F550 Radio Setup

C

Charlie.

Member
I ended up buying 1 4500mah 3S 50-100C Best DNA LiPo from Hong Kong on eBay for £20.

I also bought a parallel XT60 cable to try and use my current 25C 5000mah packs in parallel and see if that makes a difference. I have been told by blade-hobbies on eBay that as my batteries are only 25C, I can run 2 of them through a 14AWG parallel cable without any problem or damage. Is this true?
 

gtranquilla

gtranquilla

RadioActive
Increased conductor resistance reduces your system efficiency, i.e., will only decrease your total flight time and/or possibly slightly reduce the peak voltage that might otherwise reach your motors due to voltage division. I don't see a risk of damage at all.
The two upper legs of your parallel "Y" connector should be the same wire size as the conductors coming from each battery. B
ut since the bottom of your "Y" connector has to handle the currents from both batteries, it is preferable that it be a larger conductor, i.e., #12 or #10 awg.
Typically a Y" parallel connector standardizes on one common cable size. I typically make my own.....

The answer to such a question is relative, not a definitive yes or no, which leaves lots of latitude for a typical salesman's answer.....i.e., Is he working for the customer or the boss?
Personally I prefer to work through the math to reach my own conclusions.
The 25C battery rating is just one factor in determining the appropriate conductor size(s). The other is your electrical load, i.e., motors.
In any case this is not math but simple arithmetic (addition) unless you need to get in to ohms law which would require a bit of multiplication and/or division.
E = I*R where E = volts, I = current (amps or milliamps) R = resistance in ohms. If you know the combined resistance of all your motors under full load you can calculate your maximum current travelling thru the bottom part of your "Y" parallel connector.






Charlie. said:
I ended up buying 1 4500mah 3S 50-100C Best DNA LiPo from Hong Kong on eBay for £20.

I also bought a parallel XT60 cable to try and use my current 25C 5000mah packs in parallel and see if that makes a difference. I have been told by blade-hobbies on eBay that as my batteries are only 25C, I can run 2 of them through a 14AWG parallel cable without any problem or damage. Is this true?
Click to expand...
 

B

b0nafide

Member
Charlie. said:
3: How would I actually go about binding my receiver to my transmitter? Does it need a bind plug or is that only for spektrum radios? Do I just need to press the F/S buttons on both the receiver and transmitter module? Does the receiver get power from the Naza?
Click to expand...

Hey Charlie,

Obviously you got this answered. Care to explain?
 

C

Charlie.

Member
I am using the Frsky DJT module with the D8R-ii plus receiver.

Binding was really simple with my module/ receiver. All I had to do was plug the module into the 9XR (with the antenna on of course) and then turn the 9XR on whilst holding down the little white "F/S" button on the module, and then the module is ready to bind with the receiver.

For the receiver, hold down the little "F/S" button on the receiver and power up the F550 (the receiver is powered by the naza and I had all my receiver outputs connected to my naza before I did the binding). Then the light on the receiver should stay on indicating that it has been bound to the transmitter.

Then turn the F550 off, then the transmitter off. Then turn the transmitter back on and then the F550 back on and you should be bound and ready to configure the radio!

As the 9XR let's you change all the channels around it doesn't really matter which outputs from the receiver you plug into the naza's inputs as you can change them all on the "Mixing" page on the 9XR.

I am having a problem with my F550 because the red light on the naza flashes after a very short time, so I think it is something to do with the batteries (mine are only 25C).

Hope this helps! Good luck with your own build!
 

CrashMaster

CrashMaster

Member
Charlie,
I have no doubt the batteries are causing the early red light flashing. If you are adding load to the machine i.e. fast assent then the lights will come on very early if they are marginally within load tolerance when fully charged. I use 2 x 35C and get exactly this at about 6 mins flight but have another 4 - 5 mins before the lights flash continually in a steady hover.
Try placing your machine 20ft up in GPS hold and time it until it lands it's self. Note the times the red begin to flash and when it begins to descend on it's own.

