Cap banks - the pre-emptive answer

[drwayne]

Hey, The boats I wire go BOTH Over and Under----that is only when something goes wrong!
Now seriously I have a question: on 10 or 8 ga. wires that come with some ESC, if I were to solder a cap bank onto the wires near the ESC, the stripped insulation spot need to be properly pre-tinned. It takes quite a bit of heat to achieve that, my soldering technique is average to slightly above average, how much risk do I have before damaging any soldering joints up stream and also electronic components. I hold the wire with cold/wet towel---no dripping water to wet the ESC, of course.
I hope my question does not lower the value of this thread. I feel as if my question is like the ugliest house on the block, lol....

I use 120W(240VAC) copper blade solder iron with large tip when 'gluing' large cables ..the heat held within the large tip prevents the need for extended heating to perform the task ... I assume your cap wires are entwined within esc cable.. put some solder to solder tip before you touch the cable.. it will penetrate quickly and then some additional maybe needed to fill the strands ..a few moments is quite fine. Pause between each solder point to allow the cabe to cool..residual latent heat will progress quickly through the cable.
Wet cloth ?..nope ..use a broad grip pliers to hold the wire ..the quick heat and solder technique above is fine.
A wet cloth would 'flash' heat the moisture closest the cable and offer no true heat restraint ..

[tlandauer]

Thank you very much!

[kevinpratt823]

OK, I'm not sure how you figure I have changed wording, outcome, and fact...? In my first post I speculated that the heat generated would be the same, in my last I basically repeated it. A couple posts between I actually gave a link to some answers to the exact same scenario in a purely resistive circuit, which has doesn't have all the extra properties of complex electronics that you are likely used to.
If you missed it, the question in the link was:
"Will 4A at 110v AC lead to a greater temperature rise than 4A at 24v DC in the same wire?"

The answers......
"No, it won't. The heating is caused by the I²R loss of the wire and not the voltage drop. The 4A AC is an RMS (Root Mean Square) value which is the energy equivalent of 4A DC."

"Also, thermal heating is a function of current only, not voltage"

"The temperature rise along the length of a cable depends only on the current it is carrying, the cross-sectional area and the material it is made of."

Or the one that backs up what I said about getting a voltage drop, but not more heat......

"However, with low voltages, it is generally more important to minimize voltage drop: if the cable carrying 4 amps has a resistance of 1 ohm per conductor, then it will be dropping 4V along the length of each conductor. So your 24V DC appliance will only be getting 16 volts! (4 volts are lost in the positive supply and another 4 volts in the negative return.) You might well want to use a thicker cable which will have less voltage drop. But a 110V AC appliance would be getting 102 volts at the far end of the same cable, which is a bit nearer the mark. Either way, the cable will be dissipating 32 watts of heat along its length." (And as I pointed out, our wire was already rated to dissipate the heat produced, the resistance of a 6' run at a safe initial operating temperature is hardly enough to trigger a cycle of thermal runaway)

I'm not sure what you're basing your "heating profile" on, but the above is some of the information that supports what I have spoken of all along. And even if you have some kind of calculated discrepancy, it's not enough to melt the wires.

All of these are perfectly in line with what I have said from the start, and nowhere along the way did I change that, not sure what you are talking about. In a purely resistive circuit, the RMS readings for AC current and voltage are basically interchangeable. In your electronics circuits with capacitors, induced voltages, pulsing, etc., those equations are an evolution of AC theory, just a little more involved. So yes, AC theory is relevant, much of it is actually interchangeable.

You are the one that said you weren't talking about your toaster, now you are hooking it up to 480vac to prove what? The numbers in your irrelevant scenario don't even make sense! When you quadruple the voltage to a resistance you quadruple the current(it wouldn't stay at 22.7) the wires will fail,... really? Isn't that kind of what I was getting at when I said you have to go way out of the ratings for it to fail? I just referenced 480v in terms of it producing the same heat in the wire at the same given amperage......Let me spell it out again though, if you hook the toaster up to 480v, it will draw 99 amps(for a very brief second), that is 47.5kw(not 11kw). Kind of like if you hook it up to 25vdc it will only draw 5.15 amps, we've already covered this, the toaster is irrelevant, your scenario doesn't even make sense, we are talking about a wire, with a given fixed amperage, at 2 different voltages.

This is copied/pasted from your example......"AWG#12 at 110VAC will carry 2400W... for 33' !!!!!!!!"
Did I miss the part where this becomes DC, bravo? Maybe you had a typo.

BTW, I think you misunderstood Cooper, I'm pretty sure he was implying that sometimes the copper tube, when sized correctly, would work better than ANY stranded wire, as in even one with more surface area."cardboard tube clad in copper would carry a better signal than ANY multi strand wire at a very specific diameter and frequency." "more skin= more transfer is just not the case".
Read his words again.

And I did not claim wiring boats as my father's profession, just that he does it. He has retired from the phone company, where he managed the projects and maintenance of the building systems and infrastructure for several large buildings in Boston. But his heart has always been in his and my brother's commercial tuna boats, just so happens he has the background to do a lot of different things(like basically build and wire the boats), but he does still renew his master electrician's license.

BTW, if you've never seen a 900 lb. bluefin Tuna be stopped dead in it's tracks by electricity coursing through the first 150' steele cable line of a harpoon dart, through another 70' of saltwater, back to a ground plate under the boat, it is a sight to behold for any electron aficionado.

