wire lengths between ESC -motor / ESC - battery - RC Groups
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Nov 26, 2009, 09:06 AM
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wire lengths between ESC -motor / ESC - battery

I have a Phoenix 25 brushless ESC and a Himax HA2015 brushless motor on my Slow Stick. I fly off water only. When I tip the plane over, the motor, the ESC, the lipoly battery, and the connector between the battery and the ESC, always get submerged every time.

I m not worried about the motor, the battery, or the wire connectors, but I am worried about having to spend another $65 for a new ESC.

I want to move the ESC further aft about 10" where it would stay dry in a tip over. The Lipoly battery has to stay at the nose of the plane for correct balance. So then I would also have to lengthen the wires between the battery and the ESC also.

I wrote to both Maxx Products and Castle and this is their reply.

Lengthening the motor to ESC wires is less risky than the battery to ESC wires. If you notice any startup issues or other motor operation issues though you may need to remove the extensions. Spraying the controller with silicone conformal coating is recommended if flying off water. This is as waterproof as a speed controller can get. We've run controllers under water after spraying them with this. Of course you would keep the battery connections dry is key though as they are not sprayed. We offer this service if you'd like. The cost is $7.50. Please let me know if you have any other questions.

Joe Ford
Product Specialist
Castle Creations

Hi Jim,
Do it on the ESC side. The motor wires are braided magnetic wires and they are very difficult to solder.

Jarvis Yeh
Maxx Products

So after reading these two replies, I am still confused.

One is implying I will be having motor performance problems no matter what I do. The other gives me the go-ahead and do it.

I do know that I do not want to coat the ESC with anything other than what I have on it now. I wrapped it in saran wrap, extended the saran wrap out over the wires for about an inch on each end, and used twisty ties around the wires to secure it all together. This protects the ESC from the spray generated by landings and takeoffs, but of course, it does not waterproof it.

I tend to keep my planes for years and years and I just do not have any faith at all in any products that purport to be waterproof over long periods of time.

So what is all the mystery involved in lengthening wires between the ESC - motor - battery?

thanks, Dancer
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Nov 26, 2009, 10:42 AM
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EricJ320's Avatar
There is a thread on this about every other day or so it would seem. For the most part, people tell you to lengthen the ESC->Motor wires if you need to lengthen anything. If you do that, I'd say increase the gauge of the wires, and also twist the three wires so that you negate any RF interference they could create. The reason they recommend this over lengthening the battery->ESC wires is without adding extra capacitors you could damage the ESC over time from voltage spikes.

I often explain it like this and it seems to help people understand. The voltage is like water running through pipes on it's way to a faucet (the ESC), when the faucet is wide open you have water running through it at a normal pressure. If all the sudden you slam the faucet closed, the water that is already in the pipes moving has nowhere to go and is carrying momentum, builds up pressure, and sometimes causes the pipes to bang momentarily, and then pressure normalizes. The ESC works much in the same way, when you slam the throttle closed, the voltage in the wires that has already left the battery has nowhere to go since it will not be used. It builds up "pressure" against the ESC in the form of voltage spikes, sometimes very high. The ESC has capacitors on it that absorb those spikes, but if you add additional length, the voltage spikes can exceed what those capacitors are able to handle, and over time may fail, allowing the higher than rated voltage to enter the ESC and potentially do damage. To combat this, you need to add, according to Castle, 1 additional capacitor for each 4"-6" of battery wire you add.

Here's a picture of an ESC that I added these extra caps. It's pretty easy to do if you are at all competent with a soldering iron.

As for your waterproofing issue. I have a Seawind, and soak all my electrics in a product called CorrosionX. It works fantastic! I submerge the ESC in the stuff, and then turn it up on end and let the excess drain out. The ESC has been pretty much underwater, several times, and still runs great to this day. You want the stuff in the white and red bottle, with the pump spray. It's all over the waterplanes forum, it's good stuff!


