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Whats going on with my e-LST build?? clunky start up and light beeping....

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Old 01-31-2015, 03:01 PM
  #1
mattmatt001
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Default Whats going on with my e-LST build?? clunky start up and light beeping....

So im progressing with the build of my E-lst ... and I noticed a clunky noise when accelerating. I also get a red light and light beeping as Im coming out of the neutral range.... is this normal?

https://www.youtube.com/watch?v=AK3cbOv7kjE&feature=youtu.be

Is my mesh tight enough?

https://drive.google.com/file/d/0B9h...ew?usp=sharing
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Old 01-31-2015, 03:39 PM
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All looks normal to me. The "clunky" noise when accelerating is partly the slack in the drivetrain. The fact that sensorless brushless systems start abruptly makes this more noticeable. You're also giving very light throttle inputs which worsens the cogging and actually makes the clunky noises worse since the the motor is not spinning a constant rpm and is instead speeding up and slowing down causing more noise from the slack in the drivetrain. Remember the LST has an all metal gears transmission so there's going to be gear noise. I do recommend having a look at your diffs and reshimming them if necessary. Brushless has lots of instant torque, slack in the diffs will cause failure sooner or later. From what I can see and hear in the video your pinion/spur mesh is fine.

The beeping like noise is actually from the motor and is perfectly normal. It's just a characteristic of brushless motors, particularly bigger 1/8 size ones.

As for the LED on the esc, I'd look at the manual for your esc. On most esc's the LED will indicate throttle position by being one solid color while neutral, then when throttle or reverse is applied they will switch color and start blinking. The more throttle (or reverse) applied the faster the blinking until full throttle (or reverse) is achieved they will be a solid color. Castle esc's are Amber for neutral, green for throttle and red for reverse. Castle will blink green for partial throttle and be solid green for full throttle, same for reverse except in red. As I said check your esc's manual to be sure but this is common practice to indicate throttle position, although the colors may vary between manufacturers.

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Old 01-31-2015, 03:53 PM
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Thank you for that, maes me feel better! This set up is sensored (so it says??), The cable seems to come out of the esc fairly easily though :-/
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Old 01-31-2015, 04:03 PM
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I just clicked the link with the picture of your mesh. That does appear to be a bit on the loose side. Before you adjust it, hold the pinion still and rock the spur gear back and forth. That play you feel is desirable, you just want the least amount of play possible, if there's no play the mesh is too tight. Make sense? Also be sure to check the mesh all the way around the spur as they're not always perfectly round.

I had the Losi kit on one of my LST's and I could not get the mesh tight enough with 25/63 gearing without modding some things. The Losi mount hits the mounting ear of the transmission, if you take off the spur gear you can see it hit. I used a Dremel with a sanding drum to take a little off the corner of the mounting ear and was able to get the mesh just right.

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Old 01-31-2015, 04:08 PM
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Quote:
Originally Posted by mattmatt001 View Post
Thank you for that, maes me feel better! This set up is sensored (so it says??), The cable seems to come out of the esc fairly easily though :-/
The startup of your motor doesn't seem as smooth as some sensored setups I've seen, but I've only seen Tekin. Again I'd check your esc manual, make sure you don't have to enable sensored mode and see if you can somehow get the cable to stay put.
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Old 01-31-2015, 04:28 PM
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I also have the TDR mount, maybe i should just switch it over! cant find any info on enabling/disabling the sensored mode maybe its the wire.
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Old 01-31-2015, 04:40 PM
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Just for a little context here is the car whilst on the ground.....

http://youtu.be/2d59RRB7_lY
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Old 01-31-2015, 04:43 PM
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I was going to mention getting rid of the Losi tray since you're just using it for an esc shelf with the other battery tray mounted up front. If you have the TDR mount get rid of that Losi junk. It doesn't even give you proper mesh with its intended gearing. The Losi motor mount doesn't contact the can of the motor so it actually holds heat in, my motor temp went down 15F easy just by switching to an open mount like the TDR.

Your esc should fit in the space behind the motor and can be double sided taped there. I made a shelf similar to the one TDR sells out of a sheet of Lexan I bought at Home Depot. I actually made two and used the other to mount my Traxxas receiver box up front. You'll likely need a servo extension to mount your reciever up front with the esc out back. That's the most common layout for these trucks but you're free to come up with your own.

Edit: That does sound much worse being on the ground. But what I said about the cogging still holds true. Your mesh is on the loose side but it's not skipping, the motor is cogging due to the low throttle input. Sensored setups generally don't cog like that though and are much smoother on startup since the esc knows the motor's position and isn't using a generic startup algorithm like a sensorless setup. Let me have a look at the Hobbywing manual and see if I can find anything to help.

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Old 01-31-2015, 04:46 PM
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This couldnt be something called "cogging" could it? sound like an RC funeral if it is
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Old 01-31-2015, 04:46 PM
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tdr mount is going on as we speak!
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Old 01-31-2015, 04:52 PM
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Edited my post above. But yes that's cogging, something genrally reserved for sensorless setups.
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Old 01-31-2015, 06:56 PM
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Bad times! Is it terminal?
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Old 02-01-2015, 11:16 PM
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Sensorless setups cog because the esc doesn't know the motors position from a stop or at low speeds. The motor needs to spin a certain speed for the esc to read the EMF coming back through the motor wires to know the motor's position. From a stop or below this speed the esc uses a preprogrammed startup algorithm. If the motor can't reach that speed where the esc can read the back EMF by the end of the algorithm the esc starts the algorithm again and we see that as cogging. Cogging doesn't sound very good to the ear but it's not actually hurting anything.

