Always Dreamin

My video is made and uploading. My youtube name is NoShelfQueen. It will be up later tonight. I'm going to dinner, but keep checking, should be up within the next 10-20 minutes.

http://www.youtube.com/user/NoShelfQueen

I have some using the VXL esc too. In this video is shows literally 0 cogging. Plus tons of HP.

simplecj

You know it's the esc that causes cogging... otherwise traxxas would have fixed the motor not the ESC. Granted that perhaps motor design does have an impact on the tendancy to cogg, what it comes down to is how the controller handles the motor.. end of story.. smart a**..

I'm an integrated engineer, what are you?

simplecj

BOO!!

Access

If you want to see cogging, try creeping along at speed less than 10cm per second. Unless they've made some revision, it starts to make what almost sounds like a clicking noice and will eventually just shut down if you do it long enough. At least that's what it did for me, I posted a video:
http://www.youtube.com/watch?v=pKdRFDuyoVo

vge

Wow, now I have truly realized that some people have way way too much time on their hands. Why in the world would you even run your rc that slow? I mean come on now. I can't believe people are really bickering and complaining about that. If that is what "cogging" is you people are straight retards. I guess I have never seen it before because I have never driven any of my rc's that slow before to notice. As a matter of fact I don't even think my 8 year old daughter has ever gone that slow before.

Access

I'm not sure where people get these explanations... seriously cogging is much simpler than this.
In RC we use the term 'cogging' to refer to the what happens in some BLDC sensorless systems when you try to go very slow.
Again see the video I posted above to see what cogging looks like.

The Back-EMF method to sense the rotor position stops working somewhere between 60-300rpms depending on the precision of the ADCs or whatever other sensors they are using to measure back-EMF. Below this the ESC has to use some other algorhythm to start the rotor spinning. A sensored motor and ESC combo does not have this problem at all, it can tell the location of the rotor even at rest. That is why the GoaT is really the only BLDC setup that works well for crawling. Anyways, among sensorless ESCs, this quality of this starting algorhythm is what determines the level of cogging. If you try the mamba max with the original firmware there is some cogging. But with their latest version (used in the video above) you can see that they have almost completely eliminated the cogging at low speeds. It's still not controllable enough for crawling, but out of all the sensorless ESCs I've used it does the best in this respect.

That a firmware update can change the level of cogging should alone rule out the below explanation; if a firmware update can fix it then clearly it is the ESC that is the cause and no the motor.

vge

Honestly chief if that bothers you, then maybe you should get into Crawling and buy a Novak Rooster for crawlers or something in that area. Also they have 55t motors for that speed as well. No one in their right mind thats not into crawling and I am sure no one is buying these for crawling. Should even be complaining about that issue. That just goes to show you that some people just pick issues with Traxxas just because. I mean gimme a freakin break. Please tell me what and when you would need to drive that slow with a brushless setup thats not in a crawler.

Access

It's called crawling, or "rock crawling" sometimes, and there are whole forums devoted to it; I was at a meet today and locally the crawling meets have more people show up than the racing meets. You can knock it all you want but it's out there and the GoaT (the first system in the video) is practically the only brushless that works. There was one guy with an outrunner (sensorless) but that didn't work too well. It's either the GoaT or brushed and the control on the GoaT is simply unmatched, anyways kinda OT but you brought it up... no need to get all worked up over a 3 minute video.

And racing it can make a difference too, especially if there is a heads-up start, these starts almost invariably lead to traffic jams and the difference between a little bit of hesitation or a good solid start can mean that you make it out in front of the pack or get stuck in (or behind) the jam.

