Common caps for two escs?

[CraigP]

Oh, I see what you did there. Clever.

I haven't done anything, but the questions didn't get answered. I think what is happening is that the unplugged ESC is getting power from the Y Cable and charges the ESC's caps. Then when he hits the throttle, that cap charge spins the unplugged motor for a short period of time. The Y Cable can't supply the current to keep it going, so the BEC is probably going into current limiting, which cuts off the receiver, then the process repeats. I don't think it is mutual magnetic field coupling because the motor I think (it was a question I asked) is turning in the opposite direction. Plus there is a lot of metal mass on the out runner and it does a good job of soaking up most of the magnetic field. Any field that leaked that much would make a pretty inefficient motor.

This is a good video showing that current can flow through wires that we wouldn't think of as high current carriers and actually should not be. I love out runners!

[Jesse J]

That’s cool! Just to re-cap:
1) ESC 1 is plugged into a battery, while ESC 2 is not.
Question: Do either ESC’s have a BEC?
2) Both ESC’s are plugged into a Y Cable
3) The Reciever is powered up, assuming this true since the motors are responding to a speed input.

Question: Hard to see from vid, but does the unplugged motor rotate in the proper direction, i.e. opposite of the other motor.

I think I know what’s happening, but need verification and question answered. Bottom line, you may be demonstrating the exact nature of the problem I was describing. Meaning wire connections can have unattended consequences! Thanks for sharing

Yes to all questions.
Your explanation seems very plausible. I agree that it's probably not the magnetic field as I proposed in the vid.

[golfito]

That same try to describe on my boat with both T180.
A single battery. External Bec. "Y" cable. I had just removed the red wire from the "Y" on the side of the RX. Both engines turned ...
Remove the other two red wires from the "Y" side of the "ESCs" and only the motor that had the lipo connected was working.

[CraigP]

So as interesting as all this is, the main thing to keep in mind is to watch for unintended current flows in the ground, or minus side. All the electronics rely on the fact that the ground is electrically quiet for everything to work as designed. So I stick to the advice that dual setups should use what is essentially a 3-terminal capacitor, as I posted in the PDF on page 1 of this thread. This keeps the ground quiet. If your ESC’s both have opto-isolation and no BEC, then using that kind of cap with and external BEC will work well. The problem really comes in when you have LV ESC’s such as the T-180, that has an internal BEC. I have not seen a wire diagram that will hold down potential noise problems. I build a small PCB, that has a dual opto-isolator on it. Each channel is independent. I run a control cable from the receiver that provides the throttle signal, ground and power to both opto-isolator inputs. Then each ESC is hooked up to an opto-isolator output and that ESC’s BEC provides the power for the output side of its corresponding isolator. This completely eliminates ground and power loops, but you have to build it. I haven’t found a PC board on the Internet I can just buy. If I run across one, I’ll come back here and post the part number and source with a new PDF to wire it.

[golfito]

Very interesting!
I can try to build it the pcb.
I'm not an electronic technician, but I'm curious.

https://static.rcgroups.net/forums/attachments/1/3/7/0/6/a4171075-156-esc.JPG

I found it sailing ... would it be a combination of two of these circuits?

One question that occurred to me: futaba has the "DUAL ESC", some benefit in using two channels of the RX? instead of using a "Y"?

https://www.manualslib.com/manual/1201892/Futaba-4pls.html?page=74

I do not think the entries in the RX are isolated.

[golfito]

http://www.eastbayrc.org/TimTips/TimsTips_DualBatterySetups.htm

https://www.wr-store.com/index.php/optical-isolator-c-22?osCsid=gqhstg1n0q5pdq6i4l1t71q572

[CraigP]

Very interesting!
I can try to build it the pcb.
I'm not an electronic technician, but I'm curious.

https://static.rcgroups.net/forums/attachments/1/3/7/0/6/a4171075-156-esc.JPG

I found it sailing ... would it be a combination of two of these circuits?

