Can you give us a quick hint? Don’t need step by step instructions, but what is it that you did?
20A Hakrc ESC is good and economic
this?
Alberto_Ds and to wicked1:
sorry for the late reply, very bussy days for me 
yes, this one i mean. very friendly and helpfull.
check the comments, everything is there and im not good at explaining.
to share with the community i made videos, i hate to keep stuff for me alone.
i still need to upload videos of my summer work, i made a 7gr. only HD/FPV Camera looking like caddx tarsier for my micro copter’s. now it is winter in germany and i will find more time, i hope so.
Thanks,
I see it in the comments now.
Time to get out the magnifying glass and soldering iron :).
From what i read to discharge li ion to such low voltage Is not a problem as with lipo. Anyway to go below 3V get you less cycle and shorten the Life of the battery, what are your experiences about this?
I used some Samsung 3000mAh Li-Ion, that can go down to 2.5V.
My flighttime is 20-22 Minutes wen Voltage is at 3V each Cell and i did not cruise very slow or just hold…i pushed Throttle 60-70%, Powerloop and just Fly like i want.
(Upload later a Flight Video i made some Weeks ago)
The lasting 0.5V bring only 5-7 Minutes more and you feel the Power dropping, i need ca. 10% more Throttle the last Minutes.
I used some old trash Parts i had laying around, my Copter was a bit heavy (190gr.) but new Batterys.
For me the last 0.5V each Cell will be some Backup Power i can use, i plan to Fly the Battery down to 3V normaly.
So it is important for me that the ESC can do this, most ESC shut down at 3.2V or like Airbot Ori 3.5V per Cell.
I do not Test other Li-Ion Brands, i used the same for my Fatshark Googles and they were just here.
Im not worried about Lifetime, one 3000mAh Li-Ion cost me 3€, so a 2s Li-Ion 3000mAh is only 6€.
For that Price i not get a GNB 450mAh 2s Lipo. So if the Lifecycle will be lets say only 100 Times (Flighttime only 20min per Flight = 2000 Minutes = 33 Hour fun), im very fine with that. But Li-Ion will hold way longer. I also do not need a Lipo Safe and allways check Voltage, so no explosions here 
Now after a lot testing, i start to buy all the Parts to build a fresh Copter.
I also did some Motor/Propeller Thrust Test, i printed for this a Thrust Tester and build it together.
Hope Banggood will deliver fast, 1-2 Weeks and i have everything.
But im unable to fly, as it is very cold in Germany…so i had to wait some Months.
Im sure meanwhile we all can find out how to set up arducopter on 3Inch 
I’ve been using liion, too. The ak32 esc I’m using will let me go down to 5.2v. But, my voltage does sag, so after I land, the voltage is still over 3v per cell. And the ESC is heavy. So, I’ve got a couple new ones on the way to modify and test.
AfriCopta, winters are quite cold here in the US Midwest, too. I sit on my warm couch and fly from inside. Or from in my heated car. Flying while it’s snowing is one of my favorite times to fly… If it’s cold enough, the snow just blows over the copter and nothing gets wet. I got one of the .0001 lux cameras so can fly by the light of street lights, and it looks like daylight.
I set my batteries on a heating pad as I charge them, so they’re warm for the flight. The voltage still sags a lot as they cool off, but it has not been a problem. The capacity is the same… just lower voltage.
About the ESC mod…
Did you have to do a similar mod to the FC so it can run below 5v?
It seems like the ESC only needs 3v for its components to run properly… But the FC is powering the GPS and other components that need 5v. So, maybe an external boost/buck regulator is needed for the FC? Like I said above, I’m going down to 5.2v and that has been fine w/ the omnibus nano board. But below 5v probably isn’t possible.
That sound very cool and i would love to see some snow here.
The last Time i remember we had a bit snow is more then 10 years ago, only wen i was a child there was really big snow for weeks in germany. Only at some local spaces now there is snow
It is only wet, ugly, windy and cold.
To your Question, if you fly down the Li-Ion to 2.5V each Cell you should be fine with 5V.
The ESC give to the FC the voltage directly from the Battery, im sure there is some BEC on the FC to hold the 5V.
On the KingKong/Ldarc ESC/FC Combo i used first, the lowest i go by accident was 4.7V and nothing shuts down. Im sure that depend on the kind of FC used. I now ordered a HakRC F4 FC for testing.
As the Airbot Omnibus F4 v6 have some trouble and i cant get him to work, only with Betaflight all 4 Motors work fine.
All other FC i tested before, without Baro, seems fine with going down to 5V.
But i see no reason to go more down as 5V, as you damage the cells under 2.5V each.
The 78L12 LDO as example give constand 6V only and not 5V, the 5V must be from the FC itself.
From what i understand the LDO on the FC’s is only to make the Low Voltage Cutoff work.
Like in the Example KingKong/Ldarc wrote me:
78L12 LDO Dropout voltage about 1.7V
FD6288Q minimum power supply voltage is about 4.6V
so if you need ESC work reliably you need Vbat at lest 4.6V+1.7V = 6.3V
So without the 78L12 LDO you just need 4.6V for ESC to work.
I just lost my video reception about 800 meters away… Flipped RTL, and she landed in my yard :). First time I have had to rely on that… Super happy!
I don’t exactly know what’s wrong… Reception came back as it was landing. I think it’s a loose wire, but couldn’t get it to cut out on the ground… Though the video did get darker a few times, as I wiggled the video cable. Hate it when I can’t definitely find the problem, but I guess i’ll start by replacing the vtx cable.
Anyway, sorry to use this thread as a blog… But that was quite an experience… Hooray for ArduCopter!
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Hi, first test loiter.
1.9" props, 90 mm frame, 109 gr
And … Low battery
That’s a tiny copter!
Did you get auto-tune to complete?
What battery? 2" props might be too small for 18650’s, but I don’t know… I was surprised they work so well w/ 3" props.
Very very tiny !!
2 “props are very close to the cables, 1.9” give more space.
No way … also powered the FC from USB to the battery change, I have a reset of the FC and autotune restart.
The current battery is 450mA 2S lipo. As soon as possible I try with the 18650
Hi Alberto
Very nice tiny copter.
Can you give more info on components (Frame, FC, ESC, Motors, Props)?
Hi Andrea, thanks.
This is (very economic in this site) components list:
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@andyp1per I had the same problem with Autotune and now I have the log, could you please take a look at this post:
If you need i can upload a 3d Printed Frame for you, Size is 3 Inch and looksg similar to this you better can buy at Banggood: GEPRC 3mm
I printed this Frame, modified to 20x20 only and actual working on some leight weight ducts:
How to build the lightest Ardupilot microquadcopter 3-inch “2-stack” frame
Im using this Motors: Motor 1106-4300KV (2-4S) AMAXinno
Very quit and check the Thrust table:
190gr - 6 Amp on 2s
348gr - 12 Amp on 3s
if used with 3 Inch Props.
2 Inch is to small for 18650 Battery weight.
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Im happy you rescued your Copter!
Had such a Problem on my Phantom Clone with Mini Pix on Arducopter only one Time.
Dont know why, but i was unable to send any Commands to the Copter…like there is no connection to the RX…but RSSI was fine in OSD.
So i know the feeling wen you think it is lost, then RTH kicks in and you see your Baby flying Home
Thanks!
Andrea can you try with new 4.0 RC3?