And with the mamba's latest firmware update, you can find other threads where people just comment it is smoother, easier to control, throttle is more precise, etc. To me it's just a combination of all these little details, Castle pays attention to the details and Traxxas is just looking for something good enough to satisfy the RTR "buy it, bash it" crowd. Little things like the LiPo soft-cutoff (with the mamba) at a voltage you set, higher or lower if you please; vs. with the VXL it is a hard-wired voltage that just kicks it back into 50% throttle mode.

vge

Why would you use a vxl system for crawling you retard? I know what a crawler is. I also know that you dont use traxxas VXL's to crawl. Heck I have a Clodbuster scale crawler. Dude that complaint is so over the top that really from this point no one should even respond to such pointless crap. People like you that complain about things like that need a friend or two and need to get out side a little more.

Access

Some people are perfectionists, it has to be perfect, an attention to detail, etc. Others invaribly turn to ad hominem attacks when someone expresses a point of view different than theirs or one they cannot understand... but it's just the way people think, expressing a different point of view doesn't have to be a threat. It just is what it is.

vge

I think your just trying to be nice here. You show me one person that is some what into crawling that would even look at a Traxxas VXL system. They probably would not even be able to get in any events with that mess. If your gonna crawl there are tons and tons of other options. Dude thats like dropping in Lamborghini engine on a wheel chair. Even in real life the guys that do scale crawling don't drop crazy high rpm engines in their crawlers. They drop high torq engines in. It's pure stupidity. Thats like complaining to Porsche that the 911 turbo is too fast because all you need are a pair of sneakers. Yes both are used for technically the same thing, but are completely different means of getting to the same place. If you wanna crawl why strap on a jet pack to your back WOOT and wonder why you cant go really slow? People that complain about things like that do the hobby a disservice. Traxxas has brought brushless to the masses and made it very affordable. Why knock them for an issue that really should not be an issue. Traxxas doesn't make crawlers. Traxxas made the VXL system for one thing and one thing only.....to go fast. I bet they never tested it at those speeds. But really who cares?

simplecj

My VXL would sometimes cogg bad as I tried to accelerate from a stop. It would cogg at speeds above what would be useful for rock crawling, I would just be trying to cruise past some obstacles at like 1-2 mph and it would cogg. Only time it didn't cogg is when I was going full-out. It was very frustrating!

I'm glad to hear they have changed their design... they shouldn't have every released that crappy one in the first place.

EDIT: Thanks Access for backing me up on the fact that it's the ESC that causes cogging. Sorry I got pissed... stupid people...

Always Dreamin

http://www.youtube.com/watch?v=lCawOSqis9s

There it is... I got up to about 90% throttle in the video. That's just me doing everyday driving, not one cogg.

vge

Unfortunately chief that was their first attempt. So I am sure they did not expect it to happen like it did. But like a good company, they saw the flaw, took in the complaints and made a good fix. What do you expect? So many companies would have done nothing. So at least they have and people should respect them for that. Honestly I wonder if this cogging has to do with other issues that are related to other things in peoples electronic setup. I am going to go test my vxl setups and see if I have any of this cogging.

vge

Funny thing is, I think your going to fast to see cogging according to what people are saying. You need to be going crawler speeds.

Always Dreamin

I took off from a dead stop a couple of times, In the dirt.

Access, you know what you were saying about how the VXL would cogg until it finaly just stoped working? That happened to me for a while! I've had 5 of them, the first 4 didn't do that. This new one with the plugs coming out did when I got it. It would make a ticking noise, and the longer you did it, the more throttle you had to give it to get it going. Then enventually, it would just go off, and I would have to turn the ESC off then ON. I trimmed up the throttle, and it hasn't been as bad. Then again, this is the first VXL I've used with the Fasst radio, so that may be the problem.

simplecj

Now I'm wishing I'd have got some video of my cogging problems... it wan't just at crawler speeds. Crawling refers to barely moving. I couldn't even really coast around at 1-2 mph without cogging and it would even cogg just starting from a stop. I'd ease into the throlle and before the car got up to speed it would cogg, sometimes I'd even see the wheels jerk backwards before the car really got moving.

As for AlwaysDreamin's video, you already said you got the revised ESC from Traxxas so if they fixed the cogging issue then of course you don't have any cogging problems cause it's been fixed, duh!

