ESC Separation

[Ken Culbertson]

I am building an electric twin with both esc's in the fuselage.  I don't get any responses on any other forum but main so I will ask my questions here.

Do the esc's need to be separated physically and can a single on/off switch be used.  I have pictures on my build thread but I will post one here as well.  Also, is 3/4" separation from the battery sufficient.

Ken

[spare_parts]

As is typical in multi ESC with BEC setups, you only use one BEC. The manual tells you multi motor models only need one BEC switched on. If an ESC doesn't have a power switch the manual will tell you to remove the positive lead in the radio lead for the same result. You can't run two voltage regulators (BEC) in parallel on the same circuit without more components.

[Ken Culbertson]

As is typical in multi ESC with BEC setups, you only use one BEC. The manual tells you multi motor models only need one BEC switched on. If an ESC doesn't have a power switch the manual will tell you to remove the positive lead in the radio lead for the same result. You can't run two voltage regulators (BEC) in parallel on the same circuit without more components.

I am a bit confused.  Since we have no receiver/servos, etc we have no need for a BEC other than to provide power to the timer.  So my question changes.  Since the Spin 33 does have a BEC does hooking up two ESC's to a Fiorotti timer require clipping the red wire on the second one or is the power pin on the second one disabled at the timer.  I seem to remember the timer not working if a single ESC is plugged into the ESC2 slot on the timer which leads me to believe that timer power always comes from ESC1 and ESC2 is blocked off.  I would much prefer to not roast my timer.

Ken

[spare_parts]

I was trying to address various circumstances. Most ESC do not have a switch for BEC, is which case isolation is handled another way. Always refer to the manual of your equipment. BEC usage has been covered in manuals ever since I started with electric in the 90's.

In your case you only have to switch on one ESC. Your "radio gear" consists of whatever you connect to the ESC servo lead. In virtually all cases, the power bus ( + , - ) is common.

I would have expected this to be detailed in the timer manual, but it was not in what I found. This is easy enough to test by switching on only one ESC. Even if you find you need to switch on both ESC don't combine those leads, I don't know what would happen. Use a double pole switch if you want one switch.

[Ken Culbertson]

I was trying to address various circumstances. Most ESC do not have a switch for BEC, is which case isolation is handled another way. Always refer to the manual of your equipment. BEC usage has been covered in manuals ever since I started with electric in the 90's.

In your case you only have to switch on one ESC. Your "radio gear" consists of whatever you connect to the ESC servo lead. In virtually all cases, the power bus ( + , - ) is common.

I would have expected this to be detailed in the timer manual, but it was not in what I found. This is easy enough to test by switching on only one ESC. Even if you find you need to switch on both ESC don't combine those leads, I don't know what would happen. Use a double pole switch if you want one switch.

This is what I need! - Thanks

[John Rist]

If I understand what you want to do and looking at your wiring diagram the following drawing is what I think you need.  You need a double pole switch to turn on both ESC.  However you need to connect only of the ESCs red wires to the Fiorotti timed.  This way the timer gets power form only one of the BEC in the ESCs.  You do not want to connect two BEC together.

Hope this is correct and it helps.

[Ken Culbertson]

If I understand what you want to do and looking at your wiring diagram the following drawing is what I think you need.  You need a double pole switch to turn on both ESC.  However you need to connect only of the ESCs red wires to the Fiorotti timed.  This way the timer gets power form only one of the BEC in the RSCs.  You do not want to connect two BEC together.

Hope this is correct and it helps.

That is pretty much what I will do.  So many wires, so little space!  I will cut the red wire on #2 even though I am pretty sure that pin is dead on the Fiorotti #2 ESC port.  I didn't think of the possible cross over problems with the power switch.  Thank both of you for pointing it out.  If I am understanding some of this the ESC gets it's power directly from the battery and the switch is just for the BEC?  In that case I only need a switch on ESC#1.

I have experienced putting power to a system wired wrong and I do not want to do it again!

Ken

[John Rist]

If I am understanding some of this the ESC gets it's power directly from the battery and the switch is just for the BEC?  In that case I only need a switch on ESC#1.



Ken

I don't think this is true.  Each ESC has a BEC built in.  The ESC get  power from the battery.  The main amount of power goes to the motor. The motor needs all of the 14 VDC  provided by the 6 S battery.  However the ESC has  tons of electronics that needs 5 VDC to operate   Each internal BEC in a ESC provides this 5 volts.  However it also buts this 5 volts on the red lead of the 3 wire connector going to the timer. This is where the timer gets it's 5 volts to operate.  Both BEC need to be turned on to power the internal electronics contained therein..  However only one of the BECs is connected to the Timer and the two BEC should not be tied together.

