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  1. #1
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    summit stalls out under throttle

    Okay, so here is the situation. I've got a summit with a 7.5T novak hv pro and it seems to work pretty good except for when I am in high gear (yes, only in high gear), if I punch the throttle from a dead stop, the truck will lurch forward just a little bit, stall out for just a split second, and then take off at full throttle like it should. It doesn't do this all the time but enough for it to be an annoyance. It's not really a problem for me, but it keeps me from doing wheelies. Do you think it has anything to do with the fact that the motor is sensored? Also, I am trying to decide if I should increase my pinion size. I am currently running a 14t pinion with the 68t spur and the last couple of days that I have been running it, it has only been about 40 degrees farenheit out. After about 10 minutes of running (lots of high gear, higher speed), the motor heatsink is just barely warm to the touch (I think somewhere below 100 degrees farenheit, I can't remember the exact measurements I took) and I can't feel any warmth on the esc heatsinks. Judging by that, I could move up in pinion size. But when I am driving, if I accelerate in high gear as quick as I can, the car gets up to speed pretty quick, but when it reaches full speed, I can hear the motor almost trying to rev up even higher but slowly. What do you think this means? Thanks for your help.
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  2. #2
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    it sounds like cogging to me.. yer batterys may not put out enuff current to supply the esc with what it neads... and when its cogging u need to gear down to help prevent it go down to like a 12t pinion and see if that helps any.... or set the punch on the esc so it doesnt start out on full throttle it'll start out at a lower power then togo full throttle... or just easy into teh throttle instead of just hammering it
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  3. #3
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    Are you running lipo or NIMH....I think the ESC may have protections that could cause the symptom you are talking about. I ran a HV 4.5 in my Emaxx and really liked it, I ran a 10t pinion....had no issues at all.

    Does the ESC flash a code or the led change color?

    If you have NIMH the load may be dropping the voltage...or on LIPO it may see the high amp and mistake it for a locked rotor.

    You may want to check the manual I think there is a small section on troubleshoting

  4. #4
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    Sounds like your running NIMH, or very weak lipo, and they can't handle the amp load at full throttle. Either the LVC is kicking in or the BEC is being starved for power. Get better batteries or gear down.

  5. #5
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    Thanks, that is helpful. Yes, I am running Nimh batteries. I would gear the car down but I still want to get some good speed out of it, and even with the 14t pinion it's probably maybe going only 35 mph. So it would go a lot slower with a 12t pinion. I am pretty sure that it is not overgeared right now, and it has plenty of power in low gear. The problem I am having is not because of the lvc, because I have it disabled. I think I will just get some better batteries. Probably some ******* 30c 2s lipos.
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  6. #6
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    With a 14t pinion and 68t spur, assuming stock tires, your geared for 42 mph! That is too high. ERBE's running 4s with twice the watts in a MMM only gear that high. Gear it down to 12t pinion which will still be good for 36mph and be easier on the batteries, ESC, and motor and it may actually end up with a higher top speed due to the motor not straining.

    That's the big downer of the Novak systems is their high Kv and only a 550 size motor which limits torque and watts to haul around a big, heavy truck like the Summit.

  7. #7
    RC Turnbuckle Jr.
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    Strange, you seem to be having the exact same issue you complained about before; I told you then you were overgeared and the nimhs werent helping, yet you have done nothing to remedy the situation and decided to start another thread complaining about the exact same issue; you need to gear down and buy some better batteries.

    http://traxxas.com/forums/showthread...t-and-powerful
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  8. #8
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    Okay, to clear a few things up. First of all, I haven't exactly measured the speed, but my truck is definitely not going 40+ mph. I have a S-maxx, so I know what a speed comparison would be. And yes, ArmyofDarkness, you told me I was overgeared, but quadiak (who ran the same system in his summit for a time), told me that in his firsthand experience with the system, it was not overgeared with a 14t pinion. So, I actually don't know why I asked about gearing. I now see that it was kind of stupid. And I haven't tried it yet, but I will try a 12t pinion and see what happens. Furthermore, I am not complaining. I am simply stating an interesting thing my truck did (stalling) and asking people's input on the matter. I also asked about gearing because I have found that more opinions are always better. And really, this thread was mainly about the stalling issue (hence the title) but I thought I would toss a gearing question in there too. Is that a problem? And now that some very helpful people have given me good information and not just criticized my habit of asking a lot of questions, I know the answer and I feel stupid for not realizing it myself. Seriously AOD, it seems like almost every post I see from you is ripping on someone. Why can't you be a little nicer about things? And like a lot of people these days, I have to think before I just drop $80 or so to get myself a couple of lipos. I'm trying to work with what I've got. Anyways, sorry people. Does anyone else have any comments? I believe this thread has served its purpose.
    Why can't other people share my opinions?

  9. #9
    RC Turnbuckle Jr.
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    You posted a video of the truck stuttering before in your last thread; the issue you have now is the same one- go figure if someone ( has the balls / nerve / courage ) to point out that making another thread is pointless as you arent going to get any more / new or useful input on the subject. Fact is the truck is overgeared with those massive tyres, the batts cant supply the current, so the motor is stuttering at low speed; sensored motors are ment to cog/ stutter less than sensorless ones so unless the esc is damaged as a result of the overgearing then being sensored isnt creating the issue; quite the opposite ordinarily. If you look on the novak website you'll see 12-14/68 is recommended with the new emaxx which has 5.9" tyres & weighs ~9lbs vs 7" & 13lbs for the summit. No amount of opinions will override the manufacturer's recommendations and common-sense;- I've ran a 13lb truck with a hvmaxx and it didnt like it one little bit, couldnt gear for more than 20mph without it overheating or popping my nimh packs.- its sheer luck you havent killed your own batts.