As entertaining as this healthy debate has been, you have had a few days now, and still haven't given any solid evidence of your original claim. In fact, judging by the way you switched from skin effect, to thermal runaway, to grasping at straws about heating profile, to bags of horse $hit and irrelevant scenarios like quadrupling voltage and current, I'm still wondering what you based the original statement on to begin with. Feel free to keep picking my comments apart with technicalities, but you have noted nothing substantial enough IMO, to lead me(or probably anybody else reading) to believe the wire would melt, despite everything my own knowledge, experience, and research has told me, so I guess I can just walk away from this. At the end of the day, the #12's to the baitwell in the boat don't melt, my trucks headlights don't melt, the cheap 10 amp car battery charger doesn't melt...........But if I ever stumble across a good 1.1 ohm/567.5watt resistive load, I'll hook it up to a set of 6s2p packs with a 6' extension cord and send you the video, complete with a clock and IR readings, so we know for sure.
Until then, I guess I'll just "agree to disagree".

Feel free to delete all of it, it's your thread. I do feel, though not all relevant to capacitors, there actually is some educational stuff in here between the 2 of us, if you get through our tiresome banter.
Cheers

[drwayne]

I run this thread to offer guidance through "DC Power 1.01(a)" ..not for debates on semantics or country specific nomenclature.... or topics or deviations which detract from my intent to support this hobby through applicable DC theory.

persons who fail to observe that purpose . . . . straight to the naughty corner it'll be from now on.

I had no urge to 'ignore list' anyone from here.. despite some worthy persons suggesting a need ... after 2 pages of repetitive banter I checked one user's profile and found that degrading opinionated haranguing posts are his forte ( excellence )...
bye bye.......

[jj2003]

Would it benefit putting an external cap bank (Etti E041 63V 5000u) on a MGM 40063-3 X2 ESC? It comes already with (4) 63v 1000u capaciter's. Power will be (2) 7s 5000mah 65c in series for 14s with 2 more in parallel for 14s 10,000mah 65c. MGM controllers (2) will be connected to Lehner 3080/5 LK's. Hull is 92" Radtek with possibly 1865/3 blade props'....Any help appreciated :)

IMG_20140831_105456.jpgIMG_20140831_105552.jpg

[drwayne]

Hello.
Those esc have loggers.
Take your your toy for a run and check for voltage drops under load.
Share that info !
Regs W

[drwayne]

jj2003
2x7s in series.. doubled = 14s1000mAh.. assume per esc ?
7s ? odd size.
lmk.

[jj2003]

Exactly. It is odd size. I would like to run 12s and use long pack's but I don't think it's enough for a Lehner 3080/5 LK. 1050kv in D and 607kv in Y.

[drwayne]

Is this for SAW, Oval, or for the shi.tzengiggles thrill ? ..

[jj2003]

Is this for SAW, Oval, or for the shi.tzengiggles thrill ? ..

The shi.tzengiggles thrill !

I'll have mucho dinero, big bucks, Grey Nurses, or depending on how new the money is, Gorilla's
invested and I just don't want to blow anything trying to go fast.
I dont race professionally or amatuer but I would like to do a little of both roun-d-round and a few passes at full bore on an outing,
or focus on getting that single high speed pass at one outing and then try some circles another.
It's a hobby and I expect failure at some point, but I don't want to cut myself short if I could have prevented it by adding caps
P.S.
Thanks for your thoughts on this, I appreciate your input

[drwayne]

92" is a damn big tug.
Will this be RC, or is there a chair fitted for manual steering ?
I ask to gain some idea the total weight on water ... ???

Driving technique will identify what capacitor buffer suits you best.
Are you a gentle squeeze and go throttler ... or one the punch and go-hard type ?
Surge demands are what customizes these arrays.

Yes, a cap array can be produced to suit both ends the go-hard or gentle approach, but it will be just adequate for either.
A dedicated purpose built job is better for that end of day grin.
Two interchangeable arrays per esc ... costing is minor compared the 'Presidents' dedicated to this build...

Sooo.. what total mass for this toy... and how violent is your finger ?

[keithbradley]

92" is a damn big tug.
Will this be RC, or is there a chair fitted for manual steering ?
I ask to gain some idea the total weight on water ... ???

I think these come in around 65lbs. Wayne...obviously depending on how many cells are in the hull.

[drwayne]

65lb ?.. wow
The 92" cat is just 19cm(~8") shorter than my jetboat !

minime.JPG

LOL

That's why I asked about the chair

[danzigneg]

I've done making extra cap bank for my esc. Wish to get some comment regarding my build. Not yet tested.
By the way, here are some detail:

Cap bank:
Chemi-con 35v 1000uF KZH
6 pieces
Parallel connection

Boat setup:
Silver Fox 36" catamaran
Twin setup
Turnigy 180a v2 esc
TP 4050 2050kv
Turnigy Nano-Tech 3850mAh 65c

Will it it work?
IMG_20140922_081700.jpgIMG_20140922_081739.jpg

[drwayne]

I've done making extra cap bank for my esc. Wish to get some comment regarding my build. Not yet tested.
By the way, here are some detail:

Cap bank:
Chemi-con 35v 1000uF KZH
6 pieces
Parallel connection

Boat setup:
Silver Fox 36" catamaran
Twin setup
Turnigy 180a v2 esc
TP 4050 2050kv
Turnigy Nano-Tech 3850mAh 65c

Will it it work?
[ATTACH=CONFIG]120912[/ATTACH][ATTACH=CONFIG]120913[/ATTACH]

very good.
What voltage ?... cell count ? 4S, 6S ?

the factory small external cap bank is not needed.