Help diagnosing motor/esc problem?
 

I suddenly have a problem with my Losi 22T (1.0). I bought it RTR on Ebay. It has an Orion 6.5T motor and a Trackstar Turbo 120A ESC (v1).


It was glitching on occasion, where if I landed a jump hard, sometimes it wouldn't go forwards until I quick popped it in reverse. Then it ran fine. It happened a few times after landing a big jump.

Just now it started to really act up. I thought it went into LVC, but the battery still had 4v/cell. I got a new pack, and the wheels spun up. But not smooth, sounded almost like a gear clicking or stripped. But all the gears seemed fine.

So I tried to run it down the straight, and the motor was pulsing badly, rapidly on/off. It would kick up a tiny rooster tail ever 6-12", and rolled inbetween.

I pulled the motor out to inspect, and it seemed to run smooth at low rpm and no load. (Not a sensor wire issue?) But then I found a dead spot, where it wouldn't start spinning if it was held in that position.


So question is, does this tell me if it is the motor or ESC? Or both? Is there a way to diagnose the problem without already having a spare motor? I'm hoping it is the ESC...

Could be a sensor issue, usually it is the hall-effect on the motor itself. If you try it with the sensor wire unplugged is the behavior different? It will not be smooth but if the sensor is the problem then the dead-spot may be eliminated.

Taking a guess at it, the esc is acting up, but depends on how much you ran this set up, and how hot you got the motor, for me personally I only run down to a 10.5 motor, as I tend to get carried away with the power and speed of the bigger motors and tend to over heat them, by just screwing around either on the track or in front of the house, but honestly the only way to determine which one is at fault is to change one and/or the other so if you have a spare motor, change it same goes for the esc

By chance have you tried to recalibrate the esc??

Read manual. RTR has one. Try rebinding the TX & RX. Then Recalibrate your ESC. Good luck!!!

You got my hopes up...but it turns out this ESC is sensored only. No joy.


I ordered a new hall sensor. I was hoping to race this weekend, so hopefully Horizon comes through on their 2 day shipping...it appears they use Fedex 2 day, which should deliver on Saturday... Fingers crossed!

Yeah, I've re-calibrated several times. Funny story...my radio was set to 70/30 for one model, but 50/50 on this losi by accident. So every time I forgot to switch models on my radio before turning on the car, it'd run full throttle in reverse...and it doesn't shut off when I kill my radio... So yeah, I've re-calibrated it a few times. :) It took me awhile to figure out what was wrong.

I've only had the truck for a couple of days, and have run 3-4 packs through it. The original owner said he ran it 10 min total.

the motor has been running stone cold...it feels slightly warmer than body temperature. I rarely get to full throttle with it, because my track is natural black dirt and bumpy.

#notatraxxas :)

It's a used truck, a kit built by someone else, who selected the electronics. Technically it's an ARTR? 'Cause I am using my own radio and receiver...whatever...it's still not working!

Your symptoms are very similar to issues I've had with SkyRC branded ESC's in the past. I used to run them in all my cars and they did great (when I was mostly racing on-road), a little over a year ago the on-road club suspended their program indefinitely and I've been running off-road exclusively where pretty much every SkyRC ESC I owned had started to act up, typically from hard landings off big jumps. It was as if the ESC was browning out, I would lose both steering and throttle so I knew it was ESC related. Things got worse when it would land from a big jump and then steering would lock straight and the car would lunge @WOT for a split second. It seemed manageable because it happened infrequently enough until one day my eBug slammed into a turn marshals shin, left a huge bruise that took weeks to heal, man I still feel bad about it :(

So that was the last time I used SkyRC in any of my 1/8 cars. Flash forward a few months and eventually my 1/10 cars would start acting up on the smaller 1/10 track too.. SMH

Really breaks my heart, because the SkyRC ESC's treated me very well for years of on-road racing (with no jumps) but they just can't handle impacts for some reason over time and I have since switched to HobbyWing across the board for the 8+ classes I run. Knock on wood, I haven't had a single issue with HobbyWing other than accidentally leaving my battery plugged in for a couple weeks and learned the hard way that the XR8 has a parasitic drain that killed a 4S pack.

