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[unbuiltnautilus]

Just a heads up for anyone who has used the great Quicrun 880 twin speed control. Despite being rated at 14.4v and 80 amps constant current drain, being designed for operating TWO 550 type performance motors, they do not like the big MFA Torpedo 800/850 series motors.


I have had two (possibly three ) users having the following problem. Full power forwards and reverse, then after ten to twenty seconds dropping down to half speed, then cutting out completely. One I had on the bench in front of me. By a long process of elimination, testing the supply voltage under load, trying a different chemistry battery, reprogramming low voltage protection, replacing the motor, then replacing the speed control with a new Quicrun 880, problem persisted.
I then fitted a 15 Amp Mtronics Viper High Voltage 12/24v speed control, problem solved.


So, not being an electronic guru, my mind floated back to those Tamiya mechanical speed controls of the eighties, using 'back EMF' to provide a breaking action for the car as you throttled from forward to reverse. So my simple mind has some sort of dynamo effect freaking out the Quicruns.


Any further thoughts on the subject?

[J.beazley]

Happy to agree with this.
They dont like torpedo 800's on a 12v sla battery had a pair running in my hms mersey for each motor on seperate channels, 1 motor pulls a little more amps than the other.
Sadly full ahead to full astern a ESC decided it didnt like it and the black smoke effect took over, luckily i wasnt far out when it happened as the smell is horrendous when lifting the superstructure off to stop the smelting process, the stall current recorded on my tx from the boat was a healthy 26amps, when it was tested on the bench it was higher so no idea what went wrong with it.


Plus side is ive moved onto Radiolink esc's and they seem to be holding upto the job, so far no meltdowns to report.


Jay

[HMS Invisible]

Just a heads up for anyone who has used the great Quicrun 880 twin speed control. Despite being rated at 14.4v and 80 amps constant current drain, being designed for operating TWO 550 type performance motors, they do not like the big MFA Torpedo 800/850 series motors.


I have had two (possibly three ) users having the following problem. Full power forwards and reverse, then after ten to twenty seconds dropping down to half speed, then cutting out completely. One I had on the bench in front of me. By a long process of elimination, testing the supply voltage under load, trying a different chemistry battery, reprogramming low voltage protection, replacing the motor, then replacing the speed control with a new Quicrun 880, problem persisted.
I then fitted a 15 Amp Mtronics Viper High Voltage 12/24v speed control, problem solved.


So, not being an electronic guru, my mind floated back to those Tamiya mechanical speed controls of the eighties, using 'back EMF' to provide a breaking action for the car as you throttled from forward to reverse. So my simple mind has some sort of dynamo effect freaking out the Quicruns.


Any further thoughts on the subject?

I'm looking at the manufacturer spec.
I'm seeing clip on fan kits for these.
No fan, shared small heating for 2 escs, 16 awg silicone insulated cable so I expect fets are only 0.003 ohm.
It looks like a push-on heating with thick rubber insulation pads that don't conduct.
I think you are getting a thermal cutout at 8kHz pwm.Try 2kHz or 1kHz and a fan kit.

 You could loan a pair to me for closer inspection. I've shelled enough this week on Chinese escs because they'll sort problems of other folks at a tenth of their spend.



 

[Fastfaz]

Has anyone had this problem on a boat using an MFA 800 single screw and a Quickrun ESC? I am planning to use this set up in a coaster with a 60mm 4 blade prop later in the year.
       Regards, Pete.

[HMS Invisible]

There's no revelation here, Peter.  You'll be OK.
Marketing clickbait has been called out by a shopkeeper.*
This esc model really needs forced cooling.

I've copied and pasted the important disclaimer hidden away in a description page that you have to hunt for.

KV Rating/T Count for single motor use, double when using two motors.

Brushed Motor Limit with 2S LiPo/6S NiMH: =12T or RPM<30000@7.4V (540/550 size motors)
Brushed Motor Limit with 3S LiPo/9S NiMH: =18T or RPM<20000@7.4V (540/550 size motors)
Brushed Motor Limit with 4S LiPo/12S NiMH: =24T or RPM<15000@7.4V (540/550 size motors)

 

When Driving 2 Motors Simultaneously the Turns/T Count of the Motor Must Be Increased Accordingly.

* or manager

[Papa Joe]

Ran into a quirky issue with the Quicrun 880 twin speed control and big MFA Torpedo 800/850 motors.Full power, then dropping to half speed and cutting out after 10-20 seconds. Ended up switching to a 15 Amp Mtronics Viper High Voltage speed control, problem solved.

