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Old Jul 07, 2012, 10:28 AM
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St. Thomas, VI
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Question
HV servos, non-HV ESC ?

I have a couple of medium to large sized (.60 - 50cc) conversion projects coming up, and am thinking of going with HV power to the radio gear pretty much across the board. I figure that higher voltage == less chance of brownouts.

No more BECs or regulators - just one more component to fail. Done that, got piles of parts to prove it.

So there are HV-rated components which will allow me to run all the radio gear and servos straight off a 2S lipo with no problems. Other than pulling the (+) wire do I need to do anything to safely use a non-HV ESC? What about if I'm using an ESC with no internal BEC... do I still need to pull the red wire?
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Old Jul 10, 2012, 12:20 PM
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Australia, SA, Adelaide
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Originally Posted by visioneer_one View Post
I have a couple of medium to large sized (.60 - 50cc) conversion projects coming up, and am thinking of going with HV power to the radio gear pretty much across the board. I figure that higher voltage == less chance of brownouts.

No more BECs or regulators - just one more component to fail. Done that, got piles of parts to prove it.

So there are HV-rated components which will allow me to run all the radio gear and servos straight off a 2S lipo with no problems. Other than pulling the (+) wire do I need to do anything to safely use a non-HV ESC? What about if I'm using an ESC with no internal BEC... do I still need to pull the red wire?
I'm not sure, as I have never use hv before but you shouldn't need to worry.

If you have a multimeter or an oscilloscope, find out the voltage between signal and negative and compare that to normal voltage. If it is a massive change (greater than 1.25 times) try to find a hv esc.

Hope it helped,
Darcy
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Old Jul 10, 2012, 08:16 PM
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Canada, AB, Clairmont
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i am currently running a few systems that have the reciever and servos powered by a BEC set at 9.0 volts.

these systems use Castle Ice2 120 and 160HV ESC's (no internal BEC). I have not cut the red wire and have not seen any negative impacts of the 9.0volts going to the ESC through the signal wire from the reciever.

If your esc has a built in BEC, you will DEFINATELY want to cut the red wire though.

HV ESC is usually an endorsement of how much voltage the flight battery pack can be (usually over 6s is considered HV).... and not the voltage that is coming from the reciever..
That being said, there may be some ESC's that do not like more than 6volts on the signal wire??
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Old Jul 11, 2012, 04:22 AM
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Easiest solution is use ESC's with OPTO isolation. This means the lead going from the ESC to the RX is completely isolated, no voltage goes either direction on the lead. The only way to power the ESC is via the main battery leads. Another advantage of the OPTO is less chance of radio interference created by voltage back feeding into the RX. This is honestly the ideal solution.

If your ESC is not OPTO isolated, and definitely if it has a built-in BEC, then yes I would remove the red wire from the lead going to the RX. Since you are using a direct HV power source to the RX for the servos you don't want power coming from the ESC regardless.
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Old Jul 11, 2012, 05:29 AM
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But I think visioneer_one wants to know (and I do too) is it bad if 9v goes into signal wire of the esc which is designed to take a signal at 6v
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Old Jul 11, 2012, 05:32 AM
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But I think visioneer_one wants to know (and I do too) is it bad if 9v goes into signal wire of the esc which is designed to take a signal at 6v
If the ESC is OPTO then no it doesn't matter, because the RX lead is completely isolated and the voltage never reaches the ESC. If the ESC is not OPTO then more than likely it has a built-in BEC which means you will be removing the red wire regardless and it doesn't matter if the ESC can handle the 9V.

In other words, it's a problem that likely does not even exist.
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Old Jul 11, 2012, 10:14 AM
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Originally Posted by Anthony.L View Post
If the ESC is OPTO then no it doesn't matter, because the RX lead is completely isolated and the voltage never reaches the ESC. If the ESC is not OPTO then more than likely it has a built-in BEC which means you will be removing the red wire regardless and it doesn't matter if the ESC can handle the 9V.

In other words, it's a problem that likely does not even exist.
I am not talking about the +ve (red/brown) wire but the signal wire (white/yellow). Will the instantaneous potential difference between the signal and -ve (black) wire being 8.5v wreck the chip on the esc which are only ever (if made for normal voltages) designed for 6v?

From what I have heard OPTO can be left out of this argument as they are designed for OPTiOnal voltage and visioneer_one doesn't have that kind, just regular escs with the red wire removed.

Also I would like to ask that, on the opto the RX lead (I'm going to take that as the signal wire) is totally isolated, which is fine, but therefore no voltage (therefore no current either in DC) reaching the esc is wrong.

There are two reasons. First, have you every heard of a transformer? Without going into detail, the power source is isolated from the power sink yet Vsink=c*Vsource (where c is a predertermined multiplier, google for more info)and the source voltage is transferred (and mostly multiplied or divided) to the sink.

Secondly, how is the info from the rx get to the esc with out a medium to travel in? In this case the medium is voltage. If no voltage reaches the esc through the signal wire nothing is heard. Its like talking to someone in a total vacume (sorry for the spelling).

If I misunderstood you feel free to point out where and how, but for now,
Good day to You! (my best 18th century angry Englishman dismissal tone of voice)
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Old Jul 11, 2012, 11:36 AM
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St. Thomas, VI
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Originally Posted by Anthony.L View Post
If the ESC is OPTO then no it doesn't matter, because the RX lead is completely isolated and the voltage never reaches the ESC. If the ESC is not OPTO then more than likely it has a built-in BEC which means you will be removing the red wire regardless and it doesn't matter if the ESC can handle the 9V.
Thanks for the input.

I had a quick conversation with tech support at Castle and what you wrote here matches up quite well with the information they provided.

In short - any ESC with an on-board BEC needs to have the (+) lead disconnected. ESCs with no built-in BEC can safely be plugged in directly with no modifications.

(This applies to Castle ESCs, as they can tolerate up to 9.0V on the input lead.)

I'll be using a mix of HV and non-HV controllers. It sounds like the Castle branded gear will be OK. The Turnigy gear OTOH... more research needed !
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Old Jul 11, 2012, 11:39 AM
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Originally Posted by molond View Post
I am not talking about the +ve (red/brown) wire but the signal wire (white/yellow). Will the instantaneous potential difference between the signal and -ve (black) wire being 8.5v wreck the chip on the esc which are only ever (if made for normal voltages) designed for 6v?

From what I have heard OPTO can be left out of this argument as they are designed for OPTiOnal voltage and visioneer_one doesn't have that kind, just regular escs with the red wire removed.

Also I would like to ask that, on the opto the RX lead (I'm going to take that as the signal wire) is totally isolated, which is fine, but therefore no voltage (therefore no current either in DC) reaching the esc is wrong.

There are two reasons. First, have you every heard of a transformer? Without going into detail, the power source is isolated from the power sink yet Vsink=c*Vsource (where c is a predertermined multiplier, google for more info)and the source voltage is transferred (and mostly multiplied or divided) to the sink.

Secondly, how is the info from the rx get to the esc with out a medium to travel in? In this case the medium is voltage. If no voltage reaches the esc through the signal wire nothing is heard. Its like talking to someone in a total vacume (sorry for the spelling).

If I misunderstood you feel free to point out where and how, but for now,
Good day to You! (my best 18th century angry Englishman dismissal tone of voice)
You are WAY over thinking the problem (or as I pointed out, lack thereof). You must be an engineer...
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Old Jul 14, 2012, 11:08 AM
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Originally Posted by Anthony.L View Post
You are WAY over thinking the problem (or as I pointed out, lack thereof). You must be an engineer...
just finish my first semester a bachelor of aerospace and mechanical engineering. Man your good
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