Why brushless (inrunner) motors aren't best for crawling

[z50king]

I have ran a novak gtb against a novak timbuk2 and there is a big difference. I think the initial drive and current limiter are set lower in the timbuk2. It's smooth on the bottom

[wheelyking4x4x4]

Holmes hobbies was designing a sensored outrunner and it was going to be the ultimate but i think the project stalled. Brushed are the smoothest but have a much shorter life if you don't keep maintenance up unfortunately.

[Dostradamas]

Originally Posted by nigels_world

Before you get to excited you do realize how slow that's going to be, right? Snails will yawn.

Interested is far from excited.
I crawl, so slow is fine.
I am not interested in high speed, high priced, or trendy so when someone has an idea that works for them & may work for me I am interested.

[Calderwood]

Originally Posted by Dostradamas

Interested is far from excited.
I crawl, so slow is fine.
I am not interested in high speed, high priced, or trendy so when someone has an idea that works for them & may work for me I am interested.

I don't have any any trendy motors either. I couldn't afford them even if I could justify it in my head. The most expensive motor I own was $80.

Even in a fragile detailed scaler I think that low of a kv would be a negative but, if it is the right motor for your application then go for it. One of my planes has a 1000kv motor in it and It's the right motor for it.

[Dostradamas]

Originally Posted by nigels_world

I don't have any any trendy motors either. I couldn't afford them even if I could justify it in my head. The most expensive motor I own was $80.

Even in a fragile detailed scaler I think that low of a kv would be a negative but, if it is the right motor for your application then go for it. One of my planes has a 1000kv motor in it and It's the right motor for it.

Thanks for your input

[Weekend Crawler]

Would it be possible to run brushless out runners in the XR-10 with no guards for the spinning cans?

[Calderwood]

Originally Posted by Weekend Crawler

Would it be possible to run brushless out runners in the XR-10 with no guards for the spinning cans?

Yes it would be possible. That doesn't make it a good idea though.

[stevem50]

i have read through this and it seems that gearing and esc amperage/programming need to be further discussed. i have brushless in all my vehicles and get no cogging in my crawlers. the cogging effect when detected at the beginning of a run can be remedied with a simple gearing change, if you have no problem at the trailhead, and you get stutter midway through your trip, then the esc isnt properly suited to the situation. not the motor. i have 4 trucks on the bench that can prove my point and any time, they will crawl, snails pace, slowly and accurately.

then also look to other factors on your rig, example-when i went to taller tires and heavier wheels i would get a stall after a long climb at partial throttle to find an over heat issue on the esc to blame, i moved it to where the fan got fresh air and dropped 2 teeth on the pinion and no more stall. (aluminum gearheads with 3oz extra each and 5.75 pitbulls)

i also have zero maintenence on a brushless (my motor/esc combo is over 3 years old) where all the other guys i run with using brushed motors are always complaining about "dead spots" and fooling with brush/spring combos to get that sweet spot in the power band.

i think brushed motor guys are going to bash brushless either because they sell brushed motors or they have already spent too much money on them and dont want to admit they might have made a mistake doing it.

[Charlie-III]

Originally Posted by stevem50

I think brushed motor guys are going to bash brushless either because they sell brushed motors or they have already spent too much money on them and don't want to admit they might have made a mistake doing it.

I run brushed, never tried brushless (yet).

When I started with RC cars, there was no thing as brushless..... heck, there was no thing as an ESC! We used a servo & a resistor (like inside a slot car controller).

When I picked up 12th & 10th carpet cars again a few years ago (after they sat for close to 20 years), I still ran NiMH, brushed motors & very old Novak ESC's. I was darn near as fast as the guys with all the "new/cool stuff" including brushless & LiPO.

All I can say is that I've read about quite a few newer guys with brushless crawlers having cogging issues in their rigs. Yes, maybe it's their set-up.

