Review: Rekon 3 Nano Long Range FPV Drone – Powered by Single 18650 Battery

by Oscar
Published: Last Updated on

Imagine 15 mins flight time on a 3″ FPV drone using just a single 18650 Li-Ion cell. HGLRC and Dave_C collaborated and released a pre-built model – the Rekon 3 Nano Long Range FPV drone.

I actually attempted to build this from scratch a while back but with little success. It’s very picky about the choice of components and they are very tiny and hard to work with. The good news is that HGLRC is now offering this as a BNF (bind and fly) kit.

Where to Buy?

You can get the Rekon3 from:

You will also need a 18650 Li-Ion cell to fly the Rekon 3, ideally something with high discharge rate. The recommended battery is Sony VTC6, VTC5A also works but with slightly less capacity.

The Rekon 3 comes with the following accessories in the box:

Rekon 3 Features

The Rekon 3 is a light weight 3″ FPV drone designed around a single 18650 Lithium-Ion cell as its power source.

Making this work is quite remarkable because Li-Ion cells have very low discharge current for powering quadcopters, not to mention it’s only using one single cell. 

Rekon 3 nano long range fpv drone review

Notable features of the Rekon 3 are:

  • Compact and light weight, 63g without RX and battery
  • Powered by a 18650 battery, offers 15min flight time in ideal conditions
  • You can get some serious range with the 350mW VTX and Crossfire setup
  • You can configure Betaflight wirelessly using Speedybee App over WIFI, a built-in feature of the Zeus5 AIO F4 flight controller

Specification

  • Carbon fibre frame (NOT 3D printed)
  • Zeus5 F4 AIO 1-2S FC (Integrated 5A BLHeli_S ESC)
  • Zeus nano VTX (350mW) with dipole antenna
  • CADDX Nano ANT FPV Camera
  • Rekon 1202.5 11600KV motors
  • GEMFAN 3018 3 inch 2-blade propellers
  • Weight: 62.5g (without receiver), about 115g including battery and RX

DJI HD Version?

Only analog FPV system is available for now. I checked with HGLRC and they told me there is no plan of making DJI’s FPV system to work on this quad, because the voltage is simply too low (I guess you could use a step up regulator), and it’s a bit too heavy for this quad to handle.

GPS Module?

Due to the lack of UART on the Zeus5 AIO flight controller, GPS module is not supported out of the box. But you can try soldering it to the legs of the F4 processor if you insist :) Or swap the Zeus5 FC out to something with more UART’s.

The lightest GPS module is probably the NLRC TinyGPS.

Closer Look at the Rekon 3

A little bit of background. The Rekon 3 is basically using 1S ultralight build components (toothpicks):

  • 1202.5 11600KV motors
  • 3″ props
  • 1S Whoop style FC

People have been experimenting with 18650 cells on these builds for a number of years now, but it was only recently made popular by Dave_C with his unique frame design that uses a 18650 battery holder.

The other feature of the Rekon3 is using a separate VTX that offers decent range. It can give you over 1km to 1.5km along with Crossfire Nano receiver and high capacity of the Li-Ion cell.

What I have here is the PNP version which doesn’t come with a receiver. Out of the box the Rekon3 has a cable for connecting to Frsky receivers.

I am planning to use Crossfire, so I’d have to take the thing apart to solder the receiver to the FC. They use a lot of screws for the bottom cage.

Rekon 3 nano long range fpv drone take apart zeus5 fc esc

All the components are connected to the FC – an AIO whoop style board. There’s is no external BEC, capacitor or LC filter. In the original design, there was a 5V step up to power the VTX, however HGLRC told me they didn’t need it in the Rekon3.

It wasn’t easy soldering on the FC, I should have avoided the PNP version :)

Here’s the wiring / pinout diagram for the Zeus5 AIO F4 FC:

And the Zeus5 AIO FC doesn’t have a current sensor unfortunately, it would have been nice to see battery mAh usage.

I am mounting the Crossfire T-Immortal antenna on the rear arms like this.

Later I moved the antenna to the front of the quad, which is much better.

Rekon 3 nano long range fpv drone mounting crossfire rx antenna

The arms are very skinny (1.5mm thickness) and not the most durable frame. But there’s a 3D printed frame design on thingiverse, so you can go ahead and print replacement frames when it breaks: https://www.thingiverse.com/thing:4769576

Rekon 3 nano long range fpv drone 1202.5 motor 3" propeller

Motors are connected to the FC via connectors:

Beware of battery polarity before inserting or you could fry the FC. They mark this very clearly in the battery tray.

