ESCs Stopping without notice
 

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 work again with no problems, but then suddenly one will stop.
Upon reset and more running everything is fine but then 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 a photo of the inside of the boat. 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

RE: ESCs Stopping without notice
 

Just make sure you are using the 50 amp rating and ensure adequate ventilation.

If you are running in water then you have triggered a safety cutout.Since there is no indication in this,you are left in the dark.Force cooling or reduced battery voltage will confirm if that is the case.

It would also be advisable to measure your current drain which is caused by friction or oversized props.

RE: ESCs Stopping without notice
 

There is water cooling on the motors, The pros are two bladed 38mm dia. The fuses are currently 15Amp. The ESCs are rated for 50Amp but should not get there

I was testing on the bench and there was no load, no overheating. The system re-starts immediately if you turn off the power and radio receiver and re-start.
The boat has not been in the water.

RE: ESCs Stopping without notice
 

It cannot therefore be a safety thermal cutout.It is either some kind of voltage or bec cutout so I'll leave it up to those who actually use these escs and know the other quirks.

It may help them if:
[ul][*] you say what you mean by turning off the circuit.[*] say at what position the esc switches.[*] confirm the receiver pack is fully charged[*] observe what happens with bec power from an esc.[*] observe what happens with the working esc disconnected[/ul]

best of luck!

RE: ESCs Stopping without notice
 

Try installing the suppresors on the motors(3). Arcing can play havoc with some radios, not so much with FM as with the AM though. But it can still happen. Also, try moving the antenna from being curled up in the boat. Just as a test. And fully extend the transmitter antenna for your testing. Does the same motor stop each time?

In-d-boat

RE: ESCs Stopping without notice
 

That is a valid point which I ignored on the mention of one esc of two on a Y-lead stops and disarms.

I don't see any suppressors in the picture.Make sure there is an externally mounted suppressor from motor + to motor - and ignore what is written about these motors being internally suppressed.

Despite only one esc cutting out I think that is a likely scenario.

RE: ESCs Stopping without notice
 

Is the system running on an RX battery AND BECs?
Its normal practice to use either, but not both. If the red signal wire of the ESCs are disconnected by winkling the red wire out and taping back, the ESCs will each draw control power from their respective power battery.
I would consider putting a twist into the motor leads to reduce transmitted interference, in addition to all the previous suggestions.

RE: ESCs Stopping without notice
 

I tried to run a pair of the original Proboat blue boxes, and they seemed to run
at a frequency that at 50% throttle, one would always cut out, then as i reduced
throttle, the stalled ESC would come back to life. Didn't matter how I suppressed them.
And, the motors I was running at the time, did not draw more than 2amps stalled...

I switched them out for a pair of different ESC, and use the blue boxes as back up
ESC in my pond side tool box, but never use them as a pair... [&:]

RE: ESCs Stopping without notice
 

To All that have helped.

The BEC is disabled in both ESCs.

I tested the current drain on the motors and at no load 'free running' out of water only 1.3 amps was being indicated on each. The boat has not been in the water. There is no overheating at all.

I have not added suppressors, as the Graupner 700 BBs were supposed to be internally suppressed, according to a previous forum item, and it also said so on the motor instructions. I can add these, but there was no jittering, all runs smooth until one of them stops - either one.

Umi - I think that your scenario closely resembles mine although mine don't come back to life. You need to switch everything off and then start again. It then works fine until...

Regards

RE: ESCs Stopping without notice
 

So one esc is disarming? That would be a starting point but I stand by what I said on fitting an external suppressor.

Out of my own interest,does this esc auto-set the neutral at power-up or is it a fixed neutral?

RE: ESCs Stopping without notice
 

stmjxxi,

Only one ESC stops at a time. It can be either one. No pattern except that one will stop within a couple on minutes.

The transmitter stick I am currently using has a ratchet and is not one that comes back to neutral. This setup was for testing. Where ever the stick sits when I turn on the transmitter and receiver becomes the neutral point. Max forward forward and reverse are then based on the travel to each limit. This is autoset by each ESC.

