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jmb2232
08-29-2011, 12:40 PM
Hey guys! Just wondering what the consensus is about using a shorter BEC cable than the 12" ones supplied with the Jives. With the close proximity of the ESC and receiver on some of my birds, it sure seems like a waste (not to mention a mess) to use that much wire, especially when we're talking both master and slave cables. I was actually thinking about using the VBar 150mm/5.9" patch cables. Could there be a detrimental effect by using these? Thanks.
Mike B.

dl7uae
08-29-2011, 05:17 PM
The original lead is a bit thicker than 22 gauge (0.35mm).

The Vbar patch cable is a bit too thin I'm afraid, not to say flimsy.

mmarian
08-29-2011, 05:38 PM
It usually works fine with just master cable. Any additional cable will help to share the load. We are talking about 5 A, so it is not so critical what gauge is the slave cable, IMHO. I was using one made from a normal servo lead for a while without any issues.It did not have the ferrite ring, so I eventually bought the genuine Kontronik slave cable just to be safe.

jmb2232
08-29-2011, 10:37 PM
So if the wires are the same or lower gauge as the K BEC cable then I should be ok if the wires are shorter. There is no "magic" to the length of the K BEC cable then, correct?
Mike B.

mmarian
08-30-2011, 03:47 AM
So if the wires are the same or lower gauge as the K BEC cable then I should be ok if the wires are shorter. There is no "magic" to the length of the K BEC cable then, correct?
Mike B.

I do not know what you mean by "magic" but the length of the slave cable is not critical at all. As long as it can convey safely the amperage from your BEC. That is all that counts. Thicker wires have less resistance hence less heat generated but in this instance normal servo lead should be more than sufficient. We are not talking hundreds of watts in here.

Nko15
08-30-2011, 04:11 PM
Thicker wires have less resistance hence less heat generated but in this instance normal servo lead should be more than sufficient. We are not talking hundreds of watts in here.

I wouldnt pass the amperage of 4 fullsize digital servo thru one of those ''normal'' servo leads..

FYI, hundreds of watts could be at 400v, 5A, wich is 2000W, sounds like a lot, but at 30w, at 6v, its still 5A, and that is what counts.

22 gauge or more(lower number) is wished if you dont use a slave cable.

jmb2232
08-30-2011, 07:54 PM
I am planning on using a slave cable plus a buffer pack to boot. That is why I am trying to cut down on the mass of wiring if I can. I think what I will do, since I make servo leads all the time myself, is cut one of the K BEC cables in half, crimp on the appropriate connectors, and use the two halves as master and slave. That will cut my wire bundle in half from the ESC at least. ;)
Mike B.

mmarian
08-30-2011, 09:43 PM
I wouldnt pass the amperage of 4 fullsize digital servo thru one of those ''normal'' servo leads..

FYI, hundreds of watts could be at 400v, 5A, wich is 2000W, sounds like a lot, but at 30w, at 6v, its still 5A, and that is what counts.

22 gauge or more(lower number) is wished if you dont use a slave cable.

FYI, I am an electrical engineer and I would like to believe that most people with interest in this complicated hobby would know as much as the basic equation P = E x I or W = A x V, so there is no need to be smart in here. I said that we are not talking of hundreds of Watts in here, in reality of this particular situation the normal servo wire will simply do the job, as we are talking here of a peak of 27.5 W, that is 5 Amp at 5.5 Volt of Jive BEC default. That can be easily handled by a servo lead, especially if the length is going to be very short, I hope you would agree with that.

Nko15
08-31-2011, 07:04 AM
Than you should also know the peak can be way higher.. 4 servos can draw alot more than 5A when you pull the cyclic hard;)

prototype3a
08-31-2011, 01:50 PM
The Jive has two connectors for the BEC since it is capable of up to 15A and those r/c servo connectors are only rated for ~3A.

Try charging something at 3A using them and see how hot they get. I think it will surprise you.

jmb2232
08-31-2011, 02:11 PM
So is there an "official" amp rating for the wire and connectors of the K BEC cable? What gauge wire is used to make those cables?
Mike B.

prototype3a
08-31-2011, 02:17 PM
I don't know about the "cables" but those connectors are only rated for ~3A.

http://www.powerstream.com/Wire_Size.htm

That table seems to indicate 24awg minimum. I think the largest extensions I have seen are 22awg. I have the tools and parts so I just make my own cables :D

jmb2232
08-31-2011, 03:11 PM
After a little searching I found that the female (and male) gold plated terminals that I purchased from Hansen Hobbies are rated for 5A. I figure with these and 20-22 gauge wire, I should be good to go. :thumbup: Really what other options do we have?

http://www.hansenhobbies.com/products/connectors/servoconnectors/pt1in_ft/

Mike B.

prototype3a
08-31-2011, 03:18 PM
Sounds like a plan to me. I need to order some more connectors actually. My stash is starting to run low.

I say 3A because in practice, if you push 3A through them, they get pretty toasty pretty fast.

mmarian
08-31-2011, 06:37 PM
The Jive has two connectors for the BEC since it is capable of up to 15A and those r/c servo connectors are only rated for ~3A.

Try charging something at 3A using them and see how hot they get. I think it will surprise you.

Charging at 3 Amps means continuous flow of 3Amps over long period of time 20-40 minutes. That is a completely different situation to driving 4 digital servos which are not working at peak power all the time - that is for the duration of the average flight of 5-6 minutes. Anyway, do what ever makes you happy and be safe. The master Kontronik cable and the slave cable use the same servo connectors as ordinary servos and I know of nobody reporting a fire or overheating or melt down of those connectors during 6 minute flight:lol:.

prototype3a
08-31-2011, 06:40 PM
Congratulations for completely missing the point.

mmarian
08-31-2011, 08:26 PM
Congratulations for completely missing the point.

How did I miss the point exactly?? This discussion has taken an unpleasant detour and some people have obviously taken offence here. It was not intended. As I said before, do whatever makes you happy and be safe. To the end I am just reiterating what I said before and what I have been using for hundreds of flights on my heli without any issues. You can use the genuine Kontronik master or slave lead, you can shorten it to whatever length you wish or use any servo lead. Just make sure that the crimping is done well or use a solder for best possible contact to those tiny metal servo connectors and you'll be fine.
Good luck and happy flying :lol:

dl7uae
09-01-2011, 03:42 AM
Oh oh, no stress!:lol:

Inner resistance as low as mechanically possible (thick wire) and also crimping as good as possible. Btw the crimped connection and the contact itself (JR connectors) is the real dog, contact resistance. I managed it already to have 130C at such a connection by 10 amps continuously (in the lab).

(K says (in the manual), the toroid would generally be required, but actually he is not with 2.4GHz. And that, dear Ernie ;), although those 2.4GHz receivers are open as a barn door. The switching frequency harmonics of the BEC do not reach into this frequency range. - Apart from the encoding method of DSSS and FHSS are very resistant, even that wouldn't help with a stuffed receiver. - Thus, concerning the use of the toroid: Make it as how you are feeling better.)

Tom