[HMS Invisible]

Ran into a quirky issue with the Quicrun 880 twin speed control and big MFA Torpedo 800/850 motors.Full power, then dropping to half speed and cutting out after 10-20 seconds. Ended up switching to a 15 Amp Mtronics Viper High Voltage speed control, problem solved.

There's a huge gulf in load current between an 800 and an 850 motor and the prop & operating voltage matters too.
The best way to present the information is current or power readings or rpm & esc temperature readings.
At least the thermal cutout is effective and a current overload doesn't melt the silicon of the drive transistors.

You can fit a cooling fan, change to a lower frequency for like-for-like comparison, change the thermal cutout threshold.

[unbuiltnautilus]

There's a huge gulf in load current between an 800 and an 850 motor and the prop & operating voltage matters too.
The best way to present the information is current or power readings or rpm & esc temperature readings.
At least the thermal cutout is effective and a current overload doesn't melt the silicon of the drive transistors.

You can fit a cooling fan, change to a lower frequency for like-for-like comparison, change the thermal cutout threshold.

My test was on the bench with a Torpedo 800, which is the lower current motor of the pair, and it tripped.
Okay, cooling fan is supplied with the unit, but this fault manifested itself within thirty seconds of start up. No time for the unit to get hot, let alone cooled again by a fan.
I will run a test tomorrow on a lower PWM setting, see what reveals itself.

[HMS Invisible]

My test was on the bench with a Torpedo 800, which is the lower current motor of the pair, and it tripped.
Okay, cooling fan is supplied with the unit, but this fault manifested itself within thirty seconds of start up. No time for the unit to get hot, let alone cooled again by a fan.
I will run a test tomorrow on a lower PWM setting, see what reveals itself.

  I didn't think for a moment your tests were out of the water. This means you have a flywheel without an external braking effect. You will be operating with running mode set to "forward/reverse," which will disable drag brake, but you will still have the crawler brake at the centre. You have item 3 (cutoff voltage) disabled too.
 Out of the water operation together with less than optimal 'crawler' settings or the punch throttle looks like the culprit which, very broadly, fits your "back EMF" description. So settings of parameters 4,7, and 8 may have an influence
 I still think the actual tripped mechanism is a temperature cutout because of the time to trip, which is faster than you thought, and by the two step cut-out at 90C and 105C thresholds.
  I further suggest increase 3. neutral range to wider so there is less chance you unknowingly sit motionless at ~3% throttle if you don't monitor the status LED. A 1kHz or 2kHz pwm whine will flag this possibility too.

[unbuiltnautilus]

Correct about the settings. The adjusted ones are 1, forward / reverse, 2, NiMh, 3, Disabled, 6, 100% Reverse, 12, Start mode/punch, Level 2 (sometimes), and other than that, factory settings. However I have tried 13, PWM Frequency at 1K and 2K. Off load all was fine, with a sacrificial paintbrush handle against the motor shaft for about fifteen seconds it demonstrated the two stage shutdown observed on the higher PWM Frequency setting. Turning the unit off for thirty seconds allowed it to reset.


So the question is, does the answer lay in those mysterious crawler settings, or is this unit just not suited to the really big motors?

[HMS Invisible]

Correct about the settings. The adjusted ones are 1, forward / reverse, 2, NiMh, 3, Disabled, 6, 100% Reverse, 12, Start mode/punch, Level 2 (sometimes), and other than that, factory settings. However I have tried 13, PWM Frequency at 1K and 2K. Off load all was fine, with a sacrificial paintbrush handle against the motor shaft for about fifteen seconds it demonstrated the two stage shutdown observed on the higher PWM Frequency setting. Turning the unit off for thirty seconds allowed it to reset.


So the question is, does the answer lay in those mysterious crawler settings, or is this unit just not suited to the really big motors?

 If the fan is fitted it won't take thirty seconds to reset. And that is definitely a thermal cutout with the recovery time gap.
 Are you saying the slower frequency has stopped or reduced the problem on the bench?
If so, it does not surprise me. It would be encouraging too. The optimum settings for boat operation would differ from a crawler because water will do the braking. Without water, the pulsed FET braking is heating the esc up.
 Without trying this dual esc model or seeing what you are doing I am confident it is capable of running the 800 & 850 without issue with the fan attached. However, I forsee reports like these are going to become repetitive.
 To me, the issue is as much to do with one 16awg battery cable & one small heatsink for two motors.