Good luck,
Nov 26, 2009, 08:23 PM
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BEC's Avatar
Add 'em between the motor and the ESC. What Jarvis was saying was that it's hard to extend the wires that come directly out of the motor because those are the same coated wires that the motor windings are made from and are difficult to solder. No such problem adding an extension on the motor side of the ESC. The main thing is to match the three wires well so that the ESC can "read" the motor without any "distortion" caused by variations in the three leads between them.

I, too, use the water hammer analogy. I'll go a bit further. In a brushless controller, the battery side of the circuit is being turned on and off at the switching rate of the ESC at ALL times regardless of the throttle setting. Extending the wiring on that side makes the voltage spikes that the input capacitor is there to smooth out larger. If the leads get too long, then the voltage in those spikes goes beyond the rating of the cap and then BANG. It ain't pretty.

I don't fly enough off of water to have a good recommendation for making electronics water resistant. I do have a couple of CC controllers that have been treated with their conformal coating as Joe suggested in his note and I have seen Corrosion-X recommended many times.
Nov 27, 2009, 12:45 AM
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Mark Wood's Avatar
I use the Corrosion X on my water planes and it works very well.

Bernard, I think if I still lived up in the PNW all I'd be flying is float planes. Had full access to a cabin on Kitsap Lake for years and picked up flying not long before heading south. Needless to say, float flying is a bit far between in the Southland but I did manage to find a small club (5$/yr dues) that flies a local reservoir on Mondays.

Dancer, I suggest doing what you can to waterproof your electronics vs. lengthening wires to keep them out of the water. Believe me, we all dunk 'em once in a while and things WILL get wet.

Have fun!

Nov 27, 2009, 06:59 AM
Surface, Air & Water Rc Toys..
freechip's Avatar
I have a Art-tech EDF EF-2000 and the ESC is position all the way in the back right next to the EDF unit under the jet and the manufacturer has extended the ESC to BATT wires a good 6-10'' because the battery in up in the nose of the plane.

Try it and if you notice any difference in performance then stop or if you notice the wires getting hot then stop BUT I am sure you will be ok especially that were not talking about hundreds of AMPS but under 25A
Nov 27, 2009, 10:18 AM
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pilotpete2's Avatar
Hi Dancer,
Lots of good tips here
I use nothing but CC controllers, but I sure would consider using a T-Bird series instead of a Phoenix on a slow stick, less hobby bucks bucks at risk
Nov 27, 2009, 12:51 PM
Registered User
One interesting fact is water is not a good conductor of electricity. A scuba diver friend of mine demonstrated this to me by submerging a flashlight under water. It worked just like it did out of water. He said it worked like this even in salt water. It did however cause corrosion that ruined the flashlight.
I don't think you have as big a problem as you think.
Nov 27, 2009, 02:13 PM
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BEC's Avatar
There's a long way between a flashlight and a package of high frequency high power surface mount electronics.

My own experience is batting .500 on brushless controllers surviving a dunking and still being functional (with no precautions taken to protect them). I've not ever had a brushed controller still be non-functional after it had dried out after a dunking.
Nov 27, 2009, 02:45 PM
Registered User
Lot of good info here, thanks to you all.

I think I will keep the battery - ESC wires the same length as they are now (factory provided lengths) move the battery, ESC aft to keep them dry, and lengthen the wires between motor - ESC. Then I will move the wing and floats forward and see if I can balance the plane with the battery and ESC placed in their new locations, greatly aft.

If I cannot balance it, then I think I will put the battery on the nose again, lengthen the wires between the motor - ESC, lengthen the wires between the battery - ESC, and solder in the capacitors between the ESC - battery.

When I dunk a plane, it is under about an hour and 1/2 b4 I can recover it. I just cannot get it out of the water any sooner than that in my situation. That is why I am concerned about waterproofing a ESC when it is submerged for that long a time. I am not concerned about the conductivity of water (fresh in this case), but am concerned with the water going into places in the ESC where it should be dry all the time, and eventually ruining the ESC.

thanks, dancer

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