Sensored setups know the motors position at all times so the esc can fire the right motor phases for a smooth startup instead of just firing an algorithm that'll get the motor spinning but not as smoothly. Right now it looks like your running in sensorless mode instead of sensored. I don't have much experience with sensored setups except for my Tekin RX8 but it's a lot smoother than that and I'd imagine yours should be too. Check the pins on the esc and the wire to see if any got bent. Unplug the battery, reconnect the sensor wire and try it again but hold the sensor wire into the esc if you can. It would be nice if the esc let you know when it was in sensored mode with an led or something but at least it automatically switches to sensored when the sensor wire is disconnected.

I believe the manual showed a way to reset the esc. I'd try pluggin in the sensor wire and resetting the esc too. Other than that contact Honbywing and see what they say and/or can do for you as far as a replacement. Electronics do fail and ones with manufacturing defects usually fail in the first few minutes.

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Old 02-02-2015, 12:43 PM
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Wow thank you! your level of knowledge and readiness to share it is truly astounding! Im wondering if the battery is low and the esc isnt picking it up, the sensor wire was pretty beat up so ive bought a new one! once ive charged ill do a reset and add the new wire ( I assume its that as it makes no difference if its plugged in or not!) I want to get rid on the stock bulky pinion and have a 64t delrin spur from Jay. the plan is to bash and ive read a smaller pinion is good for taking strain off the motor (2250kv) do you think 22t is about right? an on-line calculator put me on to 22t.

Thank you again for all your help, fingers crossed it was just the wire, it runs quite well at slightly higher revs
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Old 02-02-2015, 04:38 PM
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No problem, glad I can help even if the problem isn't solved.

Gearing helps determine the load on the motor, along with weight, the surface being run on, etc. Smaller pinion means less top speed and less load. Bigger spur means less top speed and less load. Running the truck is the only sure fire way to know if the gearing is right but I can give you a safe starting point and get you close. What voltage (how many cells) is the Lipo you're going to run? I remember you were unsure in the other thread.
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Old 02-03-2015, 10:34 AM
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Its a 4s lipo on a 2250kv xerun with a 150a esc, the truck has hobao pirate wheels will this affect performace? as I say uts currently stock 25/63 I have a delrin 64t to hand if that helps?
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Old 02-03-2015, 01:06 PM
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weird just plugged in a fresh lipo and it start going backwards?????
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Old 02-03-2015, 04:03 PM
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The plot thickens.... I have taken it apart... again! In an effort to diagnose... The video shows it rolling without motor and esc and then the motor and esc alone. when I give it the first go it doesnt spin and the orange wire twitches like a dogs leg! then it seems smooth (ish) still an esc issue?

https://www.youtube.com/watch?v=cExvIjoQzKk
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Old 02-03-2015, 07:02 PM
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First, your video is showing that it's private so I can't view it. The motor rotation reversed? The only way that should happen is if you switched two motor wires (can't do that in sensored only sensorless), changed the motor rotation in the esc settings, or reversed the throttle channel on the transmitter.

Second, did you install the transmission years that were included in the Losi kit? I almost forgot about them and they do raise top speed which isn't always the best thing but in this case should be fine. Those Ofna/Hobao tires are actually shorter in diameter than the stock LST tires lowering top speed a bit. You shouldn't have a problem with 25/63, even with the stock LST tires and the Losi conversion kit gears installed in the trans the top speed should be low enough for the motor to handle.
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Old 02-04-2015, 01:17 PM
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Sorry video is now available! doh! Just opened the tranny and as its a FOC its hard to tell but they look like the stock bits in there
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Old 02-05-2015, 10:22 AM
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videos help but it's still not as good as being able to touch and see it first hand. Your chassis seems fine. As I said, the all metal gears in the trans are going to make noise.

Motor and esc. The motor isn't secured to anything and the Orange wire has the least tension on it that's why it moves around. I know you're probably giving it light throttle which tends to induce cogging but without any load on the motor it should spin up without issue. It should spin up abruptly because it's in sensorless mode (no sensor wire in the video) but it should spin up. The problem is it doesn't and actually cogs with no load on it. There's something wrong here.

I recommend making sure the end points on your transmitter are maxed out for both throttle and brake, set the exponential to 100%, make sure the thottle trim is centered and then recalibrate the esc to the radio. If that doesn't help the other possibility is a weak solder joint or weak connection in the motor wires. I had a brushless system act similar and one of the bullet connectors was barely soldered in. You'd have to remove the shrink wrap on the connectors and resolder them to the wires. This may not solve the problem though and you might be better off contacting Hobbywing or the dealer you got it from before doing something like soldering on it as that might void any warrantee you might have.
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Old 02-07-2015, 07:50 AM
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Thank you again for the information, all the connections seem to be OK... expect the sensor wire! looks a bit manky at the esc and and doesnt stay in the port. I need a new transmitter anyway so will buy one and set it up fresh alongside a new sensor wire!

In the instance this fixes it.....can anyone tell me if there is benefit to a 24t/64t set up on my LST conversion? I have a delrin 64t spur which I would like to use so thought I should drop the pinion to 24t?? I am going to use it for bashing mainly
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Old 02-07-2015, 10:16 AM
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Well I hope you solve the problem.

I and others put lots of power through the stock plastic 63T spur without issue. The Delrin might be stronger and if you have it might as well use it. The larger the spur gear the slower you will go, you'll lose 1-2mph with the 64t vs the 63t. There's no reason to go with a smaller pinion when putting on the larger spur. Keep it the same size or go up a tooth so you don't lose any top speed. A 26t pinion with 64t spur will actually be slightly faster than 25/63.
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