Gearing and Temp

[Phins Fan]

I'm in the middle of converting my boys Highroller to brushless. I've got an older Novak Supersport ESC and a Novak 4200 motor running on a 2S lipo. Niether have a fan currently hooked up which brings me to my questions: 1) What is too hot for brushless motors and esc's? I was running around 160 for both after only about 5-8 minutes of speedruns. I was basing my gearing off of a stampede VXL and have started with a 19/86 combo. Too high/low of gearing? He's a typical kid and impatient and wants to drive it asap. Going brushless definately woke the truck up and I've already upgraded the tranny to steel gearing and a ball diff but I didnt want to run it like this unless some of the pros think its alright with these temps.

 

[Metalhead Matt]

I'd drop two teeth on the pinion. That's a little warm. 150 is about as hot as you want either.

 

[Stroytika]

i have seen vast numerous amounts of posts saying 160 is more than fine. i would advise picking up a heatsink and calling it a day even if that. nothing heats up a motor like speed runs.

http://www.rctech.net/forum/electric-off-road/488392-brushless-motor-temp.html

i can dig up a thousand others if needed.

 

[Metalhead Matt]

It isn't so much the 160 temprature, it's how fast it got there. I play it safe. A two teeth drop isn't gonna make a drastic change in performance on a bashing level.

 

[Phins Fan]

Fair enough guys and thanx. I'm gonna pick up a set of pinions today going odds from 9 to 17 tooth. Bound to find something that will work and its not a race rig by any means so a low gearing will help in the bashing dept.

 

[2revo1maxx]

You compared the gearing to a stampede which is fine, but you have to factor in the extra 700 kv too......Of course it is a completely different truck, but that's also a faster motor.

 

[MudSlinger33]

My vxl systems both reach around 160-170 by the end of the run. IMO, anything above 200 is the danger zone.

 

[Phins Fan]

I regeared to a 17/82 combo and temps were around 120-130. I like that much better. When I talked about the Stampede gearing it was looked at as a comparable truck but I didnt think about the tranny gearing and final drive ratio. He is very happy with the current setup as it allows him to pull instant wheelies (gotta fab a wheeliebar now). The only real low point is its such a high CG truck that his first body he painted is gonna get beat fast!!

 

[hamz9561]

It will at least give him incentive to paint another, lol.

Sent from my SPH-D710 using Tapatalk

 

[Phins Fan]

I'll have to post pics ltr. He saw all my painting supplies and went crazy with ideas. Its a little loud for me but 10X better than my first attempt with liquid mask and an airbrush.

 

[Greywolf74]

I read that 168F is the beginning of the danger zone for BL motors. this is the point where the motors magnets start to loose some of their magnetism. It wont kill them at that point but they will begin to degrade at that point so I try and never let my motors go over 160F and I always put heatsinks and usually fans on them as well as my ESCs just to be on the safe side.

I also personally dont like to see my ESCs ever get to 150F I try to keep them below that.Anything over 135F on an ESC makes me nervous.

Same with Batteries if your batteries are going over 130F Id get higher C rated batteries. If your C rating is high enough your batteries should never get anything more than warm to the touch and if its high enough they wont even get warm.

 

[Phins Fan]

I've got the Novak fan on order for the ESC and found a twin fan setup for the motor. While his batteries tene to be fine I will keep an eye on some of mine. I have a couple that I run in my T4 that can get VERY warm once they start to die

 

[trax de max]

+1 with greywolf74.
Do the temp check where you would normally run and how you would normally drive.
You have to consider how quickly it gets to them temps. Also inside the motor is maybe 10 degrees higher.
If you checked the temps on a flat hard ground with little/no braking you should be under 140. But if you then ran it on grass and constantly braked, that temp with same setup could possibly reach 180+

 

[2revo1maxx]

The magnets will fade as they heat up, but the epoxy starts to melt around 180-190-ish, and that's when they come apart.

 

[darkslayor24]

the lower grade novak motors i dont like to get anything over 150. a higher grade motor i will run upto 160. the esc, shouldnt get above either 20 or 30 degrees BELOW what your motor is running. a lot of stops, and goes, and reverses is what mainly heats up the esc and motor.

 

[Phins Fan]

Its been running consistently around 130 for both. Or was until my boy shredded the new ball diff I put in it when I hooked up the brushless combo. I may just take everything out and put it in a B4 as theres more aftermarket/replacement parts available for the B4 than the Highroller.