[colebz]

I agree with you stevem50. I am by no means an expert in this field. I still consider myself a newb. I do think it has a lot to do with the setup, as you said. Gearing, weight of the rig, diameter of tires and so on. Just as important, is the esc you choose. I was running a cheap hobbyking x-car 45 amp sensored esc with a hobbyking x-car 17.5 turn sensored motor and 87/14 gearing in my wraith on 3 cell lipo. It would stall the same way you described, or if I got in any kind of bind. I switched to a 60 amp x-car esc and would only get stalling at the end of a long run. The esc was getting hot. I was able to borrow a mmp, ran it for a pack and it was butter smooth, in every situation. Only time I got stalling is in a bad bind on rocks. Next, I tried a hobbyking x-car 120 amp sensored esc in the wraith. Same results as the mmp! Been very happy with it for at least 6 months, and it was 38.95!

[stevem50]

i dont have anything against brushed setups, but i need to ask what the draw to them is... you guys swear by them even with their drawbacks.my brother went and got a novak setup for his last build and spent over 200 after the bec was factored in. i had better torque, slow crawl, and higher top speed on same gearing and both on 2s. he got maybe half way through the summer on the motor's 1st set of brushes, then by sept he had so many issues dealing with it that it got yanked and replaced with the setup i run. this weekend i went out with a few guys, most with brushed and after handing off my controller, i converted the most staunch of brushed advocates. when i told him that he could get my setup for $60 he thought i was joking...then i told him how old it was and he was hooked

[Meatwad]

I'm a fan of sensored brushless setups, but they will never be as smooth as their brushed counterparts. The free rolling period between application of throttle, letting off throttle and drag brake always kills me. If there can be a variable drag brake option similar to the cheat function of the castle systems, then this would be a non issue.

For normal trail running, these are non issues for the most part. During actual crawling however, these can be deal breakers for some.

[OTHGbronco82]

Originally Posted by stevem50

but i need to ask what the draw to them is

Simple, you can take a brushed motor into water and it will still run. That's with not having to waterproof the motor. With brushless you have to waterproof the motor which will probably void the warranty because you "altered" the motor and used it for something it wasn't supposed to be used for, which is going into any water on purpose. Plus they're cheaper.

[88RRC]

I can't stand brushed anymore. I ran it from 2010 to late 2011 and was very happy. Then I burnt up a few esc's(on 2cell, and not in water), brushes on a motor, and just got sick of fighting heat. Then I found brushless, I've found it's smoother, torquier, faster, cooler, and really not much more expensive than a high end brushed setup whether it be Tekin, novak, castle, or Holmes. I've never had a problem with cogging that wasn't easily fixed by either changing or re-seating the sensor cable. I've also never noticed this "free-rolling" as previously mentioned. Only problems I've had are with getting esc's wet. That's my fault for improper or not waterproofing. Only reason I see for ever going back to brushed is for a dedicated water rig. Then I'll just get a waterproof HH BRXL, and one of his cheap $10 27 turns.

Ben

[88RRC]

Originally Posted by OTHGbronco82

Simple, you can take a brushed motor into water and it will still run. That's with not having to waterproof the motor. With brushless you have to waterproof the motor which will probably void the warranty because you "altered" the motor and used it for something it wasn't supposed to be used for, which is going into any water on purpose. Plus they're cheaper.

This is kind of an iffy subject. Basically the way I see it is all that needs waterproofing is the sensor board. Other than that all it needs is regular maintenance ie. Keep it clean, change bearings, etc. I've seen a bunch of brushed motors not make it off the really wet trails due to killing brushes and bad bearings. One of them my own. You also void the warranty if you accidentaly get it wet so who really cares if you void it by waterproofing, conformal coat the sensor board and be done. Worse case they make a remover for it.

I ran for nearly 30 minutes like this when after I'd exited the water and started heading back towards the car the motor started beeping and my old but freshly waterproofed cheapo ESC smoked. NEVER did it cog while under water only afterwards when it started freaking out did it cog:

I think all the motor needs is a good clean, new bearings(could have used them before) and a sensor board. I just wrote off the esc since the magic smoke came out. When it died I quickly disconnected the battery and chucked it back in the water to cool it down. One of your points I can't argue is that brushed motors are cheaper.

