BK+LMT Glitching/Cogging ???

[What's_nitro?]

Hi everyone, I just bought a new BL setup for my Rustler:

BK Warrior 12020
LMT Basic XL 5000
Tanic 11.1v 5000mAh LiPo

Yes I realize this is a hot setup, probably too hot but we will see. Anyways that isn't the issue. While bench testing I noticed around 2/3 and up through 3/4 throttle the motor glitches/coggs like mad. It actually stops and revs up again about every 1/2 second. There is absolutely no way I can drive the vehicle like this. To my knowledge the BK doesn't have adjustable timing; and the LMT is a 2 pole motor so there should be no problem there.

Any thoughts and/or suggestions would be appreciated.

Thanks, Steve.

[BrianG]

Welcome to the forums!

When you say bench testing, do you mean with the tires in the air? If so, what you're seeing might be just the motor spinning back down until it catches up to the reduced throttle and kicking in again. Have you tried running it on the ground?

Also, are you using a UBEC or the BEC built-in to the ESC?

[What's_nitro?]

Yes, bench testing with motor installed and tires in the air. BUT the same thing happens when I remove the motor and just hold it in my hand. And this happens when I am on the throttle in that 2/3 to 3/4 RANGE. If I accelerate to full throttle, it will glitch as I pass certain points along that range and the same when I decelerate to a stop without engaging the brake. I am using the BEC from the BK but I always disconnect the steering servo during testing b/c it's digital and makes lots of annoying chirping sounds. The BEC is rated for 3A anyways so I wouldn't think that would cause problems.

[MetalMan]

Do you happen to have another radio to try out?

[What's_nitro?]

Yeah, actually, I do have other radios I could try. Are you thinking it's a glitch in the way the radio programmed the ESC? I'm using a Spektrum DX3.0 system but I'll try it with my old Futaba FM and see what happens.

[squeeforever]

Try that and see what happens. Also you might want to try and reprogram the ESC. That might be the problem. Be careful though, running it unloaded like that has actually been known to fry ESC's and motors...

[What's_nitro?]

Well I tried programming it with the Futaba FM and the same problem arose. Also for kicks I tried the stock Traxxas AM radio and it was no better. As far as reprogramming the actual ESC how would you do that? The Warrior doesnt have a PC link or any other obvious ports on it.

Here you go: http://www.rc-monster.com/forum/showthread.php?t=8

[What's_nitro?]

Yes, thank you, but I know how to (re)program the radio to the BK. I did that for both of the other radios. By "reprogram the actual ESC" I was talking about the firmware inside the BK. Anyways it probably can't be done. Do you think the issue could be EM feedback? AKA certain speeds generate resonance in the motor power wires as the current through them is sufficient enough to create a field which induces a signal in the other two wires. This causes the BK to "spaz out" due to the interference. Just a thought...

[Serum]

I have got the very same problem with my warrior when i am using it on my 1350kv 6 poler on 14 cells. (with the tires in the air)

the 5000kv is a loaded value. Lipo's are about 4.2V fresh from the charger, so comparing that with the problem i've got, and looking at the (loaded Kv) of the motor it might be hitting the controllers RPM limit.

Put it on the ground and give it a go. that's my advice.

My maxx ran fine with the wheels to the ground, only suffered this problem with the wheels in the air.

[What's_nitro?]

Well that is interesting. I didn't know the LMT's were rated with a load. BUT (theres that word again) my last tests were done with the battery discharged to its storage voltage of 3.6 volts/cell (because I don't plan on driving it soon). As far as driving it to see whether the problem is extreme RPM, I'd rather not risk exploding my differential or possibly the whole transmission. Picture in your mind this setup geared 22/87 running at let's say 45-50 MpH at 2/3 throttle - and then instantly stop the motor - and just as the gears have all lashed back hit the throttle hard again. Repeat. I don't see the transmission lasting very long in this scenario. Not to mention it would probably wheelie every time, too.

[Serum]

A gentle finger offers help.

after one F-up, you know what to do.

[Serum]

What lipo's/plugs are you using bytheway?

[What's_nitro?]

Tanic Packs 3s 5000mAH 20-30/50C

[Serum]

how are the plugs/connections from the controller to the motor?