azalner

My Feedback: (8)

I bought two Traxxas Stampede trucks for my grandson. These came with brushed motors and NiMH battery packs. Within a year the ESC’s failed and I decided to upgrade to brushless motors and Lipo’s.

I replaced the ESC’s with the following:
http://www.hobbyking.com/hobbyking/store/_13445_HobbyKing_Brushless_Car_ESC_45A_w_Reverse.h tml?strSearch=hk-45a



The motors were replaced with:
http://www.hobbyking.com/hobbyking/store/_9822_TP540_11_5T_3350kv_Brushless_R_C_Car_Motor_w _sensor.html




The batteries were replaced with:
http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html



Initially everything seemed fine. The cars had plenty of zip and the boy could do wheelies to his heart’s content. Also the larger capacity batteries allowed him to play with his trucks for longer than 15 minutes. The only problem was that the cars would not run in reverse – they would just stutter. But the boy didn’t care he liked to go full tilt forward anyway.

But now both cars have developed the same problem. They will not go in forward or reverse. They just sit there and stutter. So the question is: What has failed? Is it the ESC or the motor or both? Any recommendations for replacements?

collector1231

My Feedback: (1)

I'm pointing my finger at the ESC. Go to your local hobby shop, and ask if they can test the ESC and motor for you.

Also, try slowly accellerating it instead of gunning the remote.

azalner

My Feedback: (8)

OK, I tested the motors by measuring resistance across the phases. Here are results:
A-B .55 ohms
A-C open
B-C open

So obviously one of the phases is burned out. The question is why? Overheating? Drawing too much current?
The ESC is supposed to have over-current protection; the motor is rated for 220 watts which figures to 30 amps for a 2S battery. So it's possible that I smoked the motor but the ESC is still OK. I will check the ESC later on today using my servo checker.

What would make this motor draw too much current? Gearing?

jester_s1

When ESC's fail, they usually just won't do anything. My experience is with airplane brushless systems, but they work pretty much the same. Now you're finding out why HobbyKing stuff costs so much less than other vendors. Some of their stuff is pretty good, but some of it is total junk. Either way, they have no warranty support so you're going to be paying for replacements. One thing I noticed is that the motor has sensors, but the ESC is a sensorless ESC. I couldn't tell you if that could cause your issue, but it's something to research.

As for your questions, you are right- too tall a gear would make it draw too much current.

collector1231

My Feedback: (1)

The ESC is 35 amps. Thats pretty low. At least a 40 amp ESC is reccomended for 2S. BTW, what did you test, the ESC or the motor?

azalner

My Feedback: (8)

I tested the motor and determined it was bad because one of the windings was open.

I checked the ESC with another brushless motor (one of my multi-copter outrunners) and it checks out OK.

The motor that went bad is rated at 220 watts and it was made by TowerPro. That makes it a POS in my opinion, even for a toy truck. I will be replacing it with a Turnigy TrackStar 3300kv, 12T and upgrading the ESC to a 60 amp unit.

collector1231

My Feedback: (1)

I wouldn't replace it with another turnigy. I'd replace it with a brand name motor, so it has a less chance of failing.

Motor; http://www.amainhobbies.com/product_...ess-Motor-135T
ESC; http://www.rcmart.com/speed-passion-...Path=1560_1021

azalner

My Feedback: (8)

The one that failed wasn't a Turnigy - it was a TowerPro

The reason it failed was not the name brand - it was undersized.

phmaximus

yep defiantly. Over gearing or any kind of load will draw more current. The higher the load, the more amps the motor will draw....
and as u know the higher the current draw the hotter things get.

Ive found kids have a uncanny ability to overload RC cars. I always recommend low gearing for kids.....
why u ask... Well it's because of all there starting, stoping, getting it stuck, burn outs, not stoping when hitting something, sitting on it, holding it, oh mate the list goes on. My kids have done it all...but yeah, I highly reccomend low gearing lol

a good way to check for excessive gearing or overloading is every now and then, when its running check the ESC Temp and motor temp.

something like a Yeah Racing tornado 30mm fan and adapter is a cheats way to push the ESC to the limit, because every last amp u can draw with out overheating problems will give u more power (A x V)... This also apples to the motor with a heat sink+fan

This problary didn't help much with the current problem but might help down the track?

azalner

My Feedback: (8)

Thanks mate! Good things to keep in mind.

phmaximus

hey just reading that there is some doubt about using smaller motos.... there is not a hole lot different from a slash to a stampede. only wheels are the main difference and generally gearing reflects this.

Ive got a Slash thats been running a old version 1 YeahRacing (rebadged hobbywing) 35a ESC and a 3900kv 380 core motor running 23/87 gears for around 3 years in the slash and over 6 months in a Tamiya Baja king. Its been through hell and back in that time, even on a 3s lipo and still going strong.

Only problems
The stock fan lasted about 6 months running on the built in BEC intill it got very wet one day. easily replaced and upgraded with 2s Tornado 30mm fan and adapter
One of the motor wires needed re soldering... my fault, a cable tie nearly severed the wire. easy fix the, the solder points are outside the ESC housing

I highly recommend the Hobby wing Ezrun ESC's. The 35a ESC is one powerful little hot box. and the 60a is even better...
just to give u a idea, keep in mind doing a burnout increases current draw. But this video I made demonstrates the power from these. im running a 35a ESC but with a 60a ESC and fan upgrade it could possible do a never ending burnout with out over heating..... So i would say the 60a is slightly overkill but the 35a is definatly up to the job. after all its rated at 190a burst.... as u can see in the video even doing a burnout it would be lucky to draw 70a

http://www.youtube.com/watch?v=xbQcM_qJ5C4

phmaximus

So yeah I would look into a Hobbywing 3300kv or 3900vk 380 cored 540 size motor for ur current ESC.

and here is how I got a heat sink and Fan to fit those gearboxes... all u need is a hack saw blade, cable tie and some Computer thermal past... remember u can always upgrade the fan to a 2s lipo compatible fan down the track.

azalner

My Feedback: (8)

You convinced me. I just ordered the

07E-HobbyWing-13T-3650-M-Motor

Beats waiting for the slow boat from China and shipping is very reasonable.