I thought this subject had been covered in this Forum, but on checking found little info..so I went digging and found this decent article..
http://www.rcgroups.com/forums/showthread.php?t=952523
Some times it's necessary to lengthen the wires on the ESC ....and if so it should be done on the wires that lead to the motor and NOT the wires that lead to the battery. Having said that, if it is absolutely necessary to lengthen the wires of the ESC that lead to the battery, yes, I have gotten away with a four inch lengthening without adding additional capacitors to the ESC, but generally if you add wire to this end of the ESC you should be adding additional capacitors as well.
As for the small gauge Rx wire..no problem lengthing it...I have seen ESC's with a 14 inch Rx lead.
The above link covers the subject quite well and has pictures..!
Bill
ESC wires..Can I lengthen them...?
-
retiredVTT
- Posts: 5601
- Joined: Wed Oct 01, 2008 9:59 pm
- Location: Bedford, NS,CANADA
- Contact:
ESC wires..Can I lengthen them...?
Bill
HEFA #5
MAAC #13708
HEFA #5
MAAC #13708
-
RocketManRC
- Posts: 1285
- Joined: Wed Oct 01, 2008 9:39 pm
- Contact:
Re: ESC wires..Can I lengthen them...?
I would be very cautious with lengthening the "Rx wire". Unless using an external BEC, this cable supplies power to the whole radio system including the servos. So whether you can safely lengthen the cable or not depends on a whole lot of factors such as the capabilities of the ESC and the number and type of servos.
My personal recommendation is to use an external BEC if there is any doubt at all. The 10A Castle BEC is $23 and inexpensive insurance against having radio problems.
Rick
My personal recommendation is to use an external BEC if there is any doubt at all. The 10A Castle BEC is $23 and inexpensive insurance against having radio problems.
Rick
Rick MacDonald
May you live in interesting times!
May you live in interesting times!
-
saboo
- Posts: 597
- Joined: Mon May 18, 2009 3:48 pm
Re: ESC wires..Can I lengthen them...?
When lengthening the Battery to ESC wires some vendors recommend adding capacitors for every 6" you add beyond the original. The type is important as well. They must be the same voltage and value and the type usually has to be "Low ESR" type. ESR means equivalent series resistance. I have had to special order them locally or get them from DigiKey.CA
When making the wires longer it is best to use a one piece continuous length soldered directly to the ESC rather than putting in a joint. Then twist them tightly together starting at the ESC. When you put the battery connection on with the twist already in the wires, they tend to stay twisted. If in doubt add a short length of shrink wrap part away along the length, covering both wires, and another at the connector end to retain the twist.
When making up longer wires from the ESC to the Rx you should also start with full length new pieces as well to avoid joints. With longer ESC to Rx wires it is important to not use flat ribbon wire. As well because of the length use a larger gauge wire. You should be able to buy 22 gauge twisted servo wire locally. If the ESC was sufficient to power the servos and Rx with a short wire from the ESC to Rx, it will still be sufficient with longer wires of suitable gauge.
The use of twisted wires from the ESC to the Rx is a good policy. It reduces the electrical noise transmitted by the ESC through the flat wires. The flat wires act as an antenna. Twisted wires reduce this dramatically.
If you are using an external BEC as well as an ESC that has a built in BEC you must remove both the Positive and Ground wires from the ESC. You should only have the signal wire going from the ESC to the Rx. Remove the GND and + wires from the connector at the Rx end. If you use the Ground wire there is a risk of a ground loop which will destroy the Rx and usually the ESC.
When making the wires longer it is best to use a one piece continuous length soldered directly to the ESC rather than putting in a joint. Then twist them tightly together starting at the ESC. When you put the battery connection on with the twist already in the wires, they tend to stay twisted. If in doubt add a short length of shrink wrap part away along the length, covering both wires, and another at the connector end to retain the twist.
When making up longer wires from the ESC to the Rx you should also start with full length new pieces as well to avoid joints. With longer ESC to Rx wires it is important to not use flat ribbon wire. As well because of the length use a larger gauge wire. You should be able to buy 22 gauge twisted servo wire locally. If the ESC was sufficient to power the servos and Rx with a short wire from the ESC to Rx, it will still be sufficient with longer wires of suitable gauge.
The use of twisted wires from the ESC to the Rx is a good policy. It reduces the electrical noise transmitted by the ESC through the flat wires. The flat wires act as an antenna. Twisted wires reduce this dramatically.
