Micro Reverb Li-Ion Cruiser

By jdmkramer on Nov 10, 2019

26  737  20

I keep slowly refining my long range builds and packs and Lithium Ion keeps seeming more and more feasible for everything but my smallest quads. Granted, my favorite flying would be considered boring to most. Out of curiosity, I stuck a 2S HG2 on a toothpick and when that terribly mismatched setup flew for 12 minutes I knew it was time for a proper attempt at a 2S Li-Ion micro.

The entire build was picked around the HQ T4x2.5x2 props that have been sitting on my desk since they came out. They keep me thinking about smaller possibilities for long range quads. I poked around for a while looking for something, possible a 3" that could be modified to suit this prop. When I remembered there were 4" arms for the Micro Reverb it became the obvious choice. Motors were a tricky one. 4" T-mount is already odd, but I have almost no experience choosing micro motors. I may also run this build on a 3S 18650 and 3" tri-blades so I went with AMAX 1106 motors. (Another item that has been floating around in my imagination.)

I didn't set out to build a sub 250g craft but that's what I ended up with. Even after deciding on using my favorite components instead of saving weight. This little thing has all the features of my larger long range builds. (I guess other than a baro)

Hover tests finally happened at 2-3AM this morning, and I'm excited to see how it cruises. The sound of a light 4" biblade hovering was very promising. :)

Amax 1106 6300 w/ HQ T4x2.5x2 on 2S 3Ah Lg HG2 18650 Pack:

I've since upgraded the motors to Xing 1206 6500 and it can carry 21700 cells easily!

Photos

Part List

Frame

ImpulseRC Micro Reverb 4" Complete Frame Kit
Racedayquads.com
$39.89

Flight Controller

BrainFPV RADIX LI 20x20 Flight Controller w/ Graphical OSD
Racedayquads.com
$49.99

ESCs

Aikon AK32PIN 32Bit 35A 2-6S 20x20 4in1 ESC (40 builds)
Racedayquads.com
$58.99

Motors

4 x AMAX Inno 1106 6300Kv Micro Motor (3 builds)
Racedayquads.com
$51.96

Propellers

HQ Prop Durable T4x2.5 Bi-Blade 4" Prop 4 Pack (4 builds)
Racedayquads.com
$2.99

FPV Camera

RunCam Split Mini 2 Micro FPV Camera / HD DVR 1080P 60 FPS Recorder (M8 or M12 Lens) - Orange (79 builds)
Racedayquads.com
$69.99

FPV Transmitter

TBS Unify Pro 5G8 V3 (RP-SMA) (101 builds)
Team-blacksheep.com
$39.95

Antenna

AXII-U.FL 5.8 | (2 builds)
Truerc.ca
$11.99

Receiver

TBS Crossfire Nano RX Special Edition (6 builds)
Racedayquads.com
$34.99

Receiver

RDQ Micro M8N GLONASS GPS Module (37 builds)
Racedayquads.com
$15.99

Batteries

2 x LG HG2 18650 3000mAh 20A Battery (2 builds)
Imrbatteries.com
$10.98

Power Distribution

iFlight 2-8S Micro 5V or 12V BEC
Racedayquads.com
$4.78

Power Distribution

16AWG XT30 Pigtail w/ Capacitor
Racedayquads.com
$2.99

Misc Parts

JY242 Threadlocker - 10ml
Racedayquads.com
$5.99

Misc Parts

2S Balance Lead JST-XH 2S1P Balance Connector Male/Female Plug - 10 Pack
Racedayquads.com
$4.99

Misc Parts

Clear Heat Shrink Tubing 1ft - Choose Your Size (13, 20, 25, 80mm)25MM
Racedayquads.com
$3.50

Misc Parts

Multirotor Foam Landing Pad 4 Pack - Choose Your Color (2 builds)
Racedayquads.com
$2.99

Misc Parts

RDQ Micro LiPo Battery Strap V3 Upgraded Metal Buckle - 155mm (for 2-3" builds) (5 builds)
Racedayquads.com
$0.89

Misc Parts

XT30 Connector Male/Female Set (3 builds)
Racedayquads.com
$0.79
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Discussion

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topsfpv   12 days ago  

hi, radix li must use minimum 3s to power. how do you power it with just 2s?

Mr.M.   18 days ago  

Your build inspired me building a similar quad, I like your idea of a sub 250g long range 4". At the moment I'm trying to find out the best way of power distribution using an addditional BEC. I use a Talon F7 which has an onboard 5V 2A BEC , but I'm not shure if I can use it to power both the TBS Unify Pro V3 and the RunCam Split nano. There are several possibilities now, including to choose 5V or 12V from the additional BEC ...
So what would be best? How do you use the additional BEC on your Build?
THX & many greetings, Mathias

Wingspinner   25 days ago  
1

Nice build! Thanks for the writeup.