Ben

[stevem50]

here is another side to this- now the brushless guys are coming out of the woodwork, why run sensored? the torque benefit of sensored vs. sensorless is marginal. if you are a swamper, run sensorless and soak it all you want. i have had issues with sensored motors in the past (still not as bad as brushes) but sensorless motors dont mind water at all.

there is a common thought that sensored inheritly have more torque available due to motor design, but if more power is needed for a truck that gets wet, skip the sensors and opt for a 3660 or 3674 size can, or go 4 pole. actually the 3674 motor in my tubeframe flatbed was rated in horsepower!

[Calderwood]

Originally Posted by stevem50

here is another side to this- now the brushless guys are coming out of the woodwork, why run sensored? the torque benefit of sensored vs. sensorless is marginal. if you are a swamper, run sensorless and soak it all you want. i have had issues with sensored motors in the past (still not as bad as brushes) but sensorless motors dont mind water at all.

there is a common thought that sensored inheritly have more torque available due to motor design, but if more power is needed for a truck that gets wet, skip the sensors and opt for a 3660 or 3674 size can, or go 4 pole. actually the 3674 motor in my tubeframe flatbed was rated in horsepower!

I run both sensored brushless and brushed. IMO sensorless brushless motors suck compared to the other options. A 4 pole sensored brushless motor will be able to be geared much taller than the sensorless counterpart without inducing cogging. This means when both motors are geared for no cogging the sensored motor will be way faster, especially when you consider that the sensored motor can be a higher kv without cogging.

The brushless motors work great for scalers and trail rigs. Mine are even completely waterproof. They do not have the low speed resolution necessary for comp crawling though. This is especially evident when stopped pointed down hill. The down hill start up of brushless motors is terrible. This start up issue is reason enough all by itself to use brushed for comp crawling.

I keep the low kv out runners in my 3d planes...

[stevem50]

this is the same thing i have heard and read over and over, but in reality on the rocks its not true. my truck simply does not cog or stall, and there are 50 youtube videos that show it. i run a cheap 3650 can tacon that will creep as good or better than the scx with a hh setup and a trailfinder with a novak goat in it. then on 3s it will wheelie over backwards on flat ground.

i think there needs to be some kind of tuff truck comp to settle this on youtube. perhaps an tractor pull style first, then maybe a set incline, say a 12ft 2x12 at 45 degree angle that you need to climb as slow as possible. like reverse drag racing, longest e.t. without stall or cogging wins, 3rd event would be a true drag race.(e.t. over measured 132 ft) all done the way they run "true street" events for full size cars. once you begin, no popping the hood. one continuous camera shot detailing drivetrain, battery, and then the run. no switching batterys, NO EDITING.

who is in?

[colebz]

When I was running the smaller esc with the 2 pole 17.5 turn motor, I would have the downhill issue described by others. When I switched to the 120 amp x-car esc, it got better, but it would still happen while coming down steep inclines. Same with the mmp. I had a 1/8th scale 1900kv 6 pole sensored motor lying around for another build and figured I would try it out. Glad I did! I dont have the downhill issue with this setup. When I apply a small amount of throttle while going down a steep incline, my wraith will creep slowly. The motor made my truck heavier, but its all down low and it side hills and climbs better now, too!

[Calderwood]

Originally Posted by colebz

When I was running the smaller esc with the 2 pole 17.5 turn motor, I would have the downhill issue described by others. When I switched to the 120 amp x-car esc, it got better, but it would still happen while coming down steep inclines. Same with the mmp. I had a 1/8th scale 1900kv 6 pole sensored motor lying around for another build and figured I would try it out. Glad I did! I dont have the downhill issue with this setup. When I apply a small amount of throttle while going down a steep incline, my wraith will creep slowly. The motor made my truck heavier, but its all down low and it side hills and climbs better now, too!

Do you have any video of the startup from a stop on a downhill?