ESC wiring help

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15 September 2013 at 21:40 #43757
Mike Burgess 1
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@mikeburgess1
Hi all. I am just wiring up two motors with the Viper marine 15 speed controller x2 and fitting a W tail mixer from Mtronics. The question I need to know is do I fit both of the on / off switches or link them together. I am not using an external batter pack, just a receiver. Help would be much appreciated.
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15 September 2013 at 21:40 #4040
Mike Burgess 1
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@mikeburgess1
16 September 2013 at 10:10 #43773
Dave Milbourn
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@davemilbourn48782
Leave both switches intact.
Remove the Red wire from the plug of ONE of the speed controllers. Leave the plug on the other ESC alone. **LINK**
Use the switch on the ESC which you didn't modify as the radio On/Off switch. Leave the other switch ON all of the time.

Dave M
16 September 2013 at 10:49 #43775
Malcolm Frary
Participant
@malcolmfrary95515
The switch logically supplies power to the control part of the ESC. If the battery is disconnected between sessions (generally a good idea), yes, leave the "unwanted" switch permanently on, but if the battery is left connected, there will be a permanent discharge path with the switch on. Only a few mA, but over time it would flatten the battery.
16 September 2013 at 12:09 #43779
Dave Milbourn
Participant
@davemilbourn48782
It's never a good idea to leave a battery connected all the time unless you fit an isolator switch in the positive lead between the battery and the ESC. If you do this – which is to be recommended – then you can leave the small ESC switches ON because there will be no live circuits once the main battery switch/switches are off.
If all of this is a bit confusing then sit back and wait for a long and detailed article on model boat electrics in the forthcoming Model Boats Winter Special. All will be explained!
Dave M
16 September 2013 at 13:23 #43783
Gareth Jones
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@garethjones79649
I have the set up recommended by Dave in one of my models, i.e. one ESC is the master and supplies power to the receiver, the other ESC is the slave and has its red wire disconnected. If I leave the slave unit switched on when the power is switched off to the master, the motor supplied by the slave runs for a few seconds at quite a high rpm and then stops The transmitter is still on, with the throttle in the centre off position when this happens.

I dont know if it is significant but both Mtroniks ESC are connected to the receiver via an Mtroniks W tail mixer. The left hand throttle channel operates both motors together, forwards and reverse. The right hand rudder channel operates but motors differentially, i.e. one goes forwards, one backwards to steer the model. Again, by concidence the model will be described in a forthcoming Model Boats article.

However back to the original problem, I just have to remember to switch off the slave ESC first, the main ESC next and then I disconnect the battery which supplies both ESC. After that I turn the transmitter off.

Gareth
16 September 2013 at 20:43 #43795
ashley needham
Participant
@ashleyneedham69188
Gareth. Most interesting, as I will be , or at least, was planning to use exactly this setup in a forthcoming model and was wondering about the W tail mixer.

I have a very excellent "P" something twin esc unit from a well known manufactutrer and this works a treat, but is much too big for the next application.

Ashley
16 September 2013 at 21:08 #43796
Mike Burgess 1
Participant
@mikeburgess1
Hi. Many thanks for the info I now know what to do
17 September 2013 at 00:10 #43799
Dave Milbourn
Participant
@davemilbourn48782
Ashley

Their P82 does almost the same job and is about the size of a thumb-nail. You'll need two ESCs as well but that's the way of mixers – you can't clap with one hand……………

Dave M
17 September 2013 at 07:57 #43803
ashley needham
Participant
@ashleyneedham69188
Dave. I have not yet decided on equipment and certainly have that unit in mind. I MAY be using aircraft style brushed controllers as they are cheap and very small..I dont need reverse, but I have heard that this may be a problem with the settimng of the transmitter arms (need to be fully down on som ESC). Time will tell.. Ashley
17 September 2013 at 08:38 #43804
Gareth Jones
Participant
@garethjones79649
Ashley,

I guess the question you have is does the w tail mixer work. The answer is yes, with some reservations. The model in question has limited natural stability in yaw and no rudders so the differential control of the two motors is the only way of steering it. When going in a straight line the motors rotate in opposite directions and drive opposite handed propellers, as is normal practice for twin prop boats. However it is difficult to get the two motors exactly synchronised over the whole throttle range, and one tends to start before the other. The result is that the model tends to wander around a little.

To some degree it is possible to correct for this by putting some rudder trim offset in on the transmitter or slightly offsetting the throttle when settting up the Mtroniks speed controllers. I am still experimenting but the transmitter I am using is an old 2 channel Futaba unit which does not have anything clever like digital trim or travel limiting. The mixer I am using has no means of adjustment so the options for matching the two motors are limited. It may be that because the motors are rotating in different directions their timing is different and so there will always be a difference in performance when they are rotating in opposite directions.

I will send you a PM with a bit more explanation, I think you will find the model quite interesting.

Gareth
17 September 2013 at 09:13 #43805
Trevor Holloway
Participant
@trevorholloway99134
Gareth & Ashley,

That is the same set up as I have in my Lotus Esprit but I have reverse too, the ESCs do not have a set up procedure I can find, so neutral is centre stick.

With a small model (12" x 5&quot and big motors (2 off 500s) speed is not a problem but the small throttle and rudder movements are ie lots of acceleration and oversteering. Ashley knows the trouble I had getting it to run, let alone perform properly.

I may even give it another go at the weekend for some more tweaking.
17 September 2013 at 09:25 #43806
Gareth Jones
Participant
@garethjones79649
Hi Trevor,

It sounds like your Esprit set up is exactly the same as mine which has 2 Graupner Speed 500E motors. I also have reverse and neutral is centre stick. However, for various reasons reversing is not really practical on the model. Selecting reverse is just a means of braking when it is going forward – all will be revealed eventually.

Setting up the speed controllers is just pushing the button in the corner of the Mtroniks ESC when the stick is at neutral. I guess when the ESC has a throttle input which is effectively a summation of two channels via the mixer life is a bit more complicated and I am slso still experimenting with my system to try and optimise its behaviour.

Gareth

Edited By Gareth Jones on 17/09/2013 09:27:19
17 September 2013 at 09:30 #43807
Trevor Holloway
Participant
@trevorholloway99134
Yup reverse is a very efficient brake, however it also seems to dive under water better in reverse than forward !

Still need to fiddle with the hydroplanes for diving in forwards. I also found that with 27Meg there was too much interferance so had to go for 2.4 which does not work underwater (too many comprimises really).

Still a bit of fun and a head turner.
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