Not sure which specific TrackStar ESC you have without a link, but I've seen several that are rebranded from SkyRC and if that's the case, then I'm fairly certain you're running into the same quality issues I did and would consider switching brands as well.

Trackstar is kinda like OFNA, they don't manufacture anything, they will bid out to OEM's to rebrand products with the TrackStar label on them... if you want to go cheap, then I would recommend their Aeolian rebranded ESC's, those have never failed me.

Good Luck!

Thanks. My ESC looks similar to the SkyRC units, but I'm not seeing an exact match. Here's a photo of the unit: http://static.weloveshopping.com/sho...a/11746545.jpg

It does seem that the hall sensor is going bad. Did your ESCs damage a hall sensor? There is a clear dead spot. When I hold the rotor in a certain position and hit the throttle, nothing happens. The ESC seems to shut down. The motor hums for a second like it is trying to start, and then it just stops like it got turned off...

I ordered a sensor, but I don't want to damage it as well by connecting it to a bad ESC. It sounds like I won't be racing it this weekend.



I bought the used truck because I have trouble buying cheap electronics. Initially I wanted to buy the new Losi 22T 3.0, and I would have gone straight to the Tekin RSX for my ESC. I can't help myself! But I quickly realized that by the time I had it built, it was going to be an $800 truck, which seemed awful expensive for a small and simple 2wd. For comparison, $900 buys me a bigger and more complex tekno sct410.3 (with RX8 and e-buggy motor! :) ), and $1,200 would buy me a Mugen truggy.

So I bought this one on Ebay, avoiding the temptation to buy high end electronics. But now I guess I have to face my demons after all! :)

Not sure who the OEM is for that particular ESC, but it doesn't really look like a SkyRc to me, if anything the switch kinda looks like a HobbyWing, or some variant of a HobbyWing clone. I have had pretty good luck with their X-Car series ESC's, they used to be rebranded through Brushless Hobbies and are also HobbyWing compatible in terms of the programming cards. I would ask around the track to see if someone has a HW programming card to test on your ESC?

I would also consider investing in a Hall Sensor tester too:

+ YouTube Video

Another angle, I have had receivers go bad especially the antenna. Make sure there is no antenna damage. Also I had a flysky transmitter go bad causing my car to randomly go crazy and glitch. That was not easy to diagnose.

That's a good point, I used to race with a KO Propo EX-2 and that system would periodically glitch with delayed input to both steering and throttle, I simply had to re calibrate the Tx to every Rx in my collection, it was kind of a pain when having to do this for 8+ Rx's and it became impractical doing this once every 4-5 race days so I gave up on the brand :( I've had similar issues with other brands of radios too that would often lose their bind sequence and had to re-pair the Rx with the Tx's, my FlySky Rx got so bad I had to pair it practically every day before I gave up on that brand, I replaced a handful of Rx's only for each replacement to progressively get worse over time... live and learn I suppose :)

The Trackstar ESC's are not made by SkyRC or Hobbywing just FYI.
Even thought he ESC has a sensor port is should still be able to run a non-sensored motor, although there are now some motors that can do both the general rule is a sensored motor needs a sensored ESC but a sensored ESC can run either. If not a melt-down of the motor or ESC the most common issue we see by far is a bad sensor board in a motor. You can test them with a motor analyzer or if you by any chance have access to an oscilloscope, but for the cost it's usually easiest to diagnose by swapping parts.

I will test that. The receiver I have is used...included with my Ebay radio (4pks). And I do have another one.

Part of the antenna wire did look a little chewed up, but I didn't think much about it.

I have had the problem of re-pairing pretty often. I thought maybe it was a narrow neutral width setting messing with the receiver?

I will check and report back!




Later:

It may be one issue I was experiencing, but the pulsing remains. The antenna was slightly damanged and kinked, which could contribute. I put some heat shrink on the area, and now it doesn't kink.

But it really does seem to be related to the rotor position. But I guess I won't know until I receive the new hall sensor.