[Carl Cisneros]

KEN

do not cut the red wire that you want to on one of the plugs............

carefully lift the little locking tab that holds the red wire in the servo plug (of you will)
and pull that red wire out of the plug and fold it back onto the wiring to that plug and tape it in place.

that way you do NOT destroy the wiring to the esc servo lead.

I have always done this with my twim drive racing boats.

Carl

[John Rist]

I am not totally sure but I think you can eliminate the ON OFF switches.  I would think that you could hard wire the switches to the ON position.  That way when you insert the arming plug every thing will power up.  Most of the cheep ESCs I use do not have an on off switch.  Just a thought.  I don't have any experience with your brand of ESC.

[spare_parts]

The Jeti Manual clearly states:

Code: [Select]

6.2 Multi motor models
We recommend to use the same controller type for each motor. In case of SPIN controllers switch on
only one BEC. The switches of the other controllers remain in the “SWITCHED OFF” position.
When using controllers with BEC it is generally necessary to use only one common flight battery. If we
want to to utilize 2 and more batteries these must be connected in parallel.

No extra work is needed. No need to depin or cut 5V in the leads for these ESC.

I am not totally sure but I think you can eliminate the ON OFF switches.  I would think that you could hard wire the switches to the ON position.  That way when you insert the arming plug every thing will power up.  Most of the cheep ESCs I use do not have an on off switch. 

This is acceptable. You could remove the switch and insulate the wires on one ESC.

If in doubt about the 5V bus on the timer, check it. The PCB in the photos looked like the 5V was connected in all slots.

[Ken Culbertson]

I am not totally sure but I think you can eliminate the ON OFF switches.  I would think that you could hard wire the switches to the ON position.  That way when you insert the arming plug every thing will power up.  Most of the cheep ESCs I use do not have an on off switch.  Just a thought.  I don't have any experience with your brand of ESC.

I agree but I like the added safety/confirmation that the timer is powered by turning on the switch.  All my planes have them so I want the same takeoff ritual regardless of the plane I am flying.

Ken

[Doug Moon]

NVM i see what i was looking for

[John Rist]

The Jeti Manual clearly states:

Code: [Select]

6.2 Multi motor models
We recommend to use the same controller type for each motor. In case of SPIN controllers switch on
only one BEC. The switches of the other controllers remain in the “SWITCHED OFF” position.
When using controllers with BEC it is generally necessary to use only one common flight battery. If we
want to to utilize 2 and more batteries these must be connected in parallel.

This makes sense.  By turning on only one BEC and letting it dack feed the the other BEC and the timer all is good.  No need to disconnect anything.  The unused ON OFF switch and wire can just be left in the OFF position and tucked away out of sight.  All is good in river city.   

[Ken Culbertson]

You guys have been a real help and probably saved me replacing at least one ESC and maybe the timer.  I would still like to know if the pin for the red wire on the ESC#2 connection to a Fiorotti timer is hooked to anything.  It may be the power out for the Jeti-box.

Ken

[Ken Culbertson]

If I understand what you want to do and looking at your wiring diagram the following drawing is what I think you need.  You need a double pole switch to turn on both ESC.  However you need to connect only of the ESCs red wires to the Fiorotti timed.  This way the timer gets power form only one of the BEC in the ESCs.  You do not want to connect two BEC together.

Hope this is correct and it helps.

John:
I was comparing my diagram to yours and there is an important difference.  You show the ESC BEC wires joined and then going into the Fiorotti in, I assume, the top set of pins.  Did you intend that?  Everything I have found out is that #1 goes to the top set of pins and #2 with the red power wire disabled goes to the bottom set of pins.

Ken

[spare_parts]

You guys have been a real help and probably saved me replacing at least one ESC and maybe the timer.  I would still like to know if the pin for the red wire on the ESC#2 connection to a Fiorotti timer is hooked to anything.  It may be the power out for the Jeti-box.

Ken

The positive pins are connected and a multimeter would easily verify. If the Jeti box gets it's power from the servo lead (not it's own battery), that's proof enough.

[Ken Culbertson]

It gets it from the BEC cable when it is connected to the ESC which creates a Catch 22.  if I cut it for the timer I won't be able to program ESC#2.  Time for a custom plug between ESC#2 and the timer.  As many twins as there are out there now I will bet there are folks who have done this.  Bet they are sitting back laughing to see if we get it right!
I usually put a disconnect on the timer lead anyway so making one that doesn't have a power wire is what I will do.

It's fun learning this stuff!   

Ken

[Ken Culbertson]

I finished wiring.  This is how it is actually wired.  Before applying power - any comments?

