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Old Apr 15, 2015, 11:07 AM
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More air time please!
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Longer FPV Flight time/Range (Fixwings) with Lithium Ion

Hi Guys/gals,

I have been tinkering with this idea on other threads, but wish to dedicate a thread to document it all in one place.

(please note its not my original idea, but i have decided to take it to the next step)

I have a FPV Ranger EX airframe, right now i get 80+ mins on a 4S 10AH 25C
Max amps is 27A and cruise at 5A-8A alot of tweaking and testing to get it to this.
FYI its a 775kv hyperion motor and 10X7 or 10X10 i use...not yet figured which is best for which situation.... ( climb or level flight etc..)

Improving a the equipment/ gear is one side of the game.... the other is the POWER source.... we have seen RC from Nicads.... to lithium... brushed to brushless.


We are all use LIPO for this High Discharge. But when it comes to FPV ( fix wings especially) we are aiming for Low amps....

thus the oportunity to use Lithium Ion.

Panasonic NCR18650B are Japanese made Cells, which have a capacity of 3400mah and weighs 45g each.

4S10P which is 34,000 mah and weigh only 1800g (Plus wires/tabs)


compare that of a lipo... at 4S 25C 10,000mah is approx 900g

but the NCR18650B whilst its ok to give 3C max... its best to run her at 1C or less. ( ref to Panasonic NCR18650B data sheet attached below)

i have ordered from China in 2 sizes.

A) 4S10P = 34,000mAh @ 1 C discharge its 34 A
B) 4S5P = 17,000mAh @ 1 C discharge its 17 A

For my fixwing, it draws 27A at take off WOT, and cruise between 5A - 15A
And i have flown with 20AH 4s 25C (1.9KG of lipo batts) and she flies wells.

So you can see that now with the same weight for a 20AH, i can now have a 34AH. thats a Big step forward.

but not all airframe can handle such heavy/size packs.

So we go for a smaller pack.

B) 4S5P = 17,000mAh @ 1 C discharge its 17 A

Taking off/ climbing to altitude will need much higher Amps then it can give at 1 C, remember we are trying to aim for max 1C discharge. Of cos lower that 1C is better ( ref to Panasonic NCR18650B data sheet attached below)

After testing I have come to conclusion there is no need to have 2 packs and switch. See my tests in this thread.

Then was mention wouldn't it be nice to switch battery in flight!, running Two battery Types. LIPO/ION and have a in flight switcher so that the 2 packs are independent from each other ( NOT connected at all), it has been suggested to connect them in parallel, but i believe separation is best, u can accurately monitor each packs during flight.

eg, your MAh count on current sensor. make note how much before you make the "Fuel tank switch over" etc..

I had an idea using a automotive relay, and after testing, to my amazement it work!! the ESC did not Cut or reboot... or loose Sync with motor....
In flight RC Battery Switcher (8 min 54 sec)


Solid state relay are heavier and bigger, hence we keep with mechanical relay.

I am getting made for me in China, a 80A relay with a 5V coil, ( should be approx 150mA draw when coil is energized to pull relay over) make sure u put a Diode across the coil, to stop HV flowing back when the coil magnetic field collapses

This will then be perfect to use with a DIY servo PCB, turned into a 5V switch on/off.

Back to the Lithium ION NCR18650B packs:

My pack is now on its way from China to me, here are some photos.

I have arranged to have a Chinese factory to Assemble these packs, Cells are imported from Japan, and will be assembled to my specs.
Each cell is tested for capacity, resistance then assembled into packs, and tested.

They did not give me the weight of the packs, i will have to weigh them when they arrive to see how much the wires and tabs added to the Original weight of 45g per cell. In the photo are two sizes, 4S10P and 4S5P

If anyone wants these packs made to their specs/configuration/size let me know.

Charge them with LIPO setting, (4.2V charged per cell)

Data sheet attached below.

Anyways, they are available if u want them.

My packs will arrive early/mid next week. will keep you all posted.

If i can fly 80+ mins ( flight summary gave me 130mah per KM) this is with a 10AH 4S 25C, and i have flown the same plane with 20AH ( did not exhaust the pack, only flew half way, and only saw slight decrease in performance) as the sun was setting in me....

what will a 34AH Ion pack of the same weight as the 20AH being discharged at .5C or even less! 3 hours ?.... i hate to put a figure... but i its gona be exciting to test!

Other test is running the 4S5P = 17,000mAh and have the switcher in place with a LIPO 4S 2200mAh 25C for the take off and climb out to ALT.

I feel this is a way to get more flight time with Fix wings.

Open for discussion and ideas to improve our FPV experience, lets see what we as a community can do
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Old Apr 15, 2015, 03:39 PM
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Old Apr 16, 2015, 12:12 AM
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Ok, working RC swtich yay!

