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Thread: esc question

  1. #1
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    esc question

    I took my sons summit out for some daddy fun in normal mode(we have been driving it in training mode) and I noticed sometimes when I pull the trigger, it doesn't go forward, the 2nd pull it goes. just wondering if this is some type of protection feature or whatever. It doesn't seem like there is a problem with the esc as probably 70-80% of the time it goes fine. I haven't experienced this with my other esc's so just wondering if it is the beginning of a failing esc or if its normal.

  2. #2
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    There is a delay from reverse to forward built in.
    I sent my esc in when it was doing as you described mine even turned off twice.

  3. #3
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    Quote Originally Posted by yellowufo View Post
    There is a delay from reverse to forward built in.
    I sent my esc in when it was doing as you described mine even turned off twice.
    so its normal then? I didn't have these problems with brushed escs years ago and my brushless lst conversion is forward only esc with reverse coming from changing the transmission. I'm probably just not used to how these ESC's work.

  4. #4
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    no its not normal to have to double tap the trigger from a stop to get moving,when you come to a stop will braking you will need to release the trigger then squeeze it again to go from brake to reverse or brake to forward, ide have to say that the esc is malfunctioning, or have you checked all the conections make sure they are all solid, maybe even try re binding the car to the controller

  5. #5
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    I just got one of these for myself and it sounds like mine is doing the same thing. Approx 1 out of every 10 trigger pulls, it just out right stops. I've only noticed it at slow speeds. It hasn't been too bad, but it is frustrating, not to mention worrisome. I just ran it in a small circle in the basement and thought I'd see what it would do if I gave it full throttle when it came to a stop. The LED on the ESC began to flash red. I recalibrated the transmitter with no change. I haven't tried resetting it yet, but my guess is that it's faulty.

    The kicker is... I wanted a brushed version, just like our sons. I ended up with this because the 7205 (brushed) was sold out everywhere.

  6. #6
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    yes, its like I pull the trigger and you hear the whining noise from wherever in the electronics, but the truck doesn't move, then you release and pull again and it moves. almost like it can't find the position that the motor is in.

    it only seems to happen mostly when I'm going and release throttle and try to pull the throttle again. going forward, braking, then forward again it doesn't seem to happen.

    at any rate, its not just me, my son has it happen to him as well. But otherwise the truck runs fine, not really sure what to do with it. I'd hate to send it off for repairs as my son uses it almost every day and its hard to explain to a 3 1/2 year old that he can't use his truck.

  7. #7
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    I plan on calling Traxxas tomorrow. I can let you know what I find out. I haven't been feeling very motivated though - fighting a horrible cold.

    I had the local hobby shop take a look at it. He couldn't tell me that it wasn't a protection feature, but that behavior - whether by design or a fault - was not something he was familiar with. I think what convinced him the most that calling Traxxas was the next appropriate step was that the ESC will go into lipo protect mode if you hold the throttle while in the stuck/stopped condition. I assured him that the battery was freshly charged and he verified that both cells were at 4.17 volts. If nothing else is wrong, that can't be right.

    Take a look at this video. This is exactly what mine (and sounds like yours) is doing:
    http://www.youtube.com/watch?v=ZYyk4KdiKMQ

  8. #8
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    Sometimes if it won't go while at low speed it is known as cogging. Very common problem with non sensored brushless motors. For the most part, brushless motors don't like to run very slow.That is why most crawlers use brushed motors. Sometimes, NIMH batteries will cause this affect to happen moreso than lipo, so you could give that a shot. This sort of thing used to happen on my stampede vxl all the time. If you go trying to make it happen, its gonna happen. I could make it happen all day long on purpose, but I eventually stopped trying to make it happen and just drove the truck. Also , not sure how good your LHS is, but the one I used to go to sucked. No one in that shop knew what they were talking about. It was a hobbytown, which is more of a national type store, so a local family owned business may be better if thats where your going. Before I got the vxl in the stampede, I also tried out a venom rc brushless system with horrible results. It had the same symptoms as you described, and eventually got worse to where it wouldn't move at all. I exchanged it for another, and within a day or 2 that one stopped working also. I then went with the vxl which was much better. Cogging can also have to do with your gear ratio though from what I've read. Can't remember the specifics but I researched it when I thought that was the problem with the venom esc. Either way, it could be that, or it could be a faulty esc as well. Traxxas has good customer service from what I hear, so if its a persistent problem just give them a call and see what they say.

    Edit: was just thinking after watching that video, it could very well be just the way brushless are. The really don't like to go slow.
    Last edited by stingeragents; 12-30-2012 at 11:00 PM.

  9. #9
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    let me know what is found out, its more annoying than anything else. my brushless lst2 doesn't do this, although its no where near as smooth running as the summit. For me its like if I don't use brakes and it just rolls to stop, it doesn't want to start until you release trigger and start again, but I have to think its not defective as it runs normally most of the time. its not like it stops while running or anything.

  10. #10
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    I tried disconnecting my servo and that didn't change anything.

    I talked to Traxxas Support and the rep decided to replace the ESC. If nothing else, he was concerned it was going to get worse or die completely. Mine doesn't roll to a stop. It stops dead in its tracks like in the video. You could be doing donuts, pumping the throttle, and it will just come to a hard stop. Behavior aside, mine was also going into lipo protect mode and that may have been a big part of the decision to replace it. Of course, I still haven't received the email with info on how to proceed and that means at least another day without my truck. They won't cross ship anymore, so I have to send mine in before they'll send out the new. I'm not happy about that.

    I highly doubt it is brushless cogging. That is a condition where the ESC doesn't know the position of the motor and is firing back and forth until the motor gets enough RPMs. I've only seen that under light throttle and visible as jittering or otherwise erratic behavior.

  11. #11
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    I just got a 1/16 summit and it's doing the same thing.I have several other models including the mamba max e-revo and have no problems going slow.My only concern is drivetrain damage from such a harsh stop.I find as long as you don't let the model slow down too much it won't do it or let it come to a complete stop

  12. #12
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    yea, mine doesn't do like you are describing, mine will drive normally once it starts moving, its just every once in a while if It stops and you pull the trigger, you will just hear electrical whine and it won't move until you release the trigger and pull it again. But it doesn't stop in the middle of anything so it seems like we have a different problem.

    Quote Originally Posted by firestorm View Post
    I tried disconnecting my servo and that didn't change anything.

    I talked to Traxxas Support and the rep decided to replace the ESC. If nothing else, he was concerned it was going to get worse or die completely. Mine doesn't roll to a stop. It stops dead in its tracks like in the video. You could be doing donuts, pumping the throttle, and it will just come to a hard stop. Behavior aside, mine was also going into lipo protect mode and that may have been a big part of the decision to replace it. Of course, I still haven't received the email with info on how to proceed and that means at least another day without my truck. They won't cross ship anymore, so I have to send mine in before they'll send out the new. I'm not happy about that.

    I highly doubt it is brushless cogging. That is a condition where the ESC doesn't know the position of the motor and is firing back and forth until the motor gets enough RPMs. I've only seen that under light throttle and visible as jittering or otherwise erratic behavior.

  13. #13
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    common problem of late, mine did same thing and after Traxxas replaced the ESC (2+ weeks) it was much better witth only cogging you would expect from brushless unsensored at low speed.

  14. #14
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    FWIW, Traxxas replaced my ESC and that fixed the "cogging" problem. It cogs like a normal brushless of course, but no longer abruptly stops and doesn't go into unexpectedly go into lipo protect mode.

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