I noticed during one test run that the ESCs lost their neutral point relative to each other and one would be going forward when the other was at neutral, and at one time one was going in reverse compared to the other forward. On the main stick I would hope that the neutral zone is a bit larger.

Anyway this is a different issue from the main problem. I will fit suppressors to each motor and give the system another try, but based on what I am reading from Umi, this may not solve the problem.

Regards

RE: ESCs Stopping without notice
 

That is a definite description of disarming.

As far as I know,only a power down on the receiver supply line will cause it.
Possibly a negative going transient has happened and temporary use of one of the esc becs might clear that up.

The motors have two of the three internal suppressors already fitted.

RE: ESCs Stopping without notice
 

I can try as you suggest, after I add the main terminal to terminal suppressors. I have some polyester ones.

It is peculiar that this can have happened to both ESCs and what can prevent it happening again.

Doesn't the ESC memory reset when the power supply and radio signal is totally disconnected for a few minutes.

Thanks for the tips so far. My first time with ESCs and I have ended up with a curly one.

RE: ESCs Stopping without notice
 

I have had a similar problem before when using 2 ESC's. It is recommended to disconnect the + of one of the ESC's if they are powered by BEC. I have noticed this in different specs on radios and esc's. Might be worth a try.

RE: ESCs Stopping without notice
 

Why not just run both motors from one ESC? And be done with it. Just don't stall the motors(unlikely), and you should be ok. Stall on that motor is 43 amps. I'm starting a Baltimore Class heavy cruiser soon. It has four props, and I'm going to use 2 speed controls rather than four. One speed control for each pair of motors.

In-d-boat

RE: ESCs Stopping without notice
 

Another thing to try, run the setup for each ESC each time you turn on the boat.

Seems like that helped at one time also...

RE: ESCs Stopping without notice
 

Latest update, and thanks for all the help and ideas so far,

I haven't had time to put the suppressors on (but will do so), but thought I would try a few ideas out.

On one circuit (Port side) with one ESC, the motor ran for at least 5 minutes before I stopped it. Then I turned off the circuit and switched on the Starboard side. It ran similarly. The only thing that got warm were the tubes of the propeller shafts which are fully greased. Both tubes were similar

Then I started again with both circuits on. They ran for nearly two minutes before the starboard stopped. On the next attempt the Port side stopped, this time about a minute running time.

So one thing is clear. They don't like running together. The next is suppression and more testing.

Another thing I could do with some help with.

I have a new battery charger Swallow AC/DC EQ charger, that asks for the following in NiMH mode (I am charging each battery comprising of 8 D cells = 9.6V 9A/h)
*charge current (I am intending 0.9amp).
*discharge current (open to suggestions)
*minimum discharge voltage (open to suggestions)
*charge to discharge vs discharge to charge [cycle] (I think D to C)
*delta-peak-volt = 0 mV/cell (charge termination point)

The unit must sense how many cells there are because you cannot set the battery capacity for NiMH orNiCd, Only for Lithuim-Ion, Li-Po, or LIFePO4. The instructions are not helpful for the info requested above as there may be too many battery types to consider?

I am mainly used to lead acid gel cells, and nicads for radios so this is a bit new. I searched the net and found a data sheet for a similar D cell but not enough info. The battery charger does not give examples of settings for these.

RE: ESCs Stopping without notice
 

Did you clear this notion up?

RE: ESCs Stopping without notice
 

Hi stmjxxi,

Short answer is not yet.
I need to take the ESCs and motors out of the boat to put the centre BEC power wires back (currently folded up and taped) and also add the external suppressors.

"Power down on the receiver line" suggests that the receiver battery was down or low, or the receiver power switch turned off before the switch on the ESCs.
Is my understanding correct. At first I wasn't sure what you were getting at, but the solution is straight forward.

Do you think I should do this procedure on both ESCS, as either or both could have been affected.

RE: ESCs Stopping without notice
 

So the esc switches are in the ON postion and their circuitry get their juice from the D cells.Getting somewhere now.