WRT motors, for endurance, low kv motors wth bigger props with low pitch are more effcent and provide the lmgest flght tmes than the alternatves Havng build a few of this size quad, ive found 1408 motors with as low of kv as you can fndmmldde"
offer plenty of power for this size and weght of a quad

Im puzzled at your use of packaged 18650 style LiPos though. Those batteries are the same technology as the batteries we all commnly use on rc models and therefore, minus the packagng have the same energy density However, add the packaging n and you suffer a rather large weight penality and a much lower energy density In other words, you should get a lot more flight time from a an equivalent "C" rating unpackaged RC type lipo of the same weight as your 18650 type batteries.

I couldnt tell if you were tracking mah on your OSD? Are those batteries truly putting out 3000mah?

Thanks again formthe solid writup!
Ron
WINGSPINNER

jdmkramer   24 days ago 

The pack in the video (and photos) is a 2S made from LG HG2 cells that have had many cycles of abuse, run down to 2.7 or even 2.5 at times. I pulled just over 2000 out of them before voltage was so low it literally fell out of the air. I've checked when charging and the numbers going back in are very close. The cells are supposed to have just under 3ah in them under normal use, which is probably nowhere near the 10-15 amps I'm constantly pulling from them. You're right about the trade off in with weight and energy density. I would like to do some tests next where I use a LiPo of similar weight, and see what sort of performance I can get. I'll be posting more on this build, but now I'm testing my lightweight build, a 3" diatone cube frame using the same amax 1106 I originally used on this build. 17 minutes of proper flying around my neighborhood today before hitting my 2.9v (per cell) low battery warning. I'm glad you are finding this interesting :)

jdmkramer   23 days ago 

I flew a RDQ 2S 2500mAh 5C LiPo designed for the X9D 2019 transmitter this morning. It weights exactly as much as my 2s packs within a couple grams. I was able to get just under 15 minutes of flight down to 3.3V in flight. The 5C (15A) rating kept me from punching it constantly. This thing is an incredibly good pack for comparing to Li-Ions. I have some Molicel P26A 2.6Ah packs to compare it to, the HG2 pack I flew for 17 (16 something on review) is pretty well abused. I'm curious how a fresh pack would compare.

Wingspinner   24 days ago  
1

wasnt thinking when the as post and should have written: while the 18650 li batteries are SMILAR technology to lipo, there is, supposedly between 20-30% more energy in a bare Li battery vs LiPo. However, the weight of all the packaging to keep the electrolyte from leaking out of the Li supposely more than makes up for the difference in energy dnsity when it comes to larger battery capacities. At least this is what ive read. Li are potentially less crash worthy also because they use liquid elctrolyte instead paste My apologies for the mistake but it would still be very usful to see data (like your total mah after a flight) that shows that premise to be wrong. THANKS!

jdmkramer   24 days ago 

I've been meaning to read a bit more about these Li-Ion cells, because the cases do seem quite durable compared to LiPo, but I've never given one a solid direct hit. Most of my larger packs are made from exposed cells in printed TPU rings, for simplicity and cooling. The worst I've dealt with is a broken solder joint from a crash. I'm really enjoying not having to worry about my packs nearly as much. I was terrible about leaving my LiPos charged and damaging them.

Levin   Nov 11, 2019  
1

Looks great, more inspiration on long range 4 inch always great. Curious about your motor choice, have you tried larger, maybe 1204 or even 1404? Do you think the build would benifit from that?

jdmkramer   Nov 12, 2019 

I do. I think I need larger motors but also high Kv. Anything you could recommend in 1404?

jdmkramer   28 days ago 

I upgraded to 1206 for now and got just the right boost. I will be switching to 1404 or similar soon, to carry 3S or larger cell 2S.

kfncolo   Nov 11, 2019  
1

Exactly along the lines of what I've been thinking of building. Keep us posted on flight times.

jdmkramer   28 days ago 

Flight times were impressive to me on 1106 with 18650 and I think 1206 with 21700 will do quite a bit better. I just posted some flight footage,

FrostedFPV   Nov 11, 2019  
1

isnt this setup very comparable to the new mavic mini? I havent done a lot of research but from the stuff i have seen it looks like a 4 inch quad with 2s 18650 battery.

jdmkramer   Nov 12, 2019 

That's very interesting and I never considered it. I'll be looking into the specs of some of these mini camera quads.

FrostedFPV   Nov 12, 2019 

yeah if this could achieve similiar flight times it would be a very capable long range quad.

jdmkramer   28 days ago 

Just added some flight footage.

IcarusIX   Nov 10, 2019  

super promising indeed, weight?

jdmkramer   Nov 10, 2019 

I forget exactly but definitely sub 250. I think it was 220something AUW.

IcarusIX   Nov 10, 2019 
1

remember when sub 250 was a miracle on 4 inch? actually idk, before fpv we were building 100g 4 inch quads with propsavers but with REAl real quads i mean. progress is insane. these tmounts and new props and boards arent too bad at all :D

jdmkramer   Nov 10, 2019 

Seriously. I put all the fancy bits in this thing, then after the hover I stuck it on the scale out of curiosity. Pleasantly surprised. The pack weighs about the same as the quad. I'm planning to do something similar but aiming for light weight, probably in 3" with that betafpv 20a toothpick board.

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