. If you only want to spend half the money, you’ll even get 50 mAh more capacity (but also a few grams more weight) by choosing the HobbyKing Nano-Tech 2S 850mAh. It offers “only” 25C, but there is no earth-shattering difference between the Nano-Tech 850 and the Tattu 800. Both are great 2S lipos for the Leader (and most other mini quads as well). With a Nano-Tech 850 we have even set a flight time record with the Leader: more than 8 minutes! However, this is only possible if you fly very relaxed and without any full throttle. Then it turns out that you can get a lot out of 850mAh.

Best 3S Lipo

Among the tested 3S batteries, the Tattu 3S 650mAh is the best choice. It is lightweighted enough to fly beautifully agile but also offers enough capacity for at least 4.5 minutes of flight time. With a relaxed flight maybe 1-2 minutes more.

The 850mAh Tattu doesn’t deliver a good result, because it comes with XT60 connectors and quite thick cables and therefore simply puts too much weight on the scales. In out test, the flight time did not increase beyond 55g of battery weight. The weight eats up any additional capacity then.

The two best 2S lipos come with JST plugs. So if you plan to fly 2S only with the Leader, you don’t have to change the battery plug, because the Leader is already equipped with a JST plug. The 3S Tattu comes with an XT30 connector. So if you want to fly 3S, you have to replace the Leader’s plug with an XT30 or a DIY adapter plug.

Those who prefer to fly more comfortably and are looking for longer flight times should choose 2S 800mAh lipos, such as the Nano-Tech from HobbyKing. With the 3S 650mAh the Leader 120 flies really wild and can be punched neatly. Power, speed and weight are very impressive here, but with shorter flight times compared to the 2S 800mAh.

Next page: Leader 120 flight videos

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Editor rating: 4.7 / 5

Recent Comments

  1. Hey – great review and write-up. Great for noobs like me! I am struggling to find the Nano-tech 2S 850mAh batteries that weigh 49g though… the ones on the Hobbyking site are listed as 95g. Did they used to make a lower C rated version that was lighter?

  2. Paul, see here: – 95g is the brutto weight. Netto weight is 49g (just the lipo with the cable), it's written in the description below there.

  3. Doh! I was ordering the battery list by weight:)

    Thanks, I'll get a few of those ordered

  4. Will these settings work for a Frsky R-XSR receiver? I can't seem to get my TAranis talking to my receiver.


  5. I am using FrSky XM+ with all my micro quads since it is tiny and has full range, plus RSSI. That's all you need while flying with goggles. So I don't know about R-XSR, I'm sorry. There could be several issues: make sure you activated the correct UART in Betaflight and plugged the receiver to the correct pins on the FC. Protocol in Betaflight should be set to SBUS, too. That's the main things to do.

  6. Thanks for that excellent Review!

    Are the props suggestion for 2S -3Blade 2840 and for 3S 3025? …besides the originals draw to much amps and seem not available.
    Are there further alternatives?

  7. I am using the original props (with 2S and 3S) and they do very well so far. Motors don't get hot (not even warm) with them. However, some Leader owners complain about blackouts or reboots that may happen if the FC board cannot provide enough power for the VTX, RX, LED etc. This seems to be the case if a 200mW VTX is used (which draws more power than the FC's cheap 5V converter can handle). If this is the case, I'd just install a little 5V BEC (Matek, f.e.) that is directly plugged to the battery and powers the VTX, RX and LED. That should provide more stable 5V than the built in converter of the FC board.

  8. Looking to buy the Flightcontroller that came with the leader 120
    fired mind but everything is ok so need the FC .Anyone know were I can get and what is the Flightcontroller I need to purchase
    Thanks a lot
    Love this write up

  9. Generally you should be able to use any F3 / F4 board that fits the frame's screw holes (20x20mm mounting hole distance), so you could chose one that fits your taste. Or even upgrade to a F4.

    This one looks very similar though:

    Or drop an email to Full Speed and ask them about spare parts.

  10. Thanks for the reply
    I am new at this, the one thing I am confuse with is how to power the FC how do you know were 12v is

  11. @David – I am not sure what you mean with 12V, so here's a general guide:

    Most FC's have a VBAT pin. The VBAT pin is used to power the FC directly from the battery (2S-3S for example, depending on the FC's specs). To power a FC, just connect it's VBAT and VBAT GND directly to the battery contacts -or- to the VBAT / VBAT GND pins of the PCB board.