Bearing in mind that the highest loads are only pulled when ascending fast or the motor draw is increased to maintain stability in windy conditions. If you have stock motors and ESCs you can be pulling upward of 180amp (that is 180,000mah) if fully loaded and ascending full throttle. The fact your Naza is flashing could be a good thing as this is warning you that you are pulling too much power and you back off. This will extend your flight time as your 20C will last longer in the air than a 30C. However, there is also a direct relation to the longevity of cells when used at maximum or near maximum discharge rate constantly. The usable cycle times of a 20C is fare less than a 30C of a 70C this is due to the internal damage done by maximising internal stress on the cells by pulling maximum power.

I found this thread in the RC Group Forum which may put more light on your and my dilemma when deciding on what cells to use and where.
You may also want to look at http://www.rchelicopterfun.com/rc-lipo-batteries.html and http://batteryuniversity.com/ .
 
Last edited by a moderator:

C

Charlie.

Member
Thanks CrashMaster!

Do you think that if I ran my 2 25C lipos in parallel the problem would go away? Doing so would bring my AUW to about 2.35kg
 

CrashMaster

CrashMaster

Member
The F550 is more than capable of taking 2 25Cs. The potential discharge rate would be doubled while the voltage remains above 11.1 for longer. The other advantage is that despite the additional weight the flight time will be extended by about 40% over 1 25C. A simple Y cable can be used but do ensure you use at least 10 gauge cable. Also use the correct props for the 3c - 10" and 4c - 8". DJI know a lot more than you or I about the machines and wouldn't offer this simple instruction without good reason.
I appreciate that this is only one of your problems but resolve this and it is one less thing to worry about and confuse the other issues.
 

gtranquilla

gtranquilla

RadioActive
Crashmaster.... thanks for the excellent information on the batteries and why the intermittent red flashing occurs. As for the DJI F550 prop recommendations, I have been consistently using the efficient 9 x 5 Graupner's with 4C batteries with great success..... so this might be one exception to DJI's recommendations that remains safe to consider. It's all about amps and esc limits I believe.

CrashMaster said:
Charlie,
I have no doubt the batteries are causing the early red light flashing. If you are adding load to the machine i.e. fast assent then the lights will come on very early if they are marginally within load tolerance when fully charged. I use 2 x 35C and get exactly this at about 6 mins flight but have another 4 - 5 mins before the lights flash continually in a steady hover.
Try placing your machine 20ft up in GPS hold and time it until it lands it's self. Note the times the red begin to flash and when it begins to descend on it's own.

Bearing in mind that the highest loads are only pulled when ascending fast or the motor draw is increased to maintain stability in windy conditions. If you have stock motors and ESCs you can be pulling upward of 180amp (that is 180,000mah) if fully loaded and ascending full throttle. The fact your Naza is flashing could be a good thing as this is warning you that you are pulling too much power and you back off. This will extend your flight time as your 20C will last longer in the air than a 30C. However, there is also a direct relation to the longevity of cells when used at maximum or near maximum discharge rate constantly. The usable cycle times of a 20C is fare less than a 30C of a 70C this is due to the internal damage done by maximising internal stress on the cells by pulling maximum power.

I found this thread in the RC Group Forum which may put more light on your and my dilemma when deciding on what cells to use and where.
You may also want to look at http://www.rchelicopterfun.com/rc-lipo-batteries.html and http://batteryuniversity.com/ .
Click to expand...
 

C

Charlie.

Member
Thanks again CrashMaster,

I think the only problem I am having at the moment is the flashing red light. The multi copter itself flew great when I used it. My batteries have XT60 connections, and making a parallel adapter with 10AWG wire is almost impossible I think. Some sellers do sell 12AWG ones though, but the norm is 14AWG. Do you have any recommendations for a parallel XT60 harness?
 