If you are using an external BEC as well as an ESC that has a built in BEC you must remove both the Positive and Ground wires from the ESC. You should only have the signal wire going from the ESC to the Rx. Remove the GND and + wires from the connector at the Rx end. If you use the Ground wire there is a risk of a ground loop which will destroy the Rx and usually the ESC.
Nothing like the smell of electrons in the morning 
-
RocketManRC
- Posts: 1285
- Joined: Wed Oct 01, 2008 9:39 pm
- Contact:
Re: ESC wires..Can I lengthen them...?
Castle recommends removing only the red wire from the ESC when using their BEC:
http://www.castlecreations.com/support/ ... _guide.pdf (see page 2)
If you search on "ground loops" related to ESCs you will find quite a bit of debate on this. There is a fine line between reducing the risk of ground loops versus causing problems with lack of a proper ground reference.
I use the Castle BEC and I follow their recommendations.
http://www.castlecreations.com/support/ ... _guide.pdf (see page 2)
If you search on "ground loops" related to ESCs you will find quite a bit of debate on this. There is a fine line between reducing the risk of ground loops versus causing problems with lack of a proper ground reference.
I use the Castle BEC and I follow their recommendations.
Rick MacDonald
May you live in interesting times!
May you live in interesting times!
-
saboo
- Posts: 597
- Joined: Mon May 18, 2009 3:48 pm
Ground loops clarified
Some interesting reading
http://fpv-japan.com/technical-info/fpv ... s/lang/jp/
http://fpvlab.com/forums/showthread.php ... 9a15564765
http://www.rcgroups.com/forums/showthread.php?t=1762380
http://wiki.openpilot.org/display/Doc/C ... are+Manual
General consensus is that the Gnd is not necessary on the ESC if another BEC is in use. There was some criticism of Castle in other posts for not mentioning Ground Loops and for Castle suggesting, in their diagrams, that people use what is considered less than optimal practice.
When you look at the ground issue the ESC has a common Gnd rail. It is tied to the Gnd of the battery. The separate BEC has a Gnd tied directly to the battery. The Rx now has 2 separate sources for Gnd one from the BEC one from the ESC. That is the definition of a Gnd loop. That definition can be summarized as "a device having more than 1 source of Gnd".
Everyone is free to use their own choice. I will follow the engineering first principles where a device with 2 ground sources has a Ground Loop. They are not recommended practice. YMMV.
http://fpv-japan.com/technical-info/fpv ... s/lang/jp/
http://fpvlab.com/forums/showthread.php ... 9a15564765
http://www.rcgroups.com/forums/showthread.php?t=1762380
http://wiki.openpilot.org/display/Doc/C ... are+Manual
General consensus is that the Gnd is not necessary on the ESC if another BEC is in use. There was some criticism of Castle in other posts for not mentioning Ground Loops and for Castle suggesting, in their diagrams, that people use what is considered less than optimal practice.
When you look at the ground issue the ESC has a common Gnd rail. It is tied to the Gnd of the battery. The separate BEC has a Gnd tied directly to the battery. The Rx now has 2 separate sources for Gnd one from the BEC one from the ESC. That is the definition of a Gnd loop. That definition can be summarized as "a device having more than 1 source of Gnd".
Everyone is free to use their own choice. I will follow the engineering first principles where a device with 2 ground sources has a Ground Loop. They are not recommended practice. YMMV.
Nothing like the smell of electrons in the morning
-
RocketManRC
- Posts: 1285
- Joined: Wed Oct 01, 2008 9:39 pm
- Contact:
Re: ESC wires..Can I lengthen them...?
Well I don't think there is any consensus at all Jim! Those first 3 references are for multicopters where there is a current sensor. In that case I totally agree that there is no choice but to remove the ground wire from the ESC cables as the wiring is a mess.
The last reference is for the CopterControl manual which I assume is for the system you have been using. In that document you will see the warning "In some rare cases or on high-end ESCs the ESC doesn't perform correctly without connecting the additional ground signal. In those cases it may be necessary to connect the ground wire to the ESC". The reason for that is what I mentioned earlier. You are removing the chance of ground loops but also the intended ground reference for the ESCs motor control signal.
In general it is not a good idea to mix signal and power grounds. So in the situation I was originally describing with one ESC and one BEC connected to a single battery, when you remove the ground wire from the signal cable to the ESC you are forcing the signal return to be the current carrying ground wire of the BEC. Not good practice! When you connect both ground wires then you still have the problem but only half as bad as you have twice the current carrying capacity in the return path now.
Also I would like to point out that when you use a separate battery for the ESC which is common for most of the larger helicopter setups, then you absolutely need to have both ground wires connected to the receiver or you will have a floating ground situation. This may even work on the bench but will be a disaster eventually.
