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May 02, 2013, 01:50 AM
Registered User
Quote:
Originally Posted by MEGAjig
...I have a hobby king 40-50A Opto ESC and currently I run a separate battery pack for the RX. I took the red wire out of the connector coming from the ESC to the RC just to be sure there is no power going through it. My setup works well ...
If your setup is working with the ESC's red wire to the receiver disconnected, then that ESC is not an opto -- never mind how HK label it. A true opto ESC needs 5v power from the receiver, via the red and black wires, to operate, as well as power from the main motor battery. That's because the input and output parts of the control circuitry are electrically isolated from each other (to prevent interference between them), so can't share the power from the motor battery.

The advice about disconnecting the red wire is only when the ESC has a built-in BEC and you're using a separate power supply -- either a stand-alone BEC or a standard Nixx receiver battery. It's to avoid the possibility of the two separate power supplies interfering with each other, and possibly causing damage.

Quote:
Originally Posted by MEGAjig
... How exactly do I wire in an external UBEC to eliminate the need for the RX pack?
Do I just solder on the positive and negative leads coming from the UBEC directly to the positive and negative leads that connect from the ESC to the battery?

Thanks
Yes, you connect the stand-alone BEC's input leads to the main ESC battery leads, then you plug the BEC's output into any spare slot in your receiver. If you have no spare slot, you can Y-lead it so it shares a slot with something else -- doesn't really matter what. Just make sure your BEC's input is rated for whatever voltage (cell-count) motor battery you're using.
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May 02, 2013, 07:31 AM
Retired in NC
Rich in ILM's Avatar
I am going to split hairs here and say an ESC can be "OPTO" and still supply it's logic circuit the 5v required. OPTO simply means that there is electrical isolation at the throttle input from the ESC provided by optical coupling. In the real world my guess is calling an ESC OPTO that doesn't require an outside 5v supply is bs.
May 02, 2013, 09:48 AM
Registered User
I take your point ... it could opto-isolate the signal and still get its power supply for all parts of the circuit from the motor battery

But that would be adding complication (an opto-isolator instead of a straight wire connection for the signal) and would defeat the objective in the case of our ESCs.
May 02, 2013, 11:40 PM
Registered User
Quote:
Originally Posted by abenn
I take your point ... it could opto-isolate the signal and still get its power supply for all parts of the circuit from the motor battery

But that would be adding complication (an opto-isolator instead of a straight wire connection for the signal) and would defeat the objective in the case of our ESCs.
Actually it could not, an optical isolation chip needs power from both sides, from the source to run the tiny LED and from the destination to convert the light back into an electrical signal.
May 03, 2013, 02:01 AM
Registered User
Quote:
Originally Posted by desertstalker
Actually it could not, an optical isolation chip needs power from both sides, from the source to run the tiny LED and from the destination to convert the light back into an electrical signal.
In practice, for our purposes, that has to be the case in opto ESCs.

But Rich's post #17, and my #18, were talking about in-theory: In theory there's nothing to stop you powering both sides of an opto-isolator from the same voltage source -- it defeats the primary objective of the isolator, but you can do it, and maybe in some applications there's good reason to do it, but not in RC ESCs
May 05, 2013, 07:04 PM
"I landed it"
MEGAjig's Avatar
so... what you're telling me is that even though I have a separate battery source powering my Rx I should put the red lead back into the Rx from the ESC?

When I purchased the ESC I didn't buy it because it was Opto. I actually found that out after. I always planned on running an external power source. I was just looking for a cheap high A ESC. This is the one I am referring to. https://www.hobbyking.com/hobbyking/s...idProduct=6459

HK PRODUCT ID: HK-SS50A (incase link doesn't work).

Thanks for the help
May 05, 2013, 07:38 PM
Retired in NC
Rich in ILM's Avatar
Quote:
Originally Posted by MEGAjig
so... what you're telling me is that even though I have a separate battery source powering my Rx I should put the red lead back into the Rx from the ESC?

When I purchased the ESC I didn't buy it because it was Opto. I actually found that out after. I always planned on running an external power source. I was just looking for a cheap high A ESC. This is the one I am referring to. https://www.hobbyking.com/hobbyking/s...idProduct=6459

HK PRODUCT ID: HK-SS50A (incase link doesn't work).

Thanks for the help
You will need the red wire from the receiver to the ESC.
May 05, 2013, 09:53 PM
Senile Member
Lnagel's Avatar
Quote:
Originally Posted by MEGAjig
so... what you're telling me is that even though I have a separate battery source powering my Rx I should put the red lead back into the Rx from the ESC?
Have you run the system with the red wire disconnected? If you did, and it worked, it is not a true opto ESC and there is no need to put the red wire back in. If it didn't work, it is most likely a true opto ESC and you have to reinstall the red wire.

Hobby King's description is rather ambiguous. It doesn't say outright that it is an opto ESC. But the description does say "BEC: Opto Only" which does not make any sense. As far as I know there's no such thing as an Opto Only BEC.[/QUOTE]

Larry
May 06, 2013, 02:15 AM
Registered User
Quote:
Originally Posted by Lnagel
Have you run the system with the red wire disconnected? If you did, and it worked, it is not a true opto ESC and there is no need to put the red wire back in. If it didn't work, it is most likely a true opto ESC and you have to reinstall the red wire. ...
Agreed
May 06, 2013, 03:33 AM
Retired in NC
Rich in ILM's Avatar
If you look at the picture it gives no voltage or current rating for the BEC.

Also, if you read the reviews there are several that mention the need for separate power. Here is one from somebody that didn't know what an opto meant:

"I bought this ESC thinking it would be like every other ESC I've used and i discover that the bloody thing doesn't even supply power to the receiver!!! I cant afford to weigh the jet down with more batteries!! This idea of no 'BEC' is crap in my opinion!"
May 06, 2013, 09:16 AM
Senile Member
Lnagel's Avatar
Quote:
Originally Posted by Rich in ILM
If you look at the picture it gives no voltage or current rating for the BEC.
That's what I meant about the description being ambiguous. It doesn't say no BEC, it says Opto Only. What the **** does that mean?

Larry
May 06, 2013, 11:28 AM
"I landed it"
MEGAjig's Avatar
I have run the system without the red wire and everything works great. Perhaps this isn't a "true" Opto ESC which is fine with me as I wasn't expecting it to be.
My Phoenix 2000 is really overloaded so I am now trying to reduce weight. I have about 320g of weight in batteries on it now (2200 3s and 4 AA to power the receiver) and I will get it down to 156g (1800 3s) and an 11g UBEC. I also flew it with another 200g+ in camera gear. That was a challenging flight.
May 07, 2013, 09:32 PM
Retired in NC
Rich in ILM's Avatar
Okay I was able to get to the shop and found a Hobby Wing Pentium 60 amp OPTO. I can tell you that this ESC DOES NOT need the red wire. It won't power the receiver, as expected, but it supplies all the power to it's own logic. I wonder if this the norm?
May 08, 2013, 02:08 AM
Registered User
Several of the far-eastern suppliers seem to use "opto" as a term to mean "no BEC". I've read the same about some of the HK ESCs.
May 20, 2013, 12:43 PM
Registered User
so lets say i need 6 esc's. My flight controller has external power, i just need one esc with bec to power receiver and the rest are bed-less or is that the same as an opto...? will an opto esc give out any bec type power?


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