CrashMaster

CrashMaster

Member
Charlie. said:
Some sellers do sell 12AWG ones though, but the norm is 14AWG. Do you have any recommendations for a parallel XT60 harness?
Click to expand...
Short of making your own your local hobby shop will probably stock a simple Y cable. If not people like HobbyKing will have them in stock.

gtranquilla said:
I have been consistently using the efficient 9 x 5 Graupner's with 4C batteries with great success.
Click to expand...

It may be that the load is OK at 9" but the 4S does spins up the motors faster so this could putting an awful lot of Amps through your ESC if your props are too big. The side effect is excessive heat. check your ESC at the end of a flight and see if they are hot. Mine are just nice and warm. The motors are only slightly warm. Meaning I am not putting the Motors or ESC under too much stress. By the way I use Graupner 10" and 3S x 2 3300mAah.

By the way I am no expert just been in the game a long time and tried the turbocharged to find it breaks so normally keep well within safe limits. Cautions but long lasting....
 

C

Charlie.

Member
That HobbyKing cable you linked CrashMaster is only 14AWG judging by the comments and you said earlier that I should use at least 10AWG cable? I did buy one of those parallel connectors from HobbyKing 1 week ago when they were in stock so they should be with me soon. Do you think it would be safe to use?

Also I am using 10" 'New' DJI .38 props with my 3S batteries so I should be fine hopefully :)
 

CrashMaster

CrashMaster

Member
Charlie,
You are right - I also found these at Hobby King:-
http://www.hobbyking.com/hobbyking/...ry_Harness_10AWG_for_2_Packs_in_Parallel.html
http://www.hobbyking.com/hobbyking/store/__23132__XT60_Harness_for_2_Packs_in_Parallel_1pc_.html

The thing is to make sure it is parallel and not series. Parallel will keep voltage. Series will double your voltage and kill your controller.

The lower the AWG the thicker the wire... 1AWG is 7mm wide and 10AWG is 2.5mm. You are better to have 10 than 12 which is only 1.6mm due to the potential loads a multi can pull. An F450 will be fine with a 12AWG but the F550 I use 10AWG. This allows upgrade later to more load, if I decide to use the heavy lift extensions.
 


C

Charlie.

Member
Thanks again,

in the second one you mentioned are the XT60 connectors soldered directly to each other? Would that one be equivalent to 10AWG wires? I have already soldered XT60 connectors onto my batteries so I don't think I want to remove them and add XT90 connectors, although that would probably have been better to start with!
 

B

b0nafide

Member
CrashMaster said:
The thing is to make sure it is parallel and not series. Parallel will keep voltage. Series will double your voltage and kill your controller.
Click to expand...

But if I were to charge two 3S packs side by side (at the same time) through a single charging lead, I would hook them up to in series to charge?
 

C

Charlie.

Member
Hi again,

A package from HobbyKing arrived today which included a XT60 parallel cable. The problem is that the wire is only 16AWG :(

If I were to use this with my two 5000mah 3S 25C batteries would it damage the batteries or not operate well with my DJI F550?
 

gtranquilla

gtranquilla

RadioActive
Risky!!
In addition to reduced flight time, undersized conductor can get hot which can drive up it's resistance leading to a thermal runaway condition, insulation breakdown and a dead short etc. etc. And that is not a good thing during a flight. Except for the undersized wire, you can still use the remaining parts. Have you considered building your own parallel cable or getting someone to help with that?
 



gtranquilla

gtranquilla

RadioActive
There are often tradeoffs but that item would be a reasonable compromise for your existing batteries. You might want to buy or build a larger gage one if you ever opt for larger motors and/or battery mah capacities however.

Charlie. said:
I am thinking about buying this

http://www.ebay.co.uk/itm/Heavy-Duty-Turnigy-XT-60-XT60-Parallel-Battery-Connector-12awg-Wire-/230838159612?_trksid=p5197.m1992&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D14%26meid%3D5962046393424982040%26pid%3D100015%26prg%3D1006%26rk%3D1%26sd%3D230838159612%26

This one has 12AWG and my batteries use 10AWG, but the connector on my hexacopter only uses 12AWG anyway.

Would this do the job?

Thanks
Click to expand...
 

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