Many people tell me I should use a battery strap, but no, it doesn’t need one, the battery is not going anywhere.

FPV camera is well protected by the 3D printed mounting plates, I think it’s PETG.

Rekon 3 nano long range fpv drone camera

USB connector is easily accessible from the bottom. The bottom cage is also 3D printed in PETG.

Flight Performance

Here’s some flight footage (both FPV and LOS)

The Rekon3 is pretty light weight even with a single cell 18650 at 114 grams, but it doesn’t have much power at all and is quite slow. It hovers at 55% throttle, is just not meant for freestyle and acro. Imagine flying a tiny whoop with a 70% throttle cap, then add some more weight to it, that’s what it feels like.

Rekon 3 nano long range fpv drone weight

It can do some simple flips and rolls, but really it’s designed for cruising around.

The Rekon 3 could be a good training quad for beginners, because it’s small, not powerful and safe. It’s very quiet and stealthy, it doesn’t bother other people.

With that said the arms are very thin (1.5mm thick), so they are not made for crashing. It will take a few hits on grass because it’s light weight, but it won’t survive much abuse on concrete.

Flying with Li-ion 18650 in the Rekon 3, I have been told you can let the voltage to go down to 2.5V in order to use all the available capacity.

I know it goes against what we were taught, to land when the voltage reaches 3.5V, but that’s for LiPo. For Li-Ion it’s allowed to go lower, and because it’s under load, you are going to get some voltage sag especially for batteries of such low C-rating like Li-Ion cells. When you see 2.5V-2.6V and land, it’s going to recover to around 3.1V-3.3V (or even higher). Anyway, you should experiment with the battery you have, and determine what’s the minimum voltage you should land.

Surprisingly it flies okay even with some of my low performance 18650, like Panasonic NCR18650B, these have 6A discharge current only. I don’t get the full flight time though with these, because voltage drops way too low before it can be completely discharged. When voltage drops below 2.3-2.4V the quad will just drop out of the sky and you will lose video also, I think that’s the limit for the BEC on the FC.

HGLRC’s recommendation is to get the Sony VTC6 for best performance.

Video Issues

Flying the Rekon3 out of the box, I was randomly losing video. It appeared that the VTX restarts whenever I move throttle too quickly. I checked with HGLRC and they told me they didn’t have such issue in their testing. But another tester of the Rekon3 is also having the same issue and he was using the recommended Sony VTC6 battery.

To troubleshoot, I tried using a LiPo instead, no more video drop-out, so that points the issue to the power source.

Since they are not using a 5V step up voltage regulator, I decided to try adding one for powering the VTX. And guess what? That fixed the issue! No more VTX restarting, video was good the entire flight. This is the BEC I am using: https://oscarliang.com/product-rqbl

But I was getting a bit of interference which appears to be electrical noise, so I added a 10V 1000uF capacitor to the power. It didn’t completely clean up the noise, but it’s much better.

Optionally you can also try adding an LC filter in between the 5V BEC and VTX to further clean up the video feed: https://oscarliang.com/product-r24p

Rekon 3 Setup for First Flight

You will have to dig through the settings and configure it pretty much from scratch.

Out of the box, Betaflight and BLHeli settings are not optimized. Obvious things like voltage warning and minimum voltage should be set much lower (2.7V, 2.5V), but they were all left at default. And they should have flashed the ESC to 16.9 and use 48KHz PWM frequency which is more efficient, since this quad is all about flight time.

To give HGLRC some credit though, Bi-directional DShot and RPM filter are already setup, PID seems to be tuned out of the box as well and it flies alright. And SmartAudio works flawlessly for changing VTX channels and power.

Note that camera is NTSC so make sure to put OSD elements in the correct portion of the screen so they don’t get chopped off.

When attempting to flash the ESC to BLHeli_M (v16.9), the ESC’s somehow got bricked (not responding anymore) after a “Flash Failed” error. So I had to re-flash them via C2 interface and it was laborious. Sometimes when I “Read Setup” only two or three ESC show up, so it seems those ESC aren’t the most reliable in the world. Maybe just a bad unit I received.

And for some strange reason, it just doesn’t work well with 16.9 firmware, it randomly drops to the ground. I spent a whole day troubleshoot to no avail. Totally fine with 16.7 firmware (the version it comes with), that means I can’t run 48KHz and RPM filtering. But the other tester has no such issue, so that’s a weird one.

Update (27th May 2021) – Good News

I think the first Rekon3 I got from HGLRC was just faulty, so I got myself a brand new one from Banggood, and it flies MUCH BETTER!

