4 EDF Model Vulcan - motor/speed controller problems

[TonyS]

I've been trying to build a 4 EDF model Vulcan for the best part of 5 years now, maybe longer. It took shape quickly but came to a screeching halt when I got to wiring it up and has sat on my workbench ever since. Every so often I pluck up enough enthusiasm to 'give it another go' and so, here I am.

Basically the problem is this. No matter how I wire the system I can only ever get two fans to work.

The set up was meant to build in some redundancy, one battery powers the two inboard fans, the other the two outboard fans. I did this such that if one battery gave up the model would still have two motors.

Anyway, the set-up is as follows:

The four speed controllers have four plugs each with a positive, negative and data wire. I have disconnected the orange data from three of these. So the four plugs then go into a 4 in 1 connector which then connects to the throttle port in the receiver.

The power cables from the outboard EDF speed controllers (red and black) connect into a 2 into 1 and then into one battery, the inboards do the same into the other battery.

I switch on my Tx (a Spectrum DX7) and then connect the two batteries. The two inboard motors then bleep and respond to throttle inputs from the Tx. The outboards EDFs are dead.

 

I've just tried changing the battery set-up so that in place of the 2x 4S batteries I have 2x 2S batteries in series and all 4 of the  motors then connect together. I did this in case the problem was connecting first one battery (which then primed 2 speed controllers) then connecting a second but at this stage the second pair of speed controllers wouldn't be recognised. Same outcome - 2 EDFs working, two EDFs dead.

 

If I mess around I can get the 2 outboard EDFs to work and then the two inboard EDFs are dead.

 

If anyone can provide any pointers as to what I could try next I'd be immensely grateful. I did by the way post about this (about 4 or 5 years ago I think though I've lost track of time).

 

Thanks

 

Edited December 31, 2022 by TonyS
correction

[Martin Gay]

Tony,

My immediate thought is that the speed controllers need data/signal and negative wire from the rx to function, not just the data/signal.

A circuit diagram of how you have it wired up would be useful. Even a photo of a hand drawn one would work.

Martin.

[Martin Gay]

This might help if you have not already seen it:

Microsoft Word - How to wire up a twin Brushless aircraft rev 2.doc (4-max.co.uk)

[Andy J]

Tony, could you make a quick sketch of your electrical connections to the speed controllers and motors?

[Philip Lewis 3]

56 minutes ago, TonyS said:

I have disconnected the orange data from three of these

I assume this is a mis type? It's the positive power you need to disconect from three of the ESC's

Edited December 31, 2022 by Philip Lewis 3
Spelling

[Martin McIntosh]

You should have disconnected the positive (red) from three of the four ESC`s, not the signal which they need, otherwise they will have no input and you will be powering the Rx four times over which is a no-no. The ESC leads need to go into a four into one connector which then goes to the throttle channel.

[john davidson 1]

Wiring a twin motor is one thing, wiring with twin batteries  is some thing else. I made a Twin Mustang some years ago with a battery in each fuselage to balance ,and had I think the same weird results until I programmed one ESC as a slave to the throttle channel. There was a very slight delay winding up the second motor , not noticeable in the air  Four could be done this way as long as there are spare channels

Edited December 31, 2022 by john davidson 1
addition

[Andy J]

Tony, this diagram may help.

[TonyS]

So, here goes...

The, ahem, wiring diagram

[TonyS]

51 minutes ago, Philip Lewis 3 said:

I assume this is a mis type? It's the positive power you need to disconect from three of the ESC's

Yes, apologies, the power is what's disconnected.

[TonyS]

56 minutes ago, Philip Lewis 3 said:

I assume this is a mis type? It's the positive power you need to disconect from three of the ESC's

Yes, a mistype. Oops!

[Andy J]

For a starter for 10, the -ve's of Bat 1 & Bat 2 need to be interconnected to provide a common ground to all 4 ESC's.

[Andy J]

Next query is how did you wire up the BEC supply to the RX?

[TonyS]

52 minutes ago, Martin McIntosh said:

 

 

2 minutes ago, Andy Joyce said:

For a starter for 10, the -ve's of Bat 1 & Bat 2 need to be interconnected to provide a common ground to all 4 ESC's.

That may well be the issue........ The negatives aren't interconnected!

 

[TonyS]

2 minutes ago, Andy Joyce said:

Next query is how did you wire up the BEC supply to the RX?

There's no sep. BEC supply - 

[Andy J]

So how is the Rx powered?

 

[Frank Skilbeck]

As shown the batteries should all be grounded together via the negative leads to the receiver, but it's worth checking.

 

It may well be that the throttle signal is too weak to power 4 ESCs, this is driven from the chip on the receiver, although the current is very small it could be that it is insufficient top drive all 4 ESCs, if you plug the ESC's in separately do they work? I know that a friend had a similar problem with some electric retracts they wouldn't work unless he was using the lead supplied with them which had an inbuilt signal amplifier. If you search servo signal boosters you'll see several inline signal boosters are available. The other option would be to use separate channels on your Rx, but you may not have enough channels to do that.

 

[Philip Lewis 3]

8 minutes ago, TonyS said:

That may well be the issue........ The negatives aren't interconnected!

I think that is the likely issue, you need a common ground to all.

[TonyS]

5 minutes ago, Frank Skilbeck said:

As shown the batteries should all be grounded together via the negative leads to the receiver, but it's worth checking.

 

It may well be that the throttle signal is too weak to power 4 ESCs, this is driven from the chip on the receiver, although the current is very small it could be that it is insufficient top drive all 4 ESCs, if you plug the ESC's in separately do they work? I know that a friend had a similar problem with some electric retracts they wouldn't work unless he was using the lead supplied with them which had an inbuilt signal amplifier. If you search servo signal boosters you'll see several inline signal boosters are available. The other option would be to use separate channels on your Rx, but you may not have enough channels to do that.

 

Thanks Frank,

I have put a signal booster in the circuit between the 4 in 1 and the Rx. The retracts work well - and they are quite chunky, so I'd be surprised if there was insufficient signal to power 4 ESCs but then, what do I know....

I've just connected all the negative leads from the batteries however I still only get the two inboard fans powering up.

I'm using a Spectrum AR500 Rx which is small but there are spare channels. I'm not sure how to slave a separate channel to the throttle though?

 

[TonyS]

12 minutes ago, Andy Joyce said:

So how is the Rx powered?

 

Andy, it's via the power wire from the ESC

[TonyS]

8 minutes ago, Philip Lewis 3 said:

I think that is the likely issue, you need a common ground to all.

So I've just connected the negatives and still nothing?

 

[Paul De Tourtoulon]

Silly but have you tried one by one on your RX, it could be a program problem on your controllers.

[TonyS]

Latest attempt.....

 

Edited December 31, 2022 by TonyS
sent wrong pic!

[TonyS]

2 minutes ago, Paul De Tourtoulon said:

Silly but have you tried one by one on your RX, it could be a program problem on your controllers.

No such thing as silly at this stage. Got to be worth a try. I have had the outward EDFs working but who knows....

[TonyS]

51 minutes ago, Andy Joyce said:

Tony, this diagram may help.

On this diagram is it right that only the white data wire is connected from each speed controller?