As always, the devil is in the detail and there is no such thing as one approach is good for all...
The last reference is for the CopterControl manual which I assume is for the system you have been using. In that document you will see the warning "In some rare cases or on high-end ESCs the ESC doesn't perform correctly without connecting the additional ground signal. In those cases it may be necessary to connect the ground wire to the ESC". The reason for that is what I mentioned earlier. You are removing the chance of ground loops but also the intended ground reference for the ESCs motor control signal.
In general it is not a good idea to mix signal and power grounds. So in the situation I was originally describing with one ESC and one BEC connected to a single battery, when you remove the ground wire from the signal cable to the ESC you are forcing the signal return to be the current carrying ground wire of the BEC. Not good practice! When you connect both ground wires then you still have the problem but only half as bad as you have twice the current carrying capacity in the return path now.
Also I would like to point out that when you use a separate battery for the ESC which is common for most of the larger helicopter setups, then you absolutely need to have both ground wires connected to the receiver or you will have a floating ground situation. This may even work on the bench but will be a disaster eventually.
As always, the devil is in the detail and there is no such thing as one approach is good for all...
Rick MacDonald
May you live in interesting times!
May you live in interesting times!
-
MarkL
- Posts: 366
- Joined: Fri Sep 16, 2011 3:42 pm
Re: ESC wires..Can I lengthen them...?
If you have longer wires between the motor and ESC it is also a good idea to braid them as well, especially if your running FPV setup where noise can cause issues with the video feed.
-
saboo
- Posts: 597
- Joined: Mon May 18, 2009 3:48 pm
Re: ESC wires..Can I lengthen them...?
Quote from another user
"In general it is not a good idea to mix signal and power grounds. So in the situation I was originally describing with one ESC and one BEC connected to a single battery, when you remove the ground wire from the signal cable to the ESC you are forcing the signal return to be the current carrying ground wire of the BEC. Not good practice! When you connect both ground wires then you still have the problem but only half as bad as you have twice the current carrying capacity in the return path now."
End quote
This might not be quite correct. The signal line is a differential to a reference level. This reference level is present in the Rx and the Gnd in the ESC provides a continuation of this reference. There is no current flowing through this small gauge signal Gnd.
Another reason it may not be a valid belief is that when no external BEC is present, the Gnd line to the Rx from the ESC is both signal ground and power ground. This appears to be accepted practice to use the Power ground as a signal ground. So why would using a common ground for Power and Signal be acceptable without an external BEC and unacceptable with an external BEC? Without an external BEC no ground loop can be created unless you have 2 ESC.
Actually when you connect both wires you create the problem. The 2 wires does not double the current capacity as stated. They are not in parallel. They are in series and create the ground loop. The ground loop is created when the 2 wires connecting the 2 devices provide an alternate path for the power ground, typically the power ground supplying the high current of the motor. They become a series connection through the wires and traces of the ESC, the BEC and the Rx. Current carrying capacity is double if the lines are in parallel. The ground loop is created when the wires are in series and these lower gauge wires provide not just signal ground but are forced to be an alternate power ground line carrying the full motor current.
The Ground wire is connected directly to the ground internally in the ESC and the BEC in most generally available devices.
The reference to "High End" devices is referring to ESCs with optically isolated lines. The signal and ground line from these "High End" ESC are optically isolated and provide no DC to DC continuity between signal ground and power ground. This is to prevent the transfer of noise from the usually high power ESC. Therefore they cannot create a ground loop. As they are optically isolated the use of the ground wire is required. This signal Gnd wire, in optically isolated devices, is not connected internally to the power Gnd. Typically these "High End" ESC devices do not have a built in BEC that needs to be disabled.
Note that there would not normally be an optically isolated BEC. If the BEC is optically isolated then no power can flow through the Gnd line and thus no power to the Rx or servos. In fact the BEC has only power and Gnd, no signal and the BEC is a power supplying device where the Gnd has to be connected as well as the red power line.
A ground loop is not a risk until something else misbehaves. In most cases a ground loop can fry the attached equipment if the power ground has some form of issue, which issue forces the power current to flow through the 26g (22g, 30g etc ) wires and traces on the board of the ESC and BEC, and the signal ground of the ESC, and through the traces on the Rx. Result is usually instant death to the electronics and the aircraft if it is flight at the time.
It often appears as a fried ESC and "Oh yes it took out the Rx when it died". A good chance it was a ground loop that fried both at once. Same cause, motor current flowing through signal Gnd traces and low gauge Gnd wires.
