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Old Apr 04, 2012, 07:05 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
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man all this rocket science ...i just want to plug the dang ESC in and go fly the instruction on the cap pack say install with in 3" of the esc ...but i need to move a bit further away ...like to 5" do you guru's think that will be ok ?
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Old Apr 04, 2012, 08:08 PM
Pursuit of Happiness
Ron101's Avatar
Brentwood, California
Joined Jul 2007
7,195 Posts
great info guys... I felt this was a good discussion

I had a really busy day and didn't get a chance to call Castel. They did tell me in the past adding one larger cap instead of a few smaller caps was just as good. But this was back in 08' with the CC 110 HV... I added one large cap to my A-4, it had a 20" extension and worked perfect for many flights


Quote:
man all this rocket science ...i just want to plug the dang ESC in and go fly the instruction on the cap pack say install with in 3" of the esc ...but i need to move a bit further away ...like to 5" do you guru's think that will be ok ?
Roger I'll have the same issue with my F-18....they will need to be 6" forward. The extension with be 30 inches long, so it will need caps... on my other CC 160 HV's I have no extensions just a short Y harness...but I'm still going to add a couple caps..
So I think if you have to move them 5" forward it's better than not having them at all... but I'm no guru
Did you see the scope test done in my old thread? you can see what a huge differance there was with the caps in place.... really smoothed out the spikes.
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Old Apr 04, 2012, 08:19 PM
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Arngeir Blakseth's Avatar
Molde, Norway
Joined Jan 2001
2,448 Posts
In my Falcon 120 I had to make up extension leads on the battery side, about 30cm long and I added 3 680uf caps to the esc end of the leads, but as the esc battery wires have not been touched there's probably close to 15cm of plugs and wire between the caps and the esc. The Turnigy Sentilon 100HV have worked perfectly so far.
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Old Apr 04, 2012, 10:43 PM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,413 Posts
Ron and Rodger, can't you tap into the batt feed within 3 inches of the esc and trace wire to the cap set location?
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Old Apr 04, 2012, 11:02 PM
Pursuit of Happiness
Ron101's Avatar
Brentwood, California
Joined Jul 2007
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Never tought of that!
that's a great idea... just not sure if there is any issue there. I will ask Castel when I call. But it sound like a great idea
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Old Apr 04, 2012, 11:49 PM
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racer1's Avatar
United States, AZ, Tucson
Joined Feb 2007
839 Posts
My CC ICE 2 160 has 470uf 50 volt caps. What caps are used on the new Castle Cap pack.

Does this mean I use 4 470 60 volt caps or just 2 of them.

So what caps do we use on the HV 160 or do we just copy the Castle Cap Pack.

Clay
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Old Apr 04, 2012, 11:53 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
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clay there is a pic of the cccap pack on pg 169 of my falcon thread.
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Old Apr 05, 2012, 12:34 AM
Registered User
Joined Feb 2010
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re the question about lumped capacitance(caps all in one location) vs distributed(spaced along the wire), the only reason I can think of is that Jeti seemed to have a transmission line concept in mind when answering you email. Knowing the rise/fall time product of the cap and inherent line resistance together with wave travel time you can adjusting the spacing to impact the way reflections occur on the wires. Not sure if that is what they were concerned about.
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Old Apr 05, 2012, 03:47 AM
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Eddie P's Avatar
United States, NV, Reno
Joined Mar 2000
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Quote:
Originally Posted by LJE4357 View Post
Form what I have read on this issue, most all of your are correct. There is one important issue your missing. Its the ESR (Equivlant Series Resistance) of the Cap. Cap's that are uses in swtching power supplys all use low ESR Cap's. Using any aluminum cap can cause a stability problem that I really don't want to go into here. If any of you design Switching Power Supplys, you will know what I'm talking about. One more issue ALL CAP's, especially electrolytic's, loose capitance with heat and age. This is an issue seen a lot on PC mother boards. Down the road, your not getting the total capitance you started out with. You can get around this by adding more cap's. The caps should be as close as possible to the ESC. Putting them in the middle can cause a stability problem with the inductance of the wire. I have seen this happen years ago with brushed motor. It can still happen with a brushless too.

