Two motors on one ESC

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10 October 2012 at 11:58 #36961
Trevor Holloway
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@trevorholloway99134
I am experiencing problems with connecting two suppressed motors in parrallel on one ESC – the rudder servo goes haywire (not sure if that is the correct technical term).

Have tried a couple of ESCs with the same result, when connected to a single motor there is no problem.

Should the motor cans be connected together (earthed) ?

Additional suppression because of the twin motors ?

Any other suggestions ?

Thanks
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10 October 2012 at 11:58 #5194
Trevor Holloway
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@trevorholloway99134
11 October 2012 at 08:07 #36973
ashley needham
Participant
@ashleyneedham69188
Trevor. All my twin engined boats are joined up as you say, in parallel and supressed, and on a Mtronics ESC dont give any trouble to the other departments,

When I do have trouble it is usually because of the aeriel wire picking up emissions..moving stuff about usually cures this. Twisting the motor wires together is a ploy, as is "earthing" the motors to the water, or using ferrite rings on the leads…but you shouldnt need any of this, its for extreme circumstances.

Which motors are you using?do you have any others just to connect up and try out?? I will bung a few in the tool box to try if you are down Sunday and have not fixed it by then.

Ashley
11 October 2012 at 08:19 #36974
Dave Milbourn
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@davemilbourn48782
Here is Chapter and Verse from an acknowledged authority on the subject

**LINK**

Dave M
11 October 2012 at 08:55 #36975
shipwright
Participant
@shipwright
Trevor – just a thought. Are you using BEC or a separate battery for the receiver ? If using separate battery you may need to remove the red lead from the connection between the ESC and Rx (see Mtronix instructions **LINK**&nbsp

Ian
11 October 2012 at 10:06 #36976
Trevor Holloway
Participant
@trevorholloway99134
From the "Chapter and Verse" it looks like I may need to earth the cans together and onto one prop tube.

As it is in a 1:40 Waveney lifeboat there is very limited space so I can not separate the receiver from the rest of the equipment, also there is no space for a receiver battery (only just enough room for 6 AAA rechargables) so am using the BEC.

Will add wires to cans for experimenting at the pond on Sunday so that the amassed experts can offer varied solutions !
12 October 2012 at 10:18 #36982
ashley needham
Participant
@ashleyneedham69188
More experts than you can shake a stick at !!

My RtR Severn works ok, and this is VERY small, so must be just something silly giving you the glitches.

Ashley
12 October 2012 at 10:21 #36983
Trevor Holloway
Participant
@trevorholloway99134
Probably the nut on the transmitter !
12 October 2012 at 12:42 #36986
Malcolm Frary
Participant
@malcolmfrary95515
Silly question time – does the problem happen with just one motor connected?

– are both motors supressed? – supression must be a close to the motor as possible.

It is possible that the interference is not RFI, it could just be wire to wire "overhearing", the field produced by the heavy current in the motor wires being picked up by the servo wiring (unlikely, but not impossible), or it could be the load produced by the motors changing the ground line voltage to the RX.

If adding extra bits of wire to a system to try to reduce interference, beware – they can pick up or transmit interfering signals, and make matters worse, or at least, more confusing.

"Haywire" is a reasonable technical term. Re-reading, I notice "6 AAA rechargeables". I have to wonder if the load of 2 motors is too much for the power supply. Supply voltage wandering due to load does cause servo jitter. It could be either the batteries not being man enough for the job in the first place, or a poor connection somewhere in the system, between cells, or between battery and ESC.
14 October 2012 at 18:12 #37029
ashley needham
Participant
@ashleyneedham69188
Looked at Trevors boat, made a few suggestions (which he had already tried ) and we thought that ferrite rings here and there might help, failing this, seperate the motor wiring and try each motor seperately. Although apparently the rig works with a.n.other motor, that is not the same as the motor wots fitted.

Trevor has tried this with a larger battery pack so its not the supply voltage that is the issue, although trying this with 6 Duracell batteries might be informative. The motors are very small and will well within the capability of some "ordinary" batteries.

The ESc is a small forwards only one, possinly an aircraft type….the brushless ESC I have came with its lead wrapped around a ferrite ring, so poss they are a bit susceptable.?

Ashley

Edited By ashley needham on 14/10/2012 18:15:19
15 October 2012 at 09:18 #37038
Trevor Holloway
Participant
@trevorholloway99134
Yup currently fitted with aircraft ESC but alos happens with a "tried and trested" marine forwards and reverse ESC too.

Will try isolating the motors and adding ferrite rings.
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