Here’s some uncut flight footage from today with my new Rekon3:

I no longer get video loss during flight, so I didn’t add the 5V step up BEC this time, and didn’t use additional capacitor and LC filter since video is pretty clean.

But because of the lack of 5V step up BEC, VTX and FPV camera just turn off when battery voltage drops to 2.8V, so you have to land around 2.9V. It’s totally fine, but after you land, the battery voltage ends up at 3.3V -3.4V which means there’s still some unused capacity. With a 5V step up BEC, you can probably fly until 2.6V or even 2.5V, giving you an extra 2-minute flight time.

Anyway I am still getting almost 15 minutes of cruising time, so I am pretty happy without soldering the 5V BEC.

The Rekon3 has potential flying mid range (1.5km to 2km – about a mile), however the stock antenna is a huge bottleneck.

Video quality is pretty unreliable with the stock dipole antenna, I was getting lots of multipath interference and breakup as you saw in my first video. I replaced the stock VTX antenna with the TrueRC Singularity, it’s a light weight CP antenna, only 1.1g! And huge improvement to video quality. Buy here: https://oscarliang.com/product-feh0).

These are other cheaper options:

Leave a Comment

By using this form, you agree with the storage and handling of your data by this website. Note that all comments are held for moderation before appearing.

27 comments

Ludwig Brechter 10th August 2021 - 10:33 am

Hi Oscar,
I am also having problems with the Rekon3:
It is getting really hot, at 125°C video drops out and at 140°C the whole copter.
Can you please give me information, what Firmware the ESC is on and what settings are in BLHeli configurator?
Also a diff of Betaflight would be very helpful!
Here is a video of my problem: youtube.com/watch?v=Wrq0HBkUdwM
Thanks in advance, Ludwig.

Reply
Oscar 10th August 2021 - 6:49 pm

that looks like a battery issue, you should only use VTC5A or VTC6 as recommended. You can see the voltage sag is terrible, it shouldn’t sag below 3.6V when you full throttle when the battery is fully charged.

Reply
Ludwig Brechter 12th August 2021 - 11:11 am

Hi, I am using VTC5A. Battery was quite discharged in the video, problem also consists with higher voltage. I have one of the copters that came right from HGLRC at the beginning, the same that you have had problems with. Did you spot a difference between the “old (HGLRC)” and “new (Banggood)” one? Maybe less good FETs on the AIO?

Reply
Ludwig Brechter 16th August 2021 - 7:35 pm

Found the solution. Wrong Settings in BLHeli. Copied the correct ones from a new Banggood one.

Reply
James 22nd August 2021 - 4:19 am

If you’re reading this can you share the version and settings you used?

Ludwig Brechter 6th September 2021 - 11:48 am

Hi James, sorry for seeing it that late. You can contact me at ww.lbre.de, there I can send you the info.

Taner 19th September 2021 - 5:46 pm

Is any chance that you can share your finding with us ? Tried to find you on this site www lbre.de may be www libre.de with no luck

Minh 12th June 2021 - 3:03 pm

Please be careful, it’s really easy to break. Cheap and fake carbon fiber.

Reply
Max 10th June 2021 - 8:46 am

My drone keeps crashing after about two minutes. Came with the receiver mounted on top of the flight controller. The case was bend because it pushed the electronics together very strong. Moved the receiver to the front, next to the camera.

Updated Betaflight but it keeps crashing after two minutes.

Support is annoying.

Drone seems to have an MMU issue. It always flips over to the left site and crashes front first to the ground.

My assumption: Due to the mounting of the receiver on top of the flight controller there might be some micro cracks. If the flight controller gets hot the issue comes into play and the drone crashes.

The packaging of the drone is also a problem as there is no foam at top or bottom of the drone. This may cause additional stress to all components of the drone.

I was in contact to the support but they seem not to be interested in finding a solution. They only provided useless advices.

Great idea but expensive for the quality and service provided.

Reply
James 21st August 2021 - 11:55 pm

I think you are on to something. My flight controller was getting hot even before arming. I confirmed the WiFi IC was getting very hot (FC would get up to 70C just sitting on the bench), so I removed it with hot air. Under a magnification I could see a crack in it. I was then getting 2 minutes of hover time(FC got up to 130C before video cut out). I tried increasing the ESC deadtime to 120 with new firmware and now get up to 4 minutes of flight time. I’ll try replacing the FETs next.

