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Joined Aug 2009
888 Posts
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I don't think that the KV of the motor changes with longer motor leads to the esc. What determines a motors KV are the amount of turns the wire takes around the stator and the strength of the magnets (if magnets get overheated and lower their magnetic strength, the KV increases).
The only issues I'm aware of is possible radio interference from emf which is easily solved by twisting the leads to null it out. If the back emf isn't functioning correctly, you should know immediately as he motor won't operate correctly. Terry |
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United States, TX, Grand Prairie
Joined Nov 2005
4,988 Posts
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All good stuff guys...
I'm ordering caps this morning and will use the 330 UF on my stuff with shorter y harnesses..... where I don't need so many caps But on something like my F-18 which needs a 30 inch lead I'll go to the bigger 680 uf's and run five instead of needing 10 I know the extending the motor wires or power lead debate has gone of for sometime... I have used both with good results as I know many others have to with the use of added caps As for the ESC in the tailcone debate.... I have also done it both ways with good results. I think it's good to be flexable and do what is best for a given project Take my twin F-18... there is no good place to mount the ESC forward of the fan and get any cooling to them... it will carry two sets of warm 12s 7800 mah packs adding heat to the inside of the fuse. The tailcone on the motors is the best place for the ESC in this case. In my Hawk and Spark... I found good spots forward of the fan to get cooling. So you just have to go with what works.... We know that BVM and Tam have both had great success with the ESC in the tailcone.....many have had thermal issues with no cooling (but that is for another thread ) I've had good luck with either setup as long as you think it out and plan well... naca ducts, added fans, caps, resistors... ect. can all help
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Joined Feb 2010
223 Posts
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"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 "
I agree with that. First order approximation using a lumped capacitance approach like Castle has done should get you the majority of the benefit in smoothing out the voltage signature. |
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United States, TX, Grand Prairie
Joined Nov 2005
4,988 Posts
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K, ....sigh
Why doesn't caste simply add bigger caps to the ESC to smooth out current flow? Caps are relative inexpensive and light...and easy to attach.... Cause it's not the caps, it's the FETs are out of tolerance from factory...SUPPO esc's went through a bout of bad FETs on their esc's and they were gimped because of it. It only takes one to fail or heat up to the point were its properties change and make others fail... Yaws take? TIA |
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it may take longer Roger... it said 6 weeks when I sent mine in early in the recal and it took over 2 months and kept all my best planes grounded. Oh I missed you question on smaller ESC I won't add caps to my 3s, 4s, 6s, stuff.... it's been working fine. Even my Spark is on 11s with an old CC110hv ...it's got so many flights I'm not worried Just adding to my new CC 160 HV 2 12s setups |
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Here's a good question, would caps help on 3s, 4s, 5s when using partial throttle mostly during a flight? After following the links posted here it seems like a good idea regardless of lead length. I half understood the switching more at lower throttle and the inductance thing.
Thanks! |
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Joined Feb 2010
223 Posts
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Its a good question. Why is Castle selling a cap pack anyways. Because of under-design? I wouldnt think so since the recent HV2 gave them the opportunity to rev the design entirely if they didnt feel it was sufficient. It could be simply due to form factor alone or form factor together with cost to go with something that works for most end users(staying positive here I know). And for a select few, which may have slightly different requirements they are able to sell them an additional product that must have some decent margin for them. Does the Castle Link data log software have a popup that says "We noticed your data log and hey you need the cap pack - click here to buy now". Now that would be definitive.
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db
Castle sells cap packs because guys want to/need to lengthen their battery wires. if you look at your esc, any esc you will see at least two caps on the end. those are for a 12in wire length, 6in for the esc side and 6in for the battery side. this is how all esc's are designed. so it doesn't matter if its a castle esc or any other esc if you lengthen your battery wires then you should add caps for the additional amount of wire. their is no design flaw or conspiracy
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Exactly! The caps included should be sufficient for most planes but when we start making our wires super long that's the problem. Seems like some of you are missing the point, before you go running off and buying caps, do the math I shared earlier in the thread and see if you even need them. NOT doing the testing and reviewing the data correctly is why alot of esc's end up as charcoal. And if temps are not correct, well caps are not going to help that. Seems like alot of people never even look at the data, if you are going HV that should be mandatory! |
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United States, TX, Grand Prairie
Joined Nov 2005
4,988 Posts
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and when I say FETs its the Fets...not a regulator or some resister or the MCU got spiked...the FET cracked almost in half They replaced the ESCs promptly Thank goodness they were all on the ground, one guy who's been flying with them for years popped them on hook up of 6s pack 5 months ago. It's not voltage run time variances, to fix that it's cheap and light and easy... |
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