Also, it seems even with the older set-up some cogged worse than others. Mine I think was particularly bad. I wasn't the electronics and it wasn't the batteries. Everything was stock electronics and I was/am using premium A123 LiFe batteries that can deliver max amperage to the ESC.

Always Dreamin

I might consider buying a Mamba combo, or something... Your video was great Access. Mine doesn't do it quite as bad, but it does do it.

Always Dreamin

Probably. Mine will still cogg. My Mamba wasn't as smooth as the one in Access's video.. It's making me wonder.. [&:]

Access

It's good they redesigned it. A lot of people rag on them just b'cos 'they're traxxas'. If you have a newer unit test it and post your results as far as the cogging. I have one of the original ones and it wasn't very hard to induce regardless of the battery setup (3s LiPo).

The terminology a lot of people use here is "cogging" = the thing shown in that video, "stuttering" is the much more common problem with a "high-power" ESC / motor pulling so much power that the battery voltage drops below the point where the ESC or receiver works and it drops out.

As for the mamba in the video, it's an optimal setup (3s and gearing for running on tough surfaces like grass). Though the VXL was just as 'optimal'. I can still get a little bit of hesistation or cogging on the starts with the mamba, even with the latest firmware, running with GP3300 NIMHs or something similar.

Always Dreamin

If that's true, why does it do it at low throttle and not at high? I would think the ESC would pull more amps at full throttle then rock crawling speeds. Just saying...

vge

I will charge up some batteries and take some vids and see if mine does that.

simplecj

Actually the amps are higher when starting from a stop. There is much greater resistance to rotation at zero or low speed, once you get moving it doesn't require full amperage to continue at that speed or to accelerate. Maximum amps are hit when you punch it off the line.

However I don't think that was my problem. I had a 10v A123 pack that can deliver up to 140 amps continuous, far more than the ESC requires and I'm sure I wan't dropping below min voltage even at max amperage to the ESC.

Also, my cogging was not just the noisy stuff where it hesistates, it would actually jerk the wheels backwards or lock them up like it was braking. And sometimes if I tried to accel too slowly then I'd get that problem where it wouldn't even move, just made some noise then turned off...

My Sidewinder has never done that, well since I got a good radio in it anyways.

osteologation

I got my Velineon in Feb 08 and the only probs I've had is when its cold out sometimes it loses reverse (why idk). Also the on/program button will get dust in it enough to make it stick and I've had to take it apart to clean it up. For as much as I've ran it I'm happy really. I paid 139 at the LHS. It doesnt cog or stutter hardly except at redicuously low speeds. Nothign like that video. I'm no traxxas fanboy but all the LHS really carry is traxxas stuff and its just easier. and as far as speed goes I have a Slash with velineon 18t pinion and 2 of my friends have slashs with mamba 5700 with 16t pinions and all running team orion gp3900's are about dead even after a city block. The worst cogging I've seen was teh mamba 5700 with ebay special 3300's. Horrible. But that was def the batts.

JPerrone

I hadn't even thought about getting a Velineon for my Midnight Pumpkin or Grasshopper until I came across this thread; but now I think I might! Reason: I don't really need all the programming of the Mamba, and I don't want to also change out my radio system.

For both cars I got LiPos to increase run time not to go faster. But then I found out about the low voltage cut-off thing, so got a Novak LVC. Still haven't installed it, will do so soon. The reason to consider getting a replacement ESC is
1) My stock ESC in the Pumpkin is acting up, haven't done all fault-finding yet but it is possible I need to replace it and
2) Even though I will be running the stock motor, I think it will be able to draw a few more amps from the LiPo than it could with the NiMhs I had. So, a Mamba or Velineon & LiPo & stock motor should run cooler

Any thoughts?

I have a Rustler VXL and I gotta say that I have not had any of the problems indicated by others. Maybe I am more forgiving of minor faults like low speed cogging etc. I think my solution for stuff like that is: "don't do that"

Regards