My 2 cents worth
Larry E.
Knowing your background I'm pretty sure this is gonna be about as good info as we can get here!

I'll add that my dad is also an EE type and my discussions with him mirror the above. I asked him about adding caps in the middle of a long wire and he was under the impression that it would create more variables than take away but the Jeti guys have an interesting perspective and certainly have many thousand hours of high level thought on model applications.

For those looking for a cheap and easy place to buy caps, I buy mine from a variety of places.

http://www.thecapking.com/35zl220.html (this is for 4s, for example)
http://electronics.mcmelectronics.co...ow+esr&x=0&y=0 (random search, these caps are a little big but a refined search can be done)

Rubycon low ESR caps are among the best IMHO.

Type in "low ESR" into the search port and then find your mUf value. I also use about 1.5 times my planned voltage for my capacitor voltage. I don't typically add caps just to add them but I do if my battery wires are longer than 8" and in a few models, this is a fact of the size or application layout. When I do add caps I tend to add one cap of at least 220muf capacity per 4 inches of extra wire. As said above by others, one large cap is not as good as two or three paralleled caps for longer wires. I always buy radial capacitors, they are easy to solder up. Protect the wire with paint on insulation that you can get at an electronics store, don't leave any bare wire. Also, wear and tear on the caps is seen with swelling on the top of the cap - over time heat and rapid voltage charging will wear out tje caps but I bet they will last longer than most the airframes will! But if you saw one looking a little dodgy or see one go off they are easy enough to replace.

The other thing to consider. When we add caps, we are gonna get even more spark when hooking up. So make up your resister lead and plug that one in first to charge your caps slowly and not spark up your connectors. The batteries, connectors and caps will thank us
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Old Apr 05, 2012, 06:13 AM
awrightbrother's Avatar
Florida
Joined Nov 2007
2,489 Posts
Has anyone tried this method? If so, any feedback/discussion would be appreciated.

Locating the ESC close to the battery, and extending the motor drive leads. Any pros or cons by doing it this way?
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Old Apr 05, 2012, 08:26 AM
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United States, PA, Doylestown
Joined Sep 2010
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Would adding the caps back at the pack (in addition to at the ESC) help avoid the inductance concerns? Helping to kill any spikes at the source would seem to me to be an advantage in stabilizing the entire power stream.
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Old Apr 05, 2012, 08:27 AM
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United States, PA, Doylestown
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Quote:
Originally Posted by awrightbrother View Post
Has anyone tried this method? If so, any feedback/discussion would be appreciated.

Locating the ESC close to the battery, and extending the motor drive leads. Any pros or cons by doing it this way?
Think this might be a big issue for the ESC, and its' ability to discern back EMF so necessary to keep sync.
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Old Apr 05, 2012, 08:31 AM
Registered User
United States, TX, Grand Prairie
Joined Nov 2005
5,682 Posts
I've found with stiffing caps my packs come down cooler, they help with burst energy...

Why aren't the ESC makers just putting larger caps at the esc if voltage variance is such an issue.

The bigger the stiffing cap (resistance etc taking into consideration) the lower the chances of ripples.
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Old Apr 05, 2012, 08:31 AM
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United States, TX, Grand Prairie
Joined Nov 2005
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Quote:
Originally Posted by awrightbrother View Post
Has anyone tried this method? If so, any feedback/discussion would be appreciated.

Locating the ESC close to the battery, and extending the motor drive leads. Any pros or cons by doing it this way?
KV of the motor changes with longer ESC leads.

I think putting bigger stiffing caps at the ESC is the answer for longer leads here.
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Old Apr 05, 2012, 09:06 AM
Watt me worry?
Madmax1965's Avatar
Florida
Joined Mar 2006
3,857 Posts
I have been flying caps in my Hawk now for the past two + years and no problems. I use caps in anything 10s and above. I fly the Hawk on 10s but have used 12s. As I have stated before I almost burned my F-86 because of ripple current and since that time I have used caps in line. Everything runs cool in my planes now.

Concerning longer wiring...........I have posted this thread before(many times)and there is good info in it concerneing wiring and caps.
http://www.rcgroups.com/forums/showt...3#post10926525
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