    Some FC's cannot handle full VBAT power. They are powered by 5V only. Then you have to use a power board that provides a 5V output for the FC. The Leader FC (and many other F3 FC's) should be able to handle full VBAT, however. "VBAT" always means full battery power as it comes from the Lipo.

    Once the FC is powered, it reduces the full VBAT voltage to 5V (using an on-board module, called LDO) and sends the reduced 5V to all the 5V pins found on the FC board. All these 5V pins on the FC are called the "5V rail". These 5V pins on the FC can then be used to power the camera, VTX or an LED strip. You should keep the number of devices connected to the FC's 5V rail to a minimum, otherwise the FC might get too hot or won't be able to provide enough Ampere for all that devices.

    So if your camera or VTX can handle VBAT (full battery voltage), you should connect them to the battery directly to reduce the power load of the FC. Most cams (such as Runcam etc.) and VTX can handle full battery power nowadays.

  12. Hi, kannst du mir sagen wie das Update von Betaflight vonstatten geht? Muss man einen dieser USB Treiber installieren?

  13. @Martin: falls dein Kopter über USB nicht von Betaflight erkannt wird, gibt es zwei Tools, die dir den USB-Treiber installieren: das eine heisst "Zadig", das andere "ImpulseRC Driver Fixer" (Google-Suche). Damit sollte der USB Treiber dann installiert sein. Hier ein Video dazu:

    Das Update selbst geht dann über die Betaflight App. Diese App musst du im Chrome Browser installieren (Chrome starten, suche nach "Betaflight App" und diese installieren).

    Wie man dann in Betaflight updatet, zeigen viele Videos auf YouTube, z.B. hier:

    Ist am Anfang recht viel zu lernen, ich weiss. Aber da muss man leider durch ?

  14. Hi Mike, danke für die schnelle Antwort! Der Driver Fixer hat mir weitergeholfen und BF auf den neuesten Stand gebracht!

  15. Hi Mike. Toller Artikel, danke dafür. Leider bekomme ich die Kiste nicht mit meiner QX7 gebunden. Der FrSky Receiver XM+ mit EU/LBT Firmware sollte richtig verkabelt sein. Taranis steht auf D16 Modus. Wenn ich binde, leuchten die rote und grüne LED am Receiver. Nehme ich den Strom weg und wieder dran, leuchtet nur die rote und nicts tut sich :(
    Hast du ein paar Tips für mich?

  16. @Michael: bist du dir sicher, das die passende Firmware auf dem Empfänger installiert ist? Ich gehe immer so vor (allerdings mit der Devo 10, nicht der Taranis):

    1. Funke an
    2. Bind Button am Empfänger drücken, Akku anschliessen.
    3. Funke in den Bindemodus schalten
    4. Nach dem Binden Funke und Empfänger ausschalten
    5. Dann beide wieder einschalten, die sollten sich dann automatisch finden.

  17. Jo, ich tausche Punkt 2 und 3. Ansonsten mach ich das auch so. Hat auch bis jetzt immer geklappt. Nur bei meinem Leader nicht. Ich denke auch es ist ein Versions Problem. Ich muß mich mal in das Firmware flashen Thema einlesen.

  18. Kurze Rückmeldung nach dem flashen des XM+. Es lag tatsächlich an der falschen Firmware. Vielen Dank für deine Hilfe.

  19. Hallo Mike,

    Auf dem Wiring diagramm steht unten rechts 5v+, bei mir ist dort dort aber vbat angeschlossen. Ist das Diagramm falsch?

    Grüße Steffen

  20. Hi Mike,

    I bought the Leader 120 based on your review and I'm loving it. I'm using an FrSky R-XSR without any problems. However, I miss the FrSky telemetry and spoken battery alarm I have on my bigger quad. Do you know if the TX1 or TX2 pins on the FC can be used for Telemetry? I'd try it but I'm still quite new at this and have damaged enough electronics through ignorance to be worried about trying it without a good idea it might work.


  21. @Peter: I don't use Taranis myself, so I can't help you with this. I am using the Devo10 and FrSky XM+ with all my micro quads. The XM+ receiver has RSSI, which can be displayed in the goggle's OSD, as well as the voltage and mah consumption, so (in my opinion) there is no need for Taranis telemetry anymore in the days of Betaflight OSD.

  22. Hello, friend! Is it possible to set up a beeper to search for a quadcopter? I tried to set up a betaflight nothing happens..((

  23. Why the Max Vel Deg/s of yaw is bigger, despite the rates of pitch, roll and yaw are equal?

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