Common caps for two escs?

[CraigP]

The connectors are wired to be compatible with Futaba style of wiring. My boards hooked right in. After changing the input resistance, it all worked good. I have them hooked up in series after the mixer board, and that works great.

I’m not sure what changing the output resistor does, other than load the ESC BEC a bit more. It’s not a big deal... The output transistor is in the Emitter Follower mode of operation. So the current to the ESC input is not governed by that resistor. It’s there to bias the emitter, nothing more.

It would be nice to see scope shots, but I understand not having one. You’re working blind! You have enough patience, that’s for sure!

[CraigP]

Invert the signal and ground wires at the output. Remaining the first circutito that I present. And it worked!

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Golfito, I fixed those errors you found in the schematics. Could you please check these and let me know if they look like what you built? Thanks!

[golfito]

Hello Craig, tomorrow I will try to assemble a plate and comment.
I am also trying to understand how to calculate in a practical way a capacitor bank. I am reading a very complete post in this same forum.

[CraigP]

Golfito, the most important thing about a cap Bank is the capacitors. You may have a problem getting good one there. You can use many, smaller caps to get around that. If you want me to look up specs on what you might use, I would be happy to help. Just let me know.. I got a new project I’m building too. I like building things!

[golfito]

Thank you very much. I also enjoy building.
The capacitor banks have already been assembled. Something generic. Not special. I just do not seem to follow advice correctly. And I exceeded a little in total capacity. 470ufx35v for 10 units each bank. http://www.nichicon.co.jp/english/products/pdf/e-hv.pdf
That's the only low ESR I could get ...
And the ESC T-180 brings 1000ufx35 for 3 units of Rubycon.
Total each ESC T-180 will have 7700uf. It will run a double motor, 6SP1, 5A 70C lipo, TP 4050 1700KV, X447.

[CraigP]

Yes, those are 1.8A@100Khz. So you got 10.... That should be pretty good. Looking good!

[golfito]

Hello, some other advance?
I will try to restart the assembly of a PCB board.

[golfito]

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[golfito]

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[golfito]

Well change the resistance from 1K ohm to 220 between the opto and the RX. With the TX flysky it worked, but not so with the radio futaba. But I'm using optos 4N35 and not the ps2501.

https://www.youtube.com/watch?v=e9RX46Xdvvk&feature=youtu.be

https://www.youtube.com/watch?v=8tLBYyz6IGs&feature=youtu.be

[CraigP]

I found the same thing, worked on one reciever but not another type. The PS2501 is a higher gain device than the 4N25, which was designed for slow switching and analog isolation circuits. It might give you trouble... The PS2501 worked very well going from 220 Ohm to 1K. Here’s a pic in my new boat, a UL-1. It’s in between the water lines, aft of the ESC. This is a single channel Opto Board.

[golfito]

I think I got a couple of ps2501-1 ... when they arrive I will try 1K on my RX futaba.

[Jamey]

Needs to be a conductor as big as the wire size going to the cap Bank. Just to let you know, round wires create external magnetic fields around them very easily. Those magnetic fields creates inductance, which is called “leakage inductance”, because it’s not directly coupled to a power source. This causes a loss and increases ripple current/voltage on the system. Flat copper plate does not create near as strong of an external field, so no leakage inductance. That reduces ripple... your wire helps, but you’ll still have quite a bit of ripple on that wire at currents over 120A.

Hi Craig, your discussion here has me interested! I normally build my cap packs on short pigtails w/8-10x 1000uf and it seems to work. Original caps built into the esc that used to run very hot now with the cap pack run cool. Hence my assumption they are working.

So talking single motor/esc, if I wanted to instead add 1 or 2+ of your 3600uf caps would it be better in your opinion to use the flat copper plate somehow as opposed to just soldering across the power wires close to the esc board? If so how would you do it? Thanks!

[CraigP]

Flat plate reduces the added inductance that wires make. It all depends on the current you are using. Flat plate starts to have a good advantage at 120A and up. I usually get 1/16” copper plate, cut it to the desired shape and drill holes into the plate to mount the caps. I attached some pics of a big, 350A cap Bank to give you a reference.

[Jamey]

Thanks man! So I assume you then skin back the power leads and solder to respective plates?