I do not use CopterControl or fly rotary wing aircraft.
YMMV
"In general it is not a good idea to mix signal and power grounds. So in the situation I was originally describing with one ESC and one BEC connected to a single battery, when you remove the ground wire from the signal cable to the ESC you are forcing the signal return to be the current carrying ground wire of the BEC. Not good practice! When you connect both ground wires then you still have the problem but only half as bad as you have twice the current carrying capacity in the return path now."
End quote
This might not be quite correct. The signal line is a differential to a reference level. This reference level is present in the Rx and the Gnd in the ESC provides a continuation of this reference. There is no current flowing through this small gauge signal Gnd.
Another reason it may not be a valid belief is that when no external BEC is present, the Gnd line to the Rx from the ESC is both signal ground and power ground. This appears to be accepted practice to use the Power ground as a signal ground. So why would using a common ground for Power and Signal be acceptable without an external BEC and unacceptable with an external BEC? Without an external BEC no ground loop can be created unless you have 2 ESC.
Actually when you connect both wires you create the problem. The 2 wires does not double the current capacity as stated. They are not in parallel. They are in series and create the ground loop. The ground loop is created when the 2 wires connecting the 2 devices provide an alternate path for the power ground, typically the power ground supplying the high current of the motor. They become a series connection through the wires and traces of the ESC, the BEC and the Rx. Current carrying capacity is double if the lines are in parallel. The ground loop is created when the wires are in series and these lower gauge wires provide not just signal ground but are forced to be an alternate power ground line carrying the full motor current.
The Ground wire is connected directly to the ground internally in the ESC and the BEC in most generally available devices.
The reference to "High End" devices is referring to ESCs with optically isolated lines. The signal and ground line from these "High End" ESC are optically isolated and provide no DC to DC continuity between signal ground and power ground. This is to prevent the transfer of noise from the usually high power ESC. Therefore they cannot create a ground loop. As they are optically isolated the use of the ground wire is required. This signal Gnd wire, in optically isolated devices, is not connected internally to the power Gnd. Typically these "High End" ESC devices do not have a built in BEC that needs to be disabled.
Note that there would not normally be an optically isolated BEC. If the BEC is optically isolated then no power can flow through the Gnd line and thus no power to the Rx or servos. In fact the BEC has only power and Gnd, no signal and the BEC is a power supplying device where the Gnd has to be connected as well as the red power line.
A ground loop is not a risk until something else misbehaves. In most cases a ground loop can fry the attached equipment if the power ground has some form of issue, which issue forces the power current to flow through the 26g (22g, 30g etc ) wires and traces on the board of the ESC and BEC, and the signal ground of the ESC, and through the traces on the Rx. Result is usually instant death to the electronics and the aircraft if it is flight at the time.
It often appears as a fried ESC and "Oh yes it took out the Rx when it died". A good chance it was a ground loop that fried both at once. Same cause, motor current flowing through signal Gnd traces and low gauge Gnd wires.
I do not use CopterControl or fly rotary wing aircraft.
YMMV
Nothing like the smell of electrons in the morning
-
RocketManRC
- Posts: 1285
- Joined: Wed Oct 01, 2008 9:39 pm
- Contact:
Re: ESC wires..Can I lengthen them...?
I give up. LOL.
Rick MacDonald
May you live in interesting times!
May you live in interesting times!
-
retiredVTT
- Posts: 5601
- Joined: Wed Oct 01, 2008 9:59 pm
- Location: Bedford, NS,CANADA
- Contact:
Re: ESC wires..Can I lengthen them...?
Well, not any detail in the reply from Castle Creations regarding lengthening the small receiver wire that goes from the ESC....
Bill
Bill,
Lengthening the receiver wire is fine.
Dan Forbes
Product Specialist
Castle Creations
540 North Rogers Rd
Olathe, KS 66062
(913)390-6939 ext. 138
On 3/20/2013 3:46 PM, Bill Foster wrote:
Hi Guys, ..could you answer my question regarding lengthening of the Rx wire on an ESC.
thanks,
Bill
Bill
Bill,
Lengthening the receiver wire is fine.
Dan Forbes
Product Specialist
Castle Creations
540 North Rogers Rd
Olathe, KS 66062
(913)390-6939 ext. 138
On 3/20/2013 3:46 PM, Bill Foster wrote:
Hi Guys, ..could you answer my question regarding lengthening of the Rx wire on an ESC.
thanks,
Bill
Bill
HEFA #5
MAAC #13708
HEFA #5
MAAC #13708