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Model Forum / Radio Controlled / Land Models / December 2003My first electric RC Car... and my first problem with it!
Hey guys, After surfing the web and gathering masses of info, I finally made up my mind and bought and HPI Sprint RTR two weeks ago *crowd goes wild* :-) The guy at my local hobbie shop told me it was really easy to assemble (RTR, so I just needed to install the ESC + heat sinks, centre the servo, glue the tires and attach the wiring correctly). Piece of cake, it seemed, even for me :-) Everything went really well, no problems whatsoever... until I saw a paragraph in the instruction manual of the ESC (brand: LRP Runner Plus Reverse) wich mentionned something about 'Schottky (?) Diodes' (which could be needed in some cases) and soldering some little, metal pin-like things to the motor. It all sounded like Chinese to me, but since the guy at the hobbie shop had specifically told me I didn't need to solder anything for assembling the car, I 'finished' it without worrying too much about the paragraph I didn't really understand... This weekend I took the car to a parking lot to try it out, happy as a litlle puppy. :-) The first run went great. Very slow and careful, but accurate ;-) I even took a few cones with me so I could start praticing controlling the car, and playing with the control-settings on the transmitter (so many new buttons and so much to learn!) After the first battery went down, I took a break for about 15m, checked the car (screws still tight? everything still in place?), and then I placed the second battery pack. After just a few minutes of somewhat faster driving (full throttle for the first time + using brake function now & then) I suddenly noticed the car started to behave rather strangely. After braking and hitting the reverse, the car wouldn't take off anymore, all of a sudden... But when I released the throttle stick on the transmitter and tried again, everything worked again. I decided to take the body off the car to see if something had come out of place while driving, but no... Until I put it back on the ground for another spin (without the body this time) & saw sparks coming out of the engine when braking hard, or going to reverse!!! Not too healthy for the engine I guess, so I stopped driving it right away. At home I checked it again, but I can't see anything that isn't where (I think) it's supposed to be... :-( I just hope I didn't allready ruin the engine... So now I'll have to wait 'till saturday before I can go to my local shop (just when it's dry outside => how cruel!), to check out what I've done wrong. Unless any of the experts here can help me out with this one of course? ;-) I just want to know what went wrong, and what I need to do to fix it of course... Massive thanks to anyone who gives it a shot! Nossy. PS: I posted some pictures of my car on alt.binaries.radio-control, so if you guys want to take a look... > I just hope I didn't allready ruin the > engine... I'm assuming you have a motor (electric), not an engine (nitro fueled). If the motor is throwing sparks here's some suggestions: 1. were you running the car somewhere where lots of grit could have gotten into the motor can? 2. Is the pinion smashed against the spur...there should be some play. 3. Did it go thru water? I have had the same symptoms you mention after running in a construction site where there was lots of the dirt that was in little balls and dried. The little clumps were small enough to get jammed inbetween the armature and the magnets in the motor can. It caused lots of sparks then the motor would glitch. Take the motor off, try spinning the pinion with your hand. It should spin freely with no crunching sounds. Use some electric motor spray on it. Spray it liberally inside the holes of the motor and all over the brushes. Let it dry. Try spinning the pinion with your hand. It should spin freely with no crunching sounds. Remount the motor, position the pinion against the spur correctly, and try it again. what motor do you have installed? Was it new? > Take the motor off, try spinning the pinion with your hand. It should > spin freely with no crunching sounds. Use some electric motor spray on [quoted text clipped - 4 lines] > > what motor do you have installed? Was it new? Just to add to that excellent advice, *some* sparking (particularly under high braking or reverse current) is normal, although it should be no more than a brief flash. Our motors - particularly modifieds (anything under 27 turns) - run very close to the edge, and also have the timing set up to work well when running forwards. Asking them to produce torque in the opposite direction will inevitably cause some arcing at the brushes. Having said that, the 'sticky throttle' does sound like there's some sort of problem... :-( Good luck, Jonny waiting for brushless to become race-legal... The 'sticking throttle' is probably a lockout feature that prevents jamming from forward to reverse (and blowing gears/trannies/fuses) The description of the Runner on associateds website sucked, but i imagine most escs have that now. My Futabas do. It kinda waits till the car is stopped until changing direction. as for the sparks, most motors make some degree of arcing across the commutator. If it aint shooting sparks out of the vent hole, i wouldnt worry about it. > > Take the motor off, try spinning the pinion with your hand. It should > > spin freely with no crunching sounds. Use some electric motor spray on [quoted text clipped - 20 lines] > Jonny > waiting for brushless to become race-legal... >The 'sticking throttle' is probably a lockout feature that prevents jamming from forward >to reverse (and blowing