MMX8S/1717-1650 Heat Issues

[bicketybam]

Just got done running my new Kraton EXB with the Castle MMX8S/1717-1650 Kv combo and a 23t pinion. I set the motor temp cutoff at 180 degrees. It took SIX MINUTES to have the ESC shutdown for motor over temp. I waited somewhere between 8-10 minutes and started it back up. The motor was at 138.4 degrees and it took 3 more minutes to hit the cutoff again. I am extremely disappointed. I called it a day and pulled the logs.

Motor Max Temp: 170 degrees
ESC Max Temp: 198.3 degrees!

I got 9 minutes of runtime. NINE. My battery was at 3.79 per cell so that should give you an idea. I am going to post some graphs.

This is the motor temp:

Next is the ESC temp

Finally here is both temps combined with my throttle inputs. As you can see, when I started hitting it, the temps climbed quickly:

Ambient temperature was 81 degrees with 67% humidity.

If you opt for this setup you will have to run fans. I am really surprised that this 8S ESC/motor ran as hot as it did. We are talking about a combo that is close to $400. Maybe I was expecting too much. The performance is definitely there but color me nutty, I would like more than 9 total minutes of runtime. Is that too much to ask?

 

[KiTris ExtremeRC]

Just got done running my new Kraton EXB with the Castle MMX8S/1717-1650 Kv combo and a 23t pinion. I set the motor temp cutoff at 180 degrees. It took SIX MINUTES to have the ESC shutdown for motor over temp. I waited somewhere between 8-10 minutes and started it back up. The motor was at 138.4 degrees and it took 3 more minutes to hit the cutoff again. I am extremely disappointed. I called it a day and pulled the logs.

Motor Max Temp: 170 degrees
ESC Max Temp: 198.3 degrees!

I got 9 minutes of runtime. NINE. My battery was at 3.79 per cell so that should give you an idea. I am going to post some graphs.

This is the motor temp:
View attachment 90995

Next is the ESC temp
View attachment 90996

Finally here is both temps combined with my throttle inputs. As you can see, when I started hitting it, the temps climbed quickly:
View attachment 90997

Ambient temperature was 81 degrees with 67% humidity.

If you opt for this setup you will have to run fans. I am really surprised that this 8S ESC/motor ran as hot as it did. We are talking about a combo that is close to $400. Maybe I was expecting too much. The performance is definitely there but color me nutty, I would like more than 9 total minutes of runtime. Is that too much to ask?

A 23t is definitely a little high, I would gear down to a 20t.

 

[Knxwledge]

Not sure if i did it right but when i checked the speed calculator. You are geared for 88mph.

 

[bicketybam]

Not sure if i did it right but when i checked the speed calculator. You are geared for 88mph.

My calculator shows a top speed of 76.95 mph. In any event, I'm not sure dripping it 4 teeth is going to make a ton of difference. Maybe it buy me another 5 minutes. I am never flat out on the throttle, even when rotating in the air. I find it disappointing. Cryo-technology! ?

 

[LibertyMKiii]

My calculator shows a top speed of 76.95 mph. In any event, I'm not sure dripping it 4 teeth is going to make a ton of difference. Maybe it buy me another 5 minutes. I am never flat out on the throttle, even when rotating in the air. I find it disappointing. Cryo-technology! ?

MMX8s has run very cool for me so far and noticeably cooler motor temps. I assume this was 6s?
I am coming up with 84-88 mph on the calculator also. (either way 4-8 mph wont make that much difference)

I assume you setup your rigs similar with the max6 or max5 and other motors? How was the amperage in the logs? I have had motors that simply run hot and draw tons of power. Another exact same motor might perform better. No 2 motors are the same...

 

[gotnitro]

I'll be doing the 800kv mill geared up outta my limitless with the same ESC but with a WTF fan on top.

 

[robert@castle]

You might want to check that your ESC fan is working. The fan is supposed to turn on when the ESC hits 140F or 60C. Normally in the graphs you can see exactly when the fan turns on because the slope of the ESC temp line will change pretty dramatically. You temperatures seem to continue to rise at a constant rate.

Motor temps are about as high as we recommend customers run their motors, but they are built with a huge margin of safety in them. We got a 1717 to 120c(250F) yesterday and it was able to go out for another run an hour later. We don't recommend customers ever let their motors get that hot, but we regularly get motors over 100c(212f) in our testing.

A better fan for the ESC and a fan pointed at the motor are not bad ideas for this setup. Gearing down 4 teeth on the pinion would make a fairly sizable difference to temps of both because they wouldn't have to work as hard to accelerate.

 

[Megafandrew]

I run a 1730kv in a 8s Mojave and have no issues with heat. I think that 23T pinion should be your first look as others above mentioned. And get fans either way and you should be good to go! Also I found I built a lot of heat on a Tekno build I did with garbage lipos. I know C rating doesn’t really matter as some say but I got a better delivering lipo and it made a big difference. I think the esc, and motor were asking too much from the lipo previous if that makes any sense lol

 

[bicketybam]

You might want to check that your ESC fan is working. The fan is supposed to turn on when the ESC hits 140F or 60C. Normally in the graphs you can see exactly when the fan turns on because the slope of the ESC temp line will change pretty dramatically. You temperatures seem to continue to rise at a constant rate.

Motor temps are about as high as we recommend customers run their motors, but they are built with a huge margin of safety in them. We got a 1717 to 120c(250F) yesterday and it was able to go out for another run an hour later. We don't recommend customers ever let their motors get that hot, but we regularly get motors over 100c(212f) in our testing.

A better fan for the ESC and a fan pointed at the motor are not bad ideas for this setup. Gearing down 4 teeth on the pinion would make a fairly sizable difference to temps of both because they wouldn't have to work as hard to accelerate.

Thank you for the reply! I will take a look at the fan to see if it is working. I'll probably end up replacing it with something that runs all the time. The stock fans are pretty junky, no offense ???

 

[gotnitro]

Thank you for the reply! I will take a look at the fan to see if it is working. I'll probably end up replacing it with something that runs all the time. The stock fans are pretty junky, no offense ???

Just a pre-caution if you didn't already know. When you install a better 40x40 fan make sure your not screwing the fan mounting screws too far in, they will hit the tops of the ESC's caps. Very little margin in-between. Some of the aftermarket fans have deeper mounting holes and its easy to miss. Spacing washers or shorter screws are the fix

 

[bicketybam]

Just a pre-caution if you didn't already know. When you install a better 40x40 fan make sure your not screwing the fan mounting screws too far in, they will hit the tops of the ESC's caps. Very little margin in-between. Some of the aftermarket fans have deeper mounting holes and its easy to miss. Spacing washers or shorter screws are the fix

Do you have a link to a fan that will work?

 

[gotnitro]

Do you have a link to a fan that will work?

I like the WTF stuff, you can plug directly into the RX and will run on 8.4 if you set your BEC that high.

https://www.ebay.com/itm/Wild-Turbo...528595?hash=item5b6d490f93:g:LecAAOSw1iVbsn~3

 

[Hammer Down]

I would bet that sh!tty stock fan cover is the culprit. It’s too close to the blades, they break off and jam It up.

 

[bicketybam]

I like the WTF stuff, you can plug directly into the RX and will run on 8.4 if you set your BEC that high.

https://www.ebay.com/itm/Wild-Turbo...528595?hash=item5b6d490f93:g:LecAAOSw1iVbsn~3

Thanks you! ???