ESC problem

[HaigParticipant @haig]

Hi Guys,

I have finally got the internals together in my 1/24 Fairmile D and I was test running the twin motors when one just stopped.
After turning off the circuit and turning it on again the motors worked again with no problems, but then suddenly one will stop.
Upon reset and more running everything is fine but then again suddenly one will stop. There is no pattern but it is a problem.
All the batteries are fully charged. Each circuit has eight NiMH cells x 9AH. The motors are 700BB (12v)

Both electric motor ciruits are independent. The only common thing is that both ESCs are connected through a Y harness to a single receiver outlet so I can use a single stick throttle.
I have attached a copy of the ESC details, and photos of the inside of the boat in my album. The ESCs BEC is disabled.

I am new to ESCs but have been doing RC boats for a long time. I am looking for some expertise to help me through this problem

Regards
Haig

 

Edited By Haig on 14/03/2010 11:16:47

[HaigParticipant @haig]

ESC’s stopping without notice

[ashley needhamParticipant @ashleyneedham69188]

H    Is it the same motor each time?    Ashley

[Dave MilbournParticipant @davemilbourn48782]

Time for a little forensic testing. It’s not ultra-clever – it’s just logical and systematic.

Swap the two ESCs over and see if the suspect speed controller drops out when it’s running the opposite motor. If it does then the fault is the speed controller.

If the other ESC now drops out then the fault is somewhere in the power or drive train on that side of the model. Swap the batteries over and see if the problem “changes sides”. If it does, then it’s the battery pack. If it stays on the same motor then the problem is either that motor or its drive train.

 

If there is truly no pattern (i.e. it can happen to either speed
controller) then I would suggest that the problem is most likely the ESCs. Check for over-heating of the ESCs and the motors.

As you haven’t specified what type of ESC you are using then I can’t say exactly what that fault might be, but they do look a little like those 50A/20A Hong Kong E-Bay Specials with the blue heat-sinks. If so then I will say no more…………..

 

Dave M

 

 

[HaigParticipant @haig]

Dave,

 

The problem truly has no pattern. 

 

The ESC instruction sheet that I have placed in with the photos is what came with the ESCs.  They may very well be the type you describe as they are branded HiMark and are made in China.

 

They were the largest capacity ESCs available in Melbourne when I was looking for ESCs.  They cost around $80 AUD each, and were what was available.  There  was no knowledgeable help from the sales staff.

 

I bought each of the two from a different shop although they are the same brand.   

At the time I asked about disabling the BEC and got no help.

 

I then looked through the ‘net, discovered the Forums and have learnt a lot. 

I have since found out how to do this.It is apparent that the learning is still going on.

 

It was from another forum that I learnt about the servomorph units and have bought 3 from you to rotate the guns.

 

Regards

Haig

Edited By Haig on 14/03/2010 21:42:17

[Dave MilbournParticipant @davemilbourn48782]

Yep – that’s the one. There probably are hundreds out there which work fine, but the comments I’ve had about them don’t bear that out. I reckon that’s the source of the problem and a transplant seems to be the obvious answer – sorry, but there it it.

The MTroniks 15A Viper will handle those motors (avoid the 20A one – it’s a pig), as will the Electronize FR30HX, and there’s another UK brand whose name escapes me for a moment….. ;o)

DM

[HaigParticipant @haig]

Thanks Dave,

I have been offered a couple of options to try, including external suppression of the motors.  If these fail I will be writing to you separately on suggested replacements.

 

Regards

Haig

[HaigParticipant @haig]

The problem was finally isolated and a solution has finally been found.

The 2 x ESCs were running through a Y harness to a single channel.  This was causing the problem.  The use of two separate channels has stopped the cut-outs.

 

The two throttle channels are side by side on the transmitter, and the two sticks are joined and by a removable common bar.

[Ian GardnerParticipant @iangardner62867]

I must say I’m a little worried by this as I am planning just the same set-up on my latest boat. I have two 9.6v 700 motors each with its own 12v  NiMH pack and each with a separate MTroniks 40amp ESC. I was hoping to use a Y lead from Spektrum AR500 rx as I don’t want to get into tank steering. I wonder if I can expect the same sort of problems. I haven’t got to the stage of trying out the system yet but I was advised by a knowledgable chap that this would be OK.

I’ll have to wait and see!

 

Ian

[HaigParticipant @haig]

Ian,

Are you planning to use the BEC from the ESCs. 

I chose to use an independent Rx power supply.  I think the problem is down to signal voltages and low voltage cutouts on the ESCs.  I am not an expert on ESCs, but I have learnt a bit about them now.

 

Haig

 

 

Edited By Haig on 19/04/2010 15:15:37

[Ian GardnerParticipant @iangardner62867]

I was planning to do that, disabling one ESC, but there is plenty of room for a separate Rx supply, although I have enjoyed not having to charge up a separate set of batteries for the Rx in my latest models, but thanks for the info -forewarned and all that!  By the way, nice looking boats.

Ian

[Dave MilbournParticipant @davemilbourn48782]

Ian

Some receivers do produce a very weak signal e.g. the small Futaba 6 channel 40MHz one (I forget the number).  This gremlin is the most likely culprit here, as any fault in the make-up of the Y-lead would probably produce a no-go for one of the ESCs all the time.

I’m on record as being the arch-enemy of BEC when fitted inside speed controllers, but there’s no reason why you shouldn’t use a separate regulator to “tap” a supply for the receiver. Have a look here:

http://www.action-electronics.co.uk/pdfs/P19.pdf

In the case where you are using twin motors with equal packs then I’d advise a separate Rx pack to prevent one of the big ones running down faster than the other.

Dave M

[Ian GardnerParticipant @iangardner62867]

Thanks Dave,

Having spoken to Haig and now with your advice it sounds as though I will save myself grief if I go with a separate RX supply – so be it.

Thanks,

Ian

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