Granite Uodated: Cogging at mid throttle/2800kv swap

[blackgoat04]

nevermind...drive shaft is out. derp

 

[bicketybam]

is it possible that having diff fluid that's too thin might play a role in this high motor heat, cogging, brakes not working on the hill? it's so thin the other tire isn't spinning backwards when I rotate the other side. watch

https://www.dropbox.com/s/fq71aq0mm5x9oxn/20190212_212107.mp4?dl=0

Have you opened the diffs to see whats in there?

 

[blackgoat04]

Have you opened the diffs to see whats in there?

yes. no. not today. I just tore it down on Sunday and cleaned bearings, changed diff fluids, grease etc.... but I did have the diffs in my hand they sound great. did you hear the one in the video?? quiet as can be

 

[DoNoHarm]

Correct on the MOSFETS, it's them causing your issues. In general, more mosfets= the more amps an esc can handle. Only problem is, once one drops the esc is toast. The cogging symbolizes a failing FET. Some esc's have a parallel wiring so the esc only gets shot in the foot when one FET goes out, but that's only reserved for brands like castle and tekin and on their latest esc's. I recommend the max10sct as well. A binding drivetrain ain't gonna create a cog halfway through the throttle range, that's gotta be electrical, unless the OP isn't describing the issue correctly.

 

[crankestein]

Some brushless motors start to do the excessive cogging when they are somewhat damaged and about to die. If there is some loss of power w it then the motor is not thay healthy, possibly will run backwards at times. (on some occasions)

 

[DoNoHarm]

Some brushless motors start to do the excessive cogging when they are somewhat damaged and about to die. If there is some loss of power w it then the motor is not thay healthy, possibly will run backwards at times. (on some occasions)

He’s right. Especially if the windings got overheated and have a partial short they’ll make the motor spin in reverse.


If a brushless motor doesn’t want to start, the worst thing you can do is force it to start (give it more throttle).It pulls way too many amps from the esc.

 

[blackgoat04]

I sent Arrma(horizon) a email about the cogging. I just replied back to the same guy that sent me out the other 2 motors. ???He replied back with "
Hi Chris

That cogging means that there is something wrong with the motor, I have placed an order for a replacement motor and pinion gear. They will ship out on order M9*.

Have great day


??????I think this guy might be a robot. That's the third motor!!
I replied again and said that the car randomly stops and the ESC starts beeping but steering still works... He replied again

Chris

That is possibly due to the motor cogging causing the esc to go into thermal protection. Let see if the new motor will take care of that.

Thank you

??I'm done!!!!!

 

[bicketybam]

I sent Arrma(horizon) a email about the cogging. I just replied back to the same guy that sent me out the other 2 motors. ???He replied back with "
Hi Chris

That cogging means that there is something wrong with the motor, I have placed an order for a replacement motor and pinion gear. They will ship out on order M9*.

Have great day


??????I think this guy might be a robot. That's the third motor!!
I replied again and said that the car randomly stops and the ESC starts beeping but steering still works... He replied again

Chris

That is possibly due to the motor cogging causing the esc to go into thermal protection. Let see if the new motor will take care of that.

Thank you

I'm done!!!!!

For what it's worth, I swapped in a BLX 185 with the BLX 100 motor and it still cogged. So maybe it does have to do with the motor

 

[blackgoat04]

For what it's worth, I swapped in a BLX 185 with the BLX 100 motor and it still cogged. So maybe it does have to do with the motor

Not super knowledgeable on this, but our motors don't have a lot of high tech circuitry in them. no boards etc. just wrapped wire and leads.....as far as I know. I could be wrong though

 

[Megasty]

There are ways on the motor end for it to cog, but they all involve damage in some way. Spent bearings which shrapnel makes its way to the rotor. Using screws that are too long contacting the copper wire & grounding itself to the motor mount (the anodizing material & not the motor mount itself). Damaged motor wires contacting each other or anything else (that's an obvious one). The best one is the copper wiring oxidizing so much that it limits current transfer but the motor has to be fairly old for this to happen - & yes, the last one happened to me

 

[DoNoHarm]

All my dead motors died from just wearing out. Never had one actually have a can issue, always been the rotor.

 

[blackgoat04]

All my dead motors died from just wearing out. Never had one actually have a can issue, always been the rotor.

well for fun I swapped motors. I put in the 3800kv that Horizon sent me for warranty (bad bearing). Runs smooth as butter. I got to run it for about 5 minutes before I had to get back to work. but it did not have any cogging issues. I need to drill out a couple of holes on the motor mount so I can change to different gearing. when I get home this evening I will be able to run it a lot longer and see how it goes.