Ken

[John Rist]

If ESC 2 ON/OFF switch is in the OFF mode (the two leads not touching) ESC 2 will not come on.  That is because you show  the red lead being cut that goes to ESC 2. ESC 2 needs 5V power.  It should come from it's internal BEC or be back fed from ESC 1 red wire.  So if BEC #2 is OFF and the BEC lead from ESC 1 is cut,  ESC 2 has no 5V power and will not work.

My first choice would be to leave ESC 2 switch in the OFF mode and not cut the red wire.

I have not not worked with the ESCs and timer you are using so I may be all wet.  But this is how it looks to me.

[Ken Culbertson]

From what I have read and surmised, the Fiorotti timer gets it's power from the red wire from ESC #1.  It has a separate port for ESC2.  Everywhere else I look says cut the red on BEC #2 to the timer BUT, when you plug a Jeti Box into the timer it goes on BEC #2 which is the 3rd set of pins..  It gets it's power from the center pin on the third set.  So, if the timer is providing 5v power on Pin #2 to the Jeti Box should it also provide power to the low voltage functions of ESC#2.
 I think the answer is no but I am waiting on someone who has used this timer to weigh in.  No powering on anyting till I know for sure.

Ken

[John Rist]

If I am right it won't hurt anything to power it up.   You can run electric motors with ought props. so for safety remove the props.  If both motors run all is good.  If motor # 2 doesn't run then ESC 2 is not getting 5 volts.  I guessing that the information you are reading is assuming that both ESC have the ON/OFF switches in the ON position.  In this case the red lead to ESC 2 is cut to prevent the BECs in ESC 1 & 2 from interfering wit each other.

Per you wiring diagram the timer gets it's 5 volt power from ESC 1 when it's ON/OFF switch is turned ON. .  ESC 2 has no source of 5 volt power. ESC 2 ON/OFF switch is OFF and the red lead from the timer is cut.  I am almost sure that power (red) and ground (black) power pins on the Fiorotti's ESC ports 1 & 2 are common. In fact the signal pins probably are also common.
As always free  information is worth what it cost you.   

[Ken Culbertson]

 

If I am right it won't hurt anything to power it up.   You can run electric motors with ought props. so for safety remove the props.  If both motors run all is good.  If motor # 2 doesn't run then ESC 2 is not getting 5 volts.  I guessing that the information you are reading is assuming that both ESC have the ON/OFF switches in the ON position.  In this case the red lead to ESC 2 is cut to prevent the BECs in ESC 1 & 2 from interfering wit each other.

Per you wiring diagram the timer gets it's 5 volt power from ESC 1 when it's ON/OFF switch is turned ON. .  ESC 2 has no source of 5 volt power. ESC 2 ON/OFF switch is OFF and the red lead from the timer is cut.  I am almost sure that power (red) and ground (black) power pins on the Fiorotti's ESC ports 1 & 2 are common. In fact the signal pins probably are also common.
As always free  information is worth what it cost you.   

What you are inferring is that the BEC power switch powers more than the BEC.  The Jeti manual says only one BEC should be turned on.  If the timer gets power from ESC#1's BEC cable both ESC's should get instructions from the timer.  Since the Jeti box is powered by the center pin on the ESC#2 port on the timer I have to assume that it is sending the 5v out from the timer.  Sending  5v in on the same wire could be interesting.  DC only flows one direction.  Sad part is that we have three of the best IC motor types in our flying group.  Too bad electrics don't use a spray bar! 

I was in EOD for a short time in the Air Force.  You NEVER cut the red wire.  Doing it here was traumatic.

Ken

[spare_parts]

The 5V bus doesn't care which direction current is flowing. The pins are in parallel. This is a non-issue.

[Fred Cronenwett]

that looks correct, the only change I would make is to use an ESC with BEC. And like stated above only one ESC needs to be powered with the main flight battery.  The 2nd ESC would have the red wire cut (power), but I would check that out on the bench first with the timer.

Also moving the ESC and the battery together into the fuselage is a smart move. You can extend the three motor wires but you don't want to extend the power wires. Looks like you are using one battery so that means you need to double the Mah rating on the battery to account for two motors pulling the amps out of the battery.

With my B-29 which has the Lipo's on each of the nacelles I have a separate ESC and battery for each motor. All four ESC's have BEC and all are connected to the same 2.4 Ghz reciever for throttle control. Only one ESC has all three wires plugged into the reciever, the other three only have the signal and ground wire plugged into the reciever. I can plug the #1 thru #3 batteries to the ESC and nothing happens, but when I plug the battery to the #4 ESC it powers up the reciever and it becomes armed.