gears/trannies/fuses) >The description of the Runner on associateds website sucked, but i imagine most escs have >that now. My Futabas do. It kinda waits till the car is stopped until changing direction. >as for the sparks, most motors make some degree of arcing across the commutator. If it >aint shooting sparks out of the vent hole, i wouldnt worry about it. Agreed, I was also thinking that the ESC could have a lockout function that would prevent a lot of throttle application from damaging the drivetrain...also, I agree that at least to some degree, those sparks are normal, we call that arcing, & it does appear the most when using the brakes or reverse(but there's almost ALWAYS some bits of arcing as the motor runs).....:) > > I just hope I didn't allready ruin the > > engine... > > I'm assuming you have a motor (electric), not an engine (nitro fueled). It's an electric motor allright. Sorry for the misunderstanding, must be my basic English... > If the motor is throwing sparks here's some suggestions: > > 1. were you running the car somewhere where lots of grit could have > gotten into the motor can? It was a normal asphalt (tarmac? => don't know the proper English term) road, and there was hardly any gravel on the part of the road I used for training... > 2. Is the pinion smashed against the spur...there should be some play. > > 3. Did it go thru water? No, I'm certain about that. > I have had the same symptoms you mention after running in a construction > site where there was lots of the dirt that was in little balls and [quoted text clipped - 8 lines] > spin freely with no crunching sounds. Remount the motor, position the > pinion against the spur correctly, and try it again. Thanks for the suggestion! I'll try that out as soon as I can & let u guys know something. > what motor do you have installed? Was it new? It's the motor that was allready installed in the car (servo was also allready there, just the ESC needed to be installed and some other little things). I believe it's a Saturn 20T, and it's new. I took it out for a spin just 2 times, so I doubt it has anything to do with that... I was even more carefull with it than with a real motorcycle or car, can you imagine :-) NEVER USE 'Schottky Diodes' on a ESC with a REVERSE !!!!! on reverse you are shorting your esc. (breaking is ok) . TM > Hey guys, > [quoted text clipped - 47 lines] > PS: I posted some pictures of my car on alt.binaries.radio-control, so if > you guys want to take a look... > paragraph in the instruction manual of the ESC (brand: LRP Runner > Plus Reverse) wich mentionned something about 'Schottky (?) Diodes' > (which could Don't worry about it. Schottky diodes are for forward-only ESCs; you never use a Schottky diode with a reversible ESC. > be needed in some cases) and soldering some little, metal pin-like things to > the motor. It all sounded like Chinese to me, but since the guy at the Those are motor capacitors. They damp the noise from the motor so it doesn't interfere with the radio. Without them, you might get glitching or weird control problems, particularly at long range. But it won't hurt anything. > I put it back on the ground for another spin (without the body this time) & > saw sparks coming out of the engine when braking hard, or going to > reverse!!! Braking and going in reverse often cause sparking around the motor brushes, inside the motor. However, you should never see sparks flying out of the motor. If you see that, then something is wrong with motor. My guess is that a bit of gravel got lodged in the motor can, or one of the motor brushes is damaged. Your hobby shop can check the motor for you. If you ask nicely, they'll probably show you how to dissassemble the motor and check the insides yourself. It's not really complicated. Here are some guides for you: http://www.hobbytalk.com/modules.php?op=modload&name=Sections&file=index&req=vie warticle&artid=31 http://www.hobbytalk.com/modules.php?op=modload&name=Sections&file=index&req=vie warticle&artid=32 Rick R. > Your hobby shop can check the motor for you. If you ask nicely, > they'll probably show you how to dissassemble the motor and check the > insides yourself. It's not really complicated. > > Here are some guides for you: http://www.hobbytalk.com/modules.php?op=modload&name=Sections&file=index&req=vie warticle&artid=31 http://www.hobbytalk.com/modules.php?op=modload&name=Sections&file=index&req=vie warticle&artid=32 > Rick R. Thanks! There really is a lot of info on that site that's mighty interesting for a newbie like me... I allready looked for this sort of info on the internet but I didn't found these pages. This should clear up a few things :-) Saturday, I'm going to the hobby shop to ask the guys over there to give me a hand with the motor. Don't want to ruin my new car on my own... ;-) > Reverse) wich mentionned something about 'Schottky (?) Diodes' (which could > be needed in some cases) and soldering some little, metal pin-like things to > the motor. It all sounded like Chinese to me, but since the guy at the Capacitors? If so, they can reduce radio interence from the motor. > After braking and hitting the reverse, the car wouldn't take off anymore, > all of a sudden... But when I released the throttle stick on the transmitter [quoted text clipped - 3 lines] > saw sparks coming out of the engine when braking hard, or going to > reverse!!! Sparks can occur, and are not necessarily a sign of problems.  SignatureL.V.X., brother mouse http://www.mousetrap.net/otr/ Old Time Radio trades http://makeashorterlink.com/?K16312E06 CBS Radio Mystery Theater database http://greyhound.mousetrap.net/altus/ retired racing dog |
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