 

[blackgoat04]

well the car runs fine as far as power/torque but.... it burns through battt like crazy. I swapped the fuze 3800kv in just to test the cogging issues. ESC is fine though, so that's a good thing. So both batteries lasted just about the same amount of time. Roughly 6 minutes. Usually my larger battery will last over 20 minutes if I don't do a lot of speed runs. I received the Dynamite 2800kv in the mail today. I'll try it out tomorrow. Since the granite doesn't come with adjustable motor mount I was forced to use the 15t with the 3800kv today. I'm sure that played a role in battery usage. Well here's a video of today's abuse. I imagine this big hill is a huge stress for the motor. it sure does break parts pretty quick too.

motor/ESC temps at the end of the video. battery was around 100

video of my poopy/abusive driving on a big hill

 

[Megasty]

well the car runs fine as far as power/torque but.... it burns through battt like crazy. I swapped the fuze 3800kv in just to test the cogging issues. ESC is fine though, so that's a good thing. So both batteries lasted just about the same amount of time. Roughly 6 minutes. Usually my larger battery will last over 20 minutes if I don't do a lot of speed runs. I received the Dynamite 2800kv in the mail today. I'll try it out tomorrow. Since the granite doesn't come with adjustable motor mount I was forced to use the 15t with the 3800kv today. I'm sure that played a role in battery usage. Well here's a video of today's abuse. I imagine this big hill is a huge stress for the motor. it sure does break parts pretty quick too.

video of my poopy/abusive driving on a big hill

6 minutes!? Even my dirt cheap floureon 3s 5500 lasts for 20-25 in my Granite BLX, stock of course. How is your ESC draining them so fast. That's just weird. I know these ESCs are junk. Maybe I haven't ran the 3 I have enough for them to screw up. My Typhon doesn't have 10 runs yet because of this stupid weather. But I've put both the Granite & Senton through the ringer & I've only replaced the shocks on both.

 

[blackgoat04]

6 minutes!? Even my dirt cheap floureon 3s 5500 lasts for 20-25 in my Granite BLX, stock of course. How is your ESC draining them so fast. That's just weird. I know these ESCs are junk. Maybe I haven't ran the 3 I have enough for them to screw up. My Typhon doesn't have 10 runs yet because of this stupid weather. But I've put both the Granite & Senton through the ringer & I've only replaced the shocks on both.

not sure.veven climbing that hill in the video my batteries lasted a lot longer. you think it's the 3800kv with the 15t pinion that burned through them so fast. did you see the motor/ESC temps at the end of the video

 

[Megasty]

not sure.veven climbing that hill in the video my batteries lasted a lot longer. you think it's the 3800kv with the 15t pinion that burned through them so fast. did you see the motor/ESC temps at the end of the video

The heatsink is definitely doing its job. The 6s cars need a huge heatsink like that. Those cans can reach 170 on 6s & constantly thermal out the ESC. I never had a problem with ESC temps. Most ESC problems are with voltage regulation, mosfets making the caps turn fireworks, & the damn thing getting wet & shorting out.

 

[blackgoat04]

The heatsink is definitely doing its job. The 6s cars need a huge heatsink like that. Those cans can reach 170 on 6s & constantly thermal out the ESC. I never had a problem with ESC temps. Most ESC problems are with voltage regulation, mosfets making the caps turn fireworks, & the damn thing getting wet & shorting out.

what temp is considered to high on ESC? what's the thermal cutoff point. got home and put the battery on the charger, charger said it was dead. So I guess the ESC didn't go out on thermal like I thought

 

[Megasty]

what temp is considered to high on ESC? what's the thermal cutoff point. got home and put the battery on the charger, charger said it was dead. So I guess the ESC didn't go out on thermal like I thought

The thermal point of the ESC is the motor (180-212). The motor will make the ESC thermal out. Most ESCs don't even need fans. The wiring from the motor can also get as hot as the can itself. That's how the ESC monitors the motor temps

 

[blackgoat04]

has anyone ever tried to make a port that will carry air directly to the motor. like ram air. maybe I'll mount a fan on the inside of the body hanging from the roof lol, cut a hole in the roof

 

[blackgoat04]

just slipped in the 2800 kv with a 20t. I think I could do the resting backflip if I had my wheelie bar on. This things got some torque....and some heat. did not get to run it very long. It is dark outside and I usually run into stuff when it's dark.