Reply
Taner 19th September 2021 - 5:41 pm

James did you manage to fix it at the end ? Seems that I have the same overheating problem quad is arriving to 130C degree and video cuts off. I installed BlueJay esc firmware with deadtime 120 with slightly better results but still overheat and cuts off the video :(

Reply
Bad Raven 9th June 2021 - 6:31 pm

Quality as delivered from HGLRC was abysmal, Mine had one motor running reversed, 2mm hole props on 1.5mm shafts, atrocious and badly incomplete Betaflight set up, PID and prop balance induced due no shaft location bad judder, loose camera, dirt inside the camera lens, poor quality banded video image even when disarmed and motors off…………….. and its NOT cheap, is it!! (I bought the R-XSR version)

Bind and Fly? It’d be easier to start from scratch and build. I would have but could not source motors at the time. I am still waiting on motors for a home build.
The design idea is OK, but HGLRC should be ashamed at how they have dumped this on users, I can only assume in a panic over beating the clones to market.

Quite the worst quad I have been supplied EVER.

Reply
Jase 4th June 2021 - 11:12 am

First flight mine dropped from the sky after 4 mins. 2nd flight it dropped after 5 mins. Gets extremely hot. The props supplied don’t even fit the motor shaft and rely on the prop screws to hold the prop on. Extremely disappointed in the quality of this thing. Wish I’d cancelled my order. All I have now is a spare crossfire rx and some spare motors for another project.

Reply
Eb 27th May 2021 - 4:35 pm

Mine came without rpm filter. So i guess, Pids also are not tuned? Not sure about that…It wobbles even during idle.

Reply
Oscar 27th May 2021 - 9:54 pm

See my previous comment, i posted my PID there.

Reply
chris 13th May 2021 - 1:46 pm

stockwise on the Zeus5 the second uart is used for the wifi function. do a remapping in betaflight and get the second full uart one S5 and LED… so gps works. cons: VTX has to setup manually…

Reply
Alex 28th August 2021 - 10:15 pm

Hi . Tell me how to do this in the CLI? Thanks.

Reply
Dzmitry 1st September 2021 - 8:56 am

Hi there! I’d like to add GPS, but I am noob. Can you, please, give short manual how to make it? Thanks!

Reply
PC 11th May 2021 - 3:23 am

Thanks Oscar but these PIDs as same as Dave_C provided on thingiverse. Maybe mine 139g is too heavy…

Reply
Paul 10th May 2021 - 6:20 pm

There is a lighter GPS unit than the BN180, but I haven’t seen any reviews yet. The NamelessRX Tiny GPS is 1.6g (vs 4.9g)… pyrodrone.com/products/namelessrc-tiny-gps-module
Seems like it would be a good fit for NanoLongRange builds.

Reply
PC 10th May 2021 - 8:13 am

Can you share the PID tune values of Rekon3? I build my own 3D printed version with Hawkeye Firefly 4K DVR. There is total 139g. I have used PID values from Dave_c but seems like difficult to control. Finally, crash to the tree… Your flight video look like stable. I am not sure is it related to PID tune. Thanks.

Reply
Oscar 10th May 2021 - 9:38 am

Here’s the PID that came with the Rekon3, it’s by no mean perfect, but it flies alright:
set p_pitch = 100
set i_pitch = 50
set d_pitch = 70
set f_pitch = 125
set p_roll = 90
set i_roll = 45
set d_roll = 65
set f_roll = 125
set p_yaw = 65
set i_yaw = 20
set d_yaw = 0
set f_yaw = 125
save

Reply
Bad Raven 9th June 2021 - 6:57 pm

Mine came with three profiles set, with quite widely differing PID numbers, have you tried changing profile?

Reply
Marc Frank 10th May 2021 - 8:10 am

I’ve had two HGLRC Zeus25 boards in a row that had cold solder joints.
First the Gyro wasn’t detected.
Second broke the USB off.

Reply
Alloutofdonuts 26th April 2021 - 4:53 pm

This is a dream come true! Someone NEEDS to make a dji version tho. A stripped vista with a nebula nano cam? I’d tolerate the nano’s ‘light challenged’ characteristics for this. Maybe a 40a 2s pack?

Reply
Rizilla 24th April 2021 - 10:50 pm

Looking forward to your review! I have one of pre-order. Patiently waiting for the day its shipped lol (May 4th I think it is) anyway.. my question is which 18650s will work best for this apart from the 2 sony cells you already mentioned?
LG? Samsung?

Reply
Oscar 24th April 2021 - 11:45 pm

Check 18650 specs, I think this quad draws 7A-9A only when cruising, so most high discharge 18650 should be able to handle it (e.g. 20A discharge and higher). The two sony ones I mentioned have been tested to work though.

Reply