    I only rip into people if they insist on... 'not helping themselves'.... with their posts and responses to input/ advice; only so many times you can explain how to do something to someone before you loose your patience and snap at them (see: lukebro )- and only so many times you need to ask about the same problem in the hope of getting the answer you want hear before someone steps up and points out its never gonna happen. You're overgeared and the truck is too heavy for the system to power it at the speed it is geared for- drop down to a 12t pinion and you should see an improvement straight away. Ditch the summit tires for something smaller and lighter and that will make a big difference too, otherwise dont be suprized if you keep getting the same issue with low throttle inout and the straining to reach topspeed/ taking ages to slow down.
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  10. #10
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    point is the guy needs new batteries. nimh just doesnt handle brushless systems. they may for a little while but eventually brushless power will kill them. lipos are cheap these days, not like when first introduced

  11. #11
    RC Turnbuckle Jr.
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    Aye, $25-30 for some 2s ~30c 5000mah *******s or blue lipos/ gens ace- doesnt have to be uber awesome $80 packs..
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  12. #12
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    Seems there is some confusion AOD. The video I posted had nothing to do with what is going on now. What is going on now is not stuttering. I clearly explained this in my initial post. If I punch the throttle in high gear, the truck jerks forward a tiny bit, stalls out completely for a split second (that means the motor stops turning and the truck stops moving), and then it takes off at full speed like normal. This has nothing to do with cogging. That's why I made a new thread about it. However, I think that the batteries are still the issue. It doesn't matter how stupid or "unhelpful to themselves" someone is. Your advice would probably be more accepted if you presented it in a kinder manner. Anyways, I'm sorry. I just can't stand it when people are anything less than kind to other people who intend no harm. For all you or I know, someone doing a thread on a seemingly lame issue could be some 10 year old kid that has no idea what he is doing with his truck (which is an entirely different issue). I will take your advice and go get me some better lipos. Yeah, I meant $80 for two. Which is actually very good but everyone has to watch the finances these days.
    Why can't other people share my opinions?

  13. #13
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    Which is better: ******* or ********* lipos?
    Why can't other people share my opinions?

  14. #14
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    Either is fine- if you get the same spec I doubt you'd tell any difference.

    As for the throttle lurching, that isnt a good sign at all- I'd say its still a battery issue there mainly ( Im assuming you have a 2.4ghz radio to rule that out - if it takes off fine when you roll onto the throttle gently then thats a clear give away. Gearing down to reduce the initial load will still help though, but I'd say my recommendations still stand regardless.

    Treat the summit like a summit ( crawler/ trail truck ) and less like an erevo, emaxx or flux and it will behave a bit better with whatever power system you use ( you know what I say, if you wanted a fast powerful truck to drive on the street then the erevo would have been the best choice, instead of trying to drive the summit like an erevo or turning it into one.. ).
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  15. #15
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    Alright, thanks. Yes, the car does start off fine when I just ease the throttle on. Yeah, the more I think about it the more I am convinced it is a battery issue. I'll grab a couple lipos and see if that fixes it. So is it all good between us now?
    Why can't other people share my opinions?

  16. #16
    RC Turnbuckle Jr.
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    Was it ever truelly not good...



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  17. #17
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    Well Jeez, sorry I never thought of that when you PMed me Larsen. We all could have avoided the bickering, breaking up and making up of this thread, which was no where near the point but I'm certain everyone enjoyed it, lol.

    I would like to add a comment though. Did this stalling condition just occur? or was it there all along? I ask this because if it just occurred a good test would be to cycle your NIMH packs(as long as you have a charger that has a discharge cycle). If it goes back to normal operation after cycling the packs you know without a doubt its the batteries. Although it would not necessarily mean you don't still need LIPO's, because you should be running LIPO's on any brushless system(NIHM packs don't do the brushless systems justice)

    PS. I never told you for a fact that you were not over geared, I quoted the Novak instruction sheet that said the only true test of gearing is temperature.
    http://traxxas.com/forums/showthread.php?536733

  18. #18
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    Fair enough quadiak. However, my system never got hot. The motor would get a little warm to the touch (emphasize "little") and I couldn't feel any heat on the esc heatsinks. Well, it looks like we were all misunderstanding each other. AOD, I love your flame thrower guy. And to answer quadiak question, I don't know if the problem was there all the time because I rarely punch the throttle in high gear. This is because the motor spins so fast that it just spins the slipper clutch (that is when it doesn't stall). The stalling problem I have found is very inconsistent. It doesn't do it all the time. The main time that I was testing this I repeatedly started and stopped about 10 times, and it stalled probably 7/10 times. The other three it just accelerated and spun the slipper clutch as it normally would. And we can all get along now and be friends because I just got a 12t pinion and geared my truck down and it seems better. Not as fast (still faster than stock by a good margin), but has more power and sounds much smoother in high gear. I think I will keep it here. I don't know why I was so stupid as to not try this before.
    Why can't other people share my opinions?

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