[Martin (Admin)]

 
Lots on Utube:

https://youtu.be/7OeL-QiIYNU?si=B4IKbij-M_VEfbUs
 
https://youtu.be/K6tyCilm_UM?si=qdb0MlsKWzUAmb72
 
https://youtu.be/0jOW4sWTzHM?si=xOTVzRnKYk3AhGCJ

Fake one!
https://youtu.be/QKCzj6AcvhI?si=Lw0maFDlLMXP1yH3

 

[unbuiltnautilus]

Update. Spent 20 minutes on Saturday morning waiting for a customers Envoy tug to drift back in to the bank following a test. This time, 60mm prop, MFA 540/1 on a 2.5:1 reduction gearbox and a 12v gel battery supply. Worked in the water for about thirty seconds before tripping out while heading away from the bank. Once recovered and out of the water it demonstrated the same trip out within about twenty seconds. By the time I got it back to the bench, about an hour, it refused to trip out while off load. I also think it tripped out the BEC supply to the Rx but cannot confirm that.
Time to give the importers a ring I think..

[unbuiltnautilus]

Just a heads up, the lower frequency settings didn't seem to solve the problem, and for clarification, the 880 is a single speed control with twin output cables rather than a twin speed control 'glued' together!

[HMS Invisible]

Update. Spent 20 minutes on Saturday morning waiting for a customers Envoy tug to drift back in to the bank following a test. This time, 60mm prop, MFA 540/1 on a 2.5:1 reduction gearbox and a 12v gel battery supply. Worked in the water for about thirty seconds before tripping out while heading away from the bank. Once recovered and out of the water it demonstrated the same trip out within about twenty seconds. By the time I got it back to the bench, about an hour, it refused to trip out while off load. I also think it tripped out the BEC supply to the Rx but cannot confirm that.
Time to give the importers a ring I think..

That's very useful info but you don't say if you the fan fitted.
You are describing a thermal cutout.

I know the format of the 880. Like I said in other terms, the heatsink doesn't dissipate the generated losses. Current from two overpropped motors run through a 16awg shared supply cable. Silicone doesn't conduct cable I²R loss well. A lot goes back into the esc so it needs cooling.

This is what I don't understand.
Re 540/1 on 2.5:1 reduction is no more torque than a 555 but I had thought you knew that!
555 on 2.5:1 or Re540/1 on 6:1 reduction is a starting point.

[unbuiltnautilus]

The fan was indeed fitted.
My extensive knowledge sometimes doesn't stretch to the infinite on motor specs, however I personally would have fitted a 6:1 but I only have the toys handed to me to play with!

[HMS Invisible]

If nobody leaps in before me tomorrow morning, I'll use published MFA Como data* on the RE 540/1  and the 55 turn version of the Mabuchi 555 to make a meaningful graphical comparison of the two motors. I'll do it on a new thread.
 Anyone can use the same method to halt the random guess game, to stop wasting money on the wrong motors time after time.
* Last measured by me, decades ago, and found to be very accurate.

[Circlip]

Was going to comment on the correct term for 'Braking' effect but 'Breaking' seems more apt.         


  Regards  Ian.

[unbuiltnautilus]

Like a dog with a bone I have solved it!


This morning I did a high current test with one of those Johnson motors that the ill informed on here don't like.. Using a 7.4v LiPo with an 8" aircraft prop on, I ran it for about six minutes and it refused to trip, most annoying.

I then spoke to the importers and asked if they had encountered any issues with these speed controls. Turns out the only return they had had since November had been sent back by me.. cursed I am.

Next test after it had been bothering me for the better part of the day, involved a Torpedo 800 with a 10x6in wooden aircraft prop on it, using a 12v gel battery. It tripped after thirty seconds. So, fine on the lower voltage, but not happy on the higher one?

Nope, after a bit of brainstorming and checking the programming parameters, and trying options to see what happens. It turns out that line 2 of the programming which relates to the choice between LiPo battery and NiMh battery has been transposed, so what I thought was a NiMh setting with no low voltage protection, was in fact set to LiPo, and as the gel batteries voltage rapidly sagged to eleven and a few bits volts the LiPo (NiMh!!) setting tripped out the speed control to protect the LiPo (gel battery!!) from over discharging.

I have all but confirmed this by testing a few variable options, and getting the same results. So once I have tested another four that were returned by a customer, I shall re-install, again, the QR880 in the tug and take it out for a test sail.

So, only goes to prove, sometimes when problem solving, we all have blinkers on!

Post script, I have a distant memory of a batch of Quicrun 860s from about three years ago, doing exactly the same thing..

[unbuiltnautilus]

Following a fifteen minute bath test last night, I can confirm that everything is now running fine. So just to confirm, the  current batch of Quicrun 880s do seem to have an issue with line 2 of the programming, where LiPo should read NiMh and NiMh should read liPo. So just be careful if you are running Lipo batteries, maybe just carry out your own tests for peace of mind before over flattening a LiPo pack!