Motors cut out at 85-90% throttle, Bad esc second flight

Hey, I got my machine put together and I have flown it twice. Last flight one of my Motors quit working. Just completely stopped doesn’t beep or anything. Pretty sure it’s a bad ESC. Does anyone know where in the US to get one of these X rotor Pro hv80a V3 RTF esc’s. Only places I have found are China and take a month to get here.

Sorry to hear of your bad luck. Does OpenPPG have any warranty?

Have you tried switching out another esc to that motor and/or vice versa.
This is one reason I want to have quick connectors, for troubleshooting!

Good luck getting back up running.

Cheers, Patrick

I wonder about connectors… if they have interlocks then I’m good, just wouldn’t want anything coming apart.

I bet it isn’t the ESC it’s probably a wire that came loose. I’ve never seen one of these ESC fail, and they don’t usually fail like that but it could be the case. Let us know when you do some more testing.

I checked all the wires again today. Then I swapped the ESC s and the motor started working. I think that confirms that the ESC is the problem.

That proves the motor is good. Did you put the suspect ESC on a different motor to see if the problem followed the ESC?

Sorry I left that detail out. Yes I did connect the bad ESC to another motor and I got the same result.

Ok, I replace the bad esc and all 4 motors work. Now I have another problem. Everything works fine up to 85-90% throttle. If I ease it past 85-90% I feel one motor dropping out and if I go full throttle all 4 motors quit and start beeping. The throttle still says armed but motors will not turn after I go full throttle and they quit. If I cycle the main power switch off and back on it will work again. Before this happened it stuck at roughly 1/2 throttle until I shut off the main switch. Did I somehow mess up the programming? It ran perfect in my initial 2 flights until the esc went bad. After running it for a couple minutes at 60-70% throttle the esc’s are getting warm. I can touch them but wouldn’t want to keep my hand on it. Thanks for the help.

@customair CAREFUL! That’s what happened to me and resulted in a downwind engine out low to the ground.

In my case, it was the power switch, but ultimately what is probably happening here is voltage sag in the power distribution. This causes the ESCs to brown out. In my case everything worked well for the first 3 flights and then there was so much loss (as heat) in the power switch that it melted. You are likely having a lot of loss as well, which means a somewhere in your power distribution is likely getting really hot!

Do a tear down, find the hot spot and fix it. Don’t try to fly it until you find the problem.

That brings up my question I brought up in another thread. Is anyone sure that the power switch being used is rated for 300 Amps? I’d like to see a datasheet for that switch.

Davek79 Thanks for the help. I found a bad connection at the battery. Fixed it and it seems to be better. I will do more testing tomorrow before I fly. My switch seems to be fairly cool 90-100 deg.

This is all great info - I know I will be doing a lot of ground testing before I take her up.
Cheers, Patrick

I have experienced almost identical symptoms. I believe it’s ESC programming related. Will be doing more tinkering this week.

I did more testing yesterday. It is still cutting out at 85-90% throttle. I bypassed the master switch and it did the exact same thing so it is not the switch. I also checked the voltage and it never dropped below 44-45v. All 4 motors drop out at the same time if I go full throttle. I agree, I think it’s esc programming related. Is there a process to learn the throttle? It seems to me that the throttle position is not set correctly.

Here is a thread where we talked about programming the throttle range.

Mine is working good so I decided not to mess with it. I’m a bit concerned that @Lukas is having similar problems because he’s the one that found the instructions on how to do it. However, it is similar to any other RC ESC programming. We figured out that you can arm the throttle controller using power from a USB plugged into the bottom of the controller. Then while holding the throttle on full turn on the power to the rest of the system. This gets you into the programming mode. Follow the instructions in the link for the rest.

Ok, I have reset the throttle, changed the timing to high, and resoldered all of the fittings. It is still cutting out at 85-90% throttle. I bypassed the master switch and it did the exact same thing so it is not the switch. I also checked the voltage and it never dropped below 44-45v. All 4 motors drop out at the same time if I go full throttle. Could it be the controller that the throttle is plugged into? That is the next thing that makes any sense to me.

This may or may not be related to the cutout at high throttle, but maybe it is related to the ESC being damaged. In the RC world, it is somewhat known that long power leads to the esc increases inductance, which leads to higher voltage spikes on the ESC since the power draw isn’t continuous (PWM). This is the reason why the ESC includes very long motor/phase wires and short power supply wires, as the length on the wires for the motor side isn’t as critical.
Here is a very detailed RC groups thread addressing the issue

To be on the safe side, I added some 470uf, 100V caps to each of the motor power leads near the start of their respective connectors to my power distribution mess. They are somewhat separated from the ESC rather than being close to it for reasons described in the rcgroups thread.

Here is an image showing what I did.

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Hi – nice Caps – what is this switch for going to your main power switch?
Thx, Patrick

Pre-charge pushbutton + resistor to avoid the arcing on the main switch as some people mentioned they were having issues with that. Was planning on making a separate post later with some details on the mods I did, part numbers, etc if you’re interested in more details.

That all looks like a good idea but I see that others are having success with the standard setup. I feel like I have another problem causing the cut out. I would think if it was a problem with the length of the wire between the battery and the esc then the longest one would cut out and the one closest to the battery would keep working. Has anyone had the same problem? How did you fix it? My leads going to the esc’s are as short as they can be.