Fred

[Ken Culbertson]

that looks correct, the only change I would make is to use an ESC with BEC. And like stated above only one ESC needs to be powered with the main flight battery.  The 2nd ESC would have the red wire cut (power), but I would check that out on the bench first with the timer.

Also moving the ESC and the battery together into the fuselage is a smart move. You can extend the three motor wires but you don't want to extend the power wires. Looks like you are using one battery so that means you need to double the Mah rating on the battery to account for two motors pulling the amps out of the battery.

With my B-29 which has the Lipo's on each of the nacelles I have a separate ESC and battery for each motor. All four ESC's have BEC and all are connected to the same 2.4 Ghz reciever for throttle control. Only one ESC has all three wires plugged into the reciever, the other three only have the signal and ground wire plugged into the reciever. I can plug the #1 thru #3 batteries to the ESC and nothing happens, but when I plug the battery to the #4 ESC it powers up the reciever and it becomes armed.

Fred

Thanks Fred.  I am using a Jeti 33 so both of them have the BEC built in.  I am going to shorten the BEC cable and connect to the timer via a patch cable.  The stock BEC cables on the Jeti are over a foot long and the timer is only 3" from the ESC's.  The two smaller motors (BadAss 2320's) have about the same draw as the one 3520 I am flying now so I get to use the same battery!   I really like tinkering.  The plane is getting the logarithmic flaps and a 5" bellcrank as well! 

Putting everything but the motors in the fuselage came from Bob Hunt.  I had originally designed it with long nacelles to house the ESC's with the battery pretty far back to shorten the leads.  Bob convinced me that having it all in fuselage would use less wire since the motor wires are much thinner and I could move the motors closer to the wing LE.  So I listened!  Imagine that.  He builds very light so I am trying to keep the weight down for fear that I might be under powered.  However according to Bob the smaller motors running a smaller prop can be run using slightly less RPM and still produce more power than a single motor because of the approximately 40% increase in the area covered by the props going from One 11" to two 10".  Sure hope he is right!

[John Rist]

Have you fired it up?  What was the final setup and is all good?

[Ken Culbertson]

Have you fired it up?  What was the final setup and is all good?

Final resolution was to "cut" the red wire on BEC #2 (per Jeti) and still undecided on the power switch for ESC #2.  Right now it is off but some (RC Types) say it should be wired permanently ON.  I feel very strongly both ways!

Won't fire it up for a while.  Starting on the wing.

Thanks for asking - Ken

[John Rist]

Final resolution was to "cut" the red wire on BEC #2 (per Jeti) and still undecided on the power switch for ESC #2.  Right now it is off but some (RC Types) say it should be wired permanently ON.  I feel very strongly both ways!

Won't fire it up for a while.  Starting on the wing.

Thanks for asking - Ken

It should be safe to fire it up with the red wire cut on BEC #2 and have  the power switch for ESC #2 OFF.  I feel certain that what will happen is that motor #1 will run and motor #2 will not run until you wire #2 OM/OFF switch ON.

A third option is to wire both ON/OFF switches (#1 & #2) to ON and cut the red wire to #2..  This way everything arms when you insert the arming plug.  The flight sequence starts when you push the start button on the Fiorotti timer.  If it were mine this is how I would do it.

The ON/OFF switch on the  Jeti ESC is primarily for use in a RC setup.  The RC folks, more often than not, do not have a arming plug.  They turn on there Tx.  They then plug up the battery with the Jeti ON/PFF switch OFF.  When they get ready to fly they turn the Jeti ON/OFF switch to ON.  This fires up the 5 volt BEC in the Jeti ESC.  This 5 volt power then gets disturbed to the receiver and all of the servos via all of the red wires.  The receiver then sends the Tx signal to the Jeti.  The Jeti  looks for the incoming throttle signal of "Motor OFF",  If it is Off the Jeti arms itself and the throttle stick on the Tx is in control of the motor.

In a U-control setup the Fiorotti timer takes care of all of this stuff.  So all that is needed is for the system to power up when you insert the arming plug.  Every thing is now ready to go.  All is waiting for instructions from the Fiorotti timer.  The Fiorotti timer, when power is applied, send out a motor OFF signal witch arms the Jeti. The Fiorotti timer then starts the flight sequence when you hit the Fiorotti timer start button.  So as I see it you don't need ON/OFF switches on the Jeti ESCs.  They can both be wired ON.  I have done a lot of work with both RC and U-Control electric.  I have not ever used a Fiorotti timer or a Jeti ESC.  But all of this stuff works under the same rules established by the RC world.

Looking forward for a flight report.

[Ken Culbertson]

John, I am leaning that direction.  I have gotten used to the double safety of the switch but you are right, it is redundant.

Ken