The escs are disarming because the internal circuitry detects low voltage.
Suppress the motors.
It's up to you whether you are willing to try reconnecting centre pins and keeping switches OFFor using a different grade of battery.
The D cells can't maintain enough voltage with a 700bb and no suppressor.

RE: ESCs Stopping without notice
 

Hi Stmjxxi,

I will add the suppressors tonight (no question), but I flattened the batteries last night with my testing and haven't recharged them pending some helpful info per my previous post with regards to the battery charging.

The main power each of the motors is from 8 x D cells = 9.6V. The power to the ESC's is via a separate receiver battery (4 AA cells ~ 4.8v) so that low main batteries don't cause my radio to stop. I will do as you suggest and run via BEC to correct the transient earthing possibility.

I am trying the two x 8D cell NiMH battery systems as they have a better power to weight ratio than the usual 6V x 7.2 A/H gel batteries that I normally use in the other boats. The 9 A/H rating was also a plus.

Question. Why does the disarming only happen when the two circuits are in operation. Do you think that the receiver power supply - when split via Y harness may be the problem.

Question
I am not sure if I understand this correctly.
What will occur if I connect the BEC wire and keep the ESC switch off It's up to you whether you are willing to try reconnecting centre pins and keeping switches OFF. Power is connected from the main battery and from the receiver. If the switch is off then I assume the power may come via the main battery. Is that correct. Will the radio signal still come through to the ESC.

RE: ESCs Stopping without notice
 

If you have that center red wire removed from the plug, then the ESC are still getting their
power from the main batteries.

Removing that center wire, OR, leaving the ESC switch OFF, just prevents the BEC from supplying
power to the receiver. If you are running the main batteries down, then the ESC may still be
executing a low power reset when the main battery power drops.

The signal and its baseline come through the white/yellow wire, and the ground(black/brown).

RE: ESCs Stopping without notice
 

Don't bother because you have been doing that all along and that is partly what is causing the problem.I was trying to get you to eliminate the possibility of a bad connection/bad cell in the receiver line but, all along,you had used the becs for the escs.
That was the reason I asked what position you had the esc switches in.

Umi has just stated the switch just isolates the power to receiver but I think it may isolate either the input or output right at the bec regulator.That would allow you to power the esc 5 volt circuit from the receiver pack and avoid the low voltage cut out.

Best just to forget that and concentrate on the NIMH D batteries.

Fraid the likely problem is the NIMH D battery is too low power for 700bb even although the capacity is higher than the gel battery.
If,as you say,there are two separate circuits and you have not joined the NIMH batteries or escs at any other point other than the Y-lead then I don't think it actually has relevance.
Forget about that completely.
I was not on the same wavelength as you.I tried to find out which battery supplied esc internal circuitry(and the voltage failsafe) and you said you disabled the becs.

RE: ESCs Stopping without notice
 

A while ago (21Oct2007) I asked this forum how to disable BEC in ESCs. The Thread is 6518113. Even Umi offered some advice.
I did as recommended and disconnected the red wire. I am still learning a lot more about them thanks to all the comments.

Question.
Why does either circuit work without problem if only one is in operation, yet has random dropouts "disarming", if both circuits are put into operation?

If it is down to the D cells, then the ESC should drop out even if only one circuit is working.

In last night's testing I ran each circuit separately - right down to stopping (ie low battery) but neither ESC cut out.

The ESC's only work with the ESC switch turned on.

There is a copy of the ESC's instruction sheet with the original thread. Worth a review.

I thought that the NiMH batteries were the best for the purpose (apart from the LiPO), is this not the case?


Is there a better way to disable the BEC? or not have the main batteries to power the ESC circuitry


I worked too late tonight to have time on the boat. Suppressors are still top of the list.

RE: ESCs Stopping without notice
 

Yup,I read through the instructions.
All I can add is that ,if it was dropped on my workbench,I could have sorted it out while being on the stopclock.
For now,I would ignore the fact that they individually worked ok.

That depends on where the switch is connected and what bec component is used.There are ways of finding out but have you got the inclinationright now?