In flight rc battery switcher part 2 (4 min 7 sec)


Please note if one can get a hold of a 5V activated "Automotive" RELAY which is impossible as automotive is always 12V

I have arranged for china to produce such relays (60A) with a 5v coil inisde instead of needing 12V as RC system, rc swtich is 5V.

waiting game for the Packs to arrive!....
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Old Apr 16, 2015, 12:15 AM
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there are 6 volt relays for cars, they date back to the 1950's
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Old Apr 16, 2015, 12:25 AM
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6volts will work also. If u get em its better choice than 12v ones. If u can't then get a 5v relay to run the 12v relay.

At 5v the 6v relay should still kick over.

Can u post a link of 6v 60a or bigger, that plp can buy if needed? Here in Australia cant seems to find.
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Old Apr 16, 2015, 12:28 AM
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FYI, the 12v coil current draw. Pls note the battery was 11.81 volts. (Not 12v)
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Here is a pic of the diode that MUST be soldered across the coil.
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Old Apr 16, 2015, 12:50 AM
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DIY Servo switcher

Sorry its all hot glued up.

basically a DIY servo switch is.

1. remove motor
2. center the pot and glue it it stuck
3. connect your (-) and (+) leads to the original terminals.


With a multimeter and a servo tester, on one position on the tester, u will find it will give u 5V ( positive) and on the other position it will give you negative (-5v)

For led its cool, as Led are diodes, reverse polarity does not harm them, hence led TURNS OFF.... and on... when polarity is switched again.

For relays, data sheet recommend not to reverse the polarity, but from my testing i have reversed them... and they still work, ( not burnt out).

So to stop the senario of reverese polarity when we flick the switch... from 5v to -5v

pmackenzie (Pat Mackenzie) on another thread suggestion a simple solution! too simple that i didn't think of it!

was to have the (-) wire that gets connected to the (-) relay (coil) pin soldered directly onto the Ground wire ( black/brown) of the servo lead. which will never reverse on ya. and the (+) wire to any one of the terminal where the original servo motor was.

WElla! solved!

oh.. ... sorry for the extra hi res pic. pls zoom in!
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Old Apr 16, 2015, 12:52 AM
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Originally Posted by chanyote66 View Post
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Just realized you the bloke with the mobius cables when they first came out! i remembered seeing your thread years ago! haha! small world in deed.
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Old Apr 16, 2015, 03:04 AM
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I have seen bi-stable latching relays that don't require constant current, only to switch
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Old Apr 16, 2015, 03:15 AM
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Old Apr 16, 2015, 03:18 AM
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Quote:
Originally Posted by MikeTheCrash View Post
I have seen bi-stable latching relays that don't require constant current, only to switch
I know of the latching ones, generally they are Bigger. and more complicated, more components and systems...

So far it seems readily available are automotive relays are most stable/simple and best size/weight for the work that needs to be done.
@ 28x28x25mm not bad at all.

But always looking out for better options...

Things to keep in mind.

1. size and weight
2. High current side 60A or so...
3. simplicity... redundancy.. if relay fails... whats the scenario then?
4. We are only POWERING the Relay for like 10% - 30% of the flight.... LIPO selected on take off, climbing...etc...
The rest of the flight we will be running on ION, NON POWERED relay.

keep them ideas pumping thru!
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Old Apr 16, 2015, 03:40 AM
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Quote:
Originally Posted by airoscar View Post
Have you tested it with ESC and Rx connected? One thing to watch out for with the relay: if you are connecting both batteries to the relay, the time between the relay switch disconnects first position to the when it connects the second position may be enough to cause the ESC or receiver to reset, especially with a mechanical relay.

Dont quite follow, the RX is always on, never a micro second there it gets disconnected. the only thing is the ESC. which seems fine. from the tests.
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Old Apr 16, 2015, 07:13 AM
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Mobius Cables... I got em'
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Quote:
Originally Posted by Hobbyzone.Au View Post
Just realized you the bloke with the mobius cables when they first came out! i remembered seeing your thread years ago! haha! small world in deed.
yup still making them too. I now have a 7g cable for AV out and charging that supports 2s-6s

Im working on a 9g version with OSD that includes voltage amperage and amp draw and flight time. Its a slow process though

Chris
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Old Apr 16, 2015, 07:24 AM
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Can u confirm Möbius current draw when charging and current draw when batt is full. . . be good to know how much I load up my ubec 5v.
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Old Apr 16, 2015, 07:58 AM
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Mobius Cables... I got em'
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Quote:
Originally Posted by Hobbyzone.Au View Post
Can u confirm Möbius current draw when charging and current draw when batt is full. . . be good to know how much I load up my ubec 5v.
strangely it depends on the generation. I have two mobius that draw different amounts.

The most iv seen them pull is 490mA from a dead battery while recording. and with a full battery/cap iv seen them draw from 300-400mA. My cables use a 3A regulator which is overkill but well worth it because it will never heat up.

Chris
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