One question that occurred to me: futaba has the "DUAL ESC", some benefit in using two channels of the RX? instead of using a "Y"?

https://www.manualslib.com/manual/1201892/Futaba-4pls.html?page=74

I do not think the entries in the RX are isolated.

The circuit is close. That’s a circuit diagram, used to show a configuration. It’s not an actual working circuit. If fact with using the battery directly, you could burn out the input on the ESC... They “usually” have an upper voltage rating of 7.5V. The second link is showing the capabilities of that transmitter to do Dual ESC Mixing, a powerful function in the world of twins! It allows you to speed modify the two motors based on rudder input. It’s a feature usually found on the better, more expensive radios. This does nothing for the electrical noise problem. Both ESC’s are still sharing a common control ground.

[CraigP]

http://www.eastbayrc.org/TimTips/Tim...terySetups.htm

https://www.wr-store.com/index.php/o...dq6i4l1t71q572

Nicely done Golfito!! The first link shows a solution under “Method 3, Power Domain Isolation, Opto Isolator”. The second looks like a viable part, but I like the cable layout better in the first link. It puts the opto isolator closer to the ESC, to help prevent noise pickup over the wire run. I would need to see the schematic of this part. I’m not sure how they are wiring the outputs on the opto isolator.

[CraigP]

It appears that West Mountsin Radio no longer makes that opto isolator. That leaves option 2. The east bay rc link on post #36 is in my opinion, a must-read for any FE guy! Loaded with good stuff!

[golfito]

I have a radio futaba and the necessary receiver ... do not use that function for recommendations in the FB, Elite RC B ...
I understand there is no noise isolation.
Also thinking about a kill swicht if it is possible that adapted work.

http://www.8fly.it/open2b/var/catalog/product/files/787.jpg

http://www.8fly.it/open2b/var/catalog/product/files/789.jpg

I hope you understand what I'm trying to describe.
https://hobbyking.com/en_us/opto-gas-kill-switch.html


And I found this:

http://www.mtroniks.net/prod/RC-Accessories/ZGM.htm#description

https://www.ebay.com/itm/D213-Opto-i...8AAOSw~XpZQAQq

http://rc.305.cz/view.php?cisloclanku=2015100004

https://www.ebay.com/itm/4-Channel-O...0477631?_ul=AR

[golfito]

https://drive.google.com/drive/folders/0B8i5PxQ5XywyZkFKankzVFVQOFU

These I can get in my city. Could it be used to build the circuit?
On Saturday I will try to ingest.

[srislash]

The circuit is close. That’s a circuit diagram, used to show a configuration. It’s not an actual working circuit. If fact with using the battery directly, you could burn out the input on the ESC... They “usually” have an upper voltage rating of 7.5V. .

Ah hah!!!!! I have been curious about this fact for awhile now but have not seen any manufacturer list specs. I would like to run a HV system but feared the ESC wouldn’t take it.

BTW guys this is a real good read. I have not experienced any of the loop issues but see room for improvement. Mmm, did lose one side of a twin ESC once mind you with no real cause

[golfito]

4_channel_opto_isolator_ic_module_3.jpg

This is more approximate. I think it could be useful.
I also followed the advice and link the ground wires of both ESCs.
26913508_1784045318563868_2029584755_n.jpg

[CraigP]

Let me draw you a schematic tomorrow. These aren’t showing enough detail. The previous post wasn’t quite right either. You did connect your grounds together in the picture, that’s good. But I don’t think that the forum in general understands the difference between wires and flat plat conductors. It’s just too deep a discussion for this forum, I’m only going to be ridiculed, so I’m not going to explain. Just know there is a big difference! I’ll just continue to build my cap banks in a manner that makes the most sense to me. Not trying to be difficult, it’s just a matter of choice. Your on a good path, I really like your quest to know more. But the open forum just doesn’t work for me. If you want, you can PM me an email address and we can take this discussion elsewhere. In fact, please do that first and I’ll send the schematic to your email. Thank Golfito, look forward to direct communication!

[golfito]

You are very kind. Thank you.
I will send you a private message.