MambaMax ESC quirk - Page 5 - RC-Monster Forums

coolhandcountry · 12.02.2006, 06:36 PM

That could explain alot about how fair a spark will jump on a automobile.
I think at 30,000v/cm would free a esc if it got high enough to jump a .5cm.

Serum · 12.02.2006, 06:38 PM

Wires normally jump up and down, from side to side..

I would not run my bl controller with naked wires.

crazyjr · 12.02.2006, 11:07 PM

just a thought, i have run both of mine in the last two days and have seen absolutely no problems, Except for the cog from rolling reverse to foreward, which i believe is a condition of sensorless, My Novak's never had that cog

BrianG · 12.02.2006, 11:18 PM

Quote:

Originally Posted by Serum

Wires normally jump up and down, from side to side..

I would not run my bl controller with naked wires.

Lol, I would hope not! What I think he meant (and correct if I am wrong) is that if you don't have the heatshrink totally covering the connectors (like a 0.5mm sliver of the connector showing) the feedback signal could arc across the connections.

crazyjr: The cogg from reverse to forward doesn't happen with my Quark though. That's why I thought it was an ESC firmware bug. Speaking of Quark; my 125B has a ferrite core covering the power wires. I wonder if something like this would help if done to the MM? The ferrite is supposed to inhibit RF noise from entering the power wire. The Quark also has a ferrite core on the throttle wire as well, presumably for the same reason. Just gotta be careful it doesn't slide along the power wires and short out on the circuit board.

I still think it's a software/firmware issue...

MetalMan · 12.03.2006, 01:37 AM

Quote:

Originally Posted by BrianG

According to Wikipedia, it takes about 30,000v/cm to arc across air. I don't know if the induced feedback signals can spike high enough to get to that point.

Interesting though.

That's odd... My dad has an old transformer that takes 120v AC and transforms it to 15,000v AC (it's basically a ~40-50lb chunk of copper). We have gotten it to arc at up to 2cm in normal air. I wonder if there's some sort of "special" air that the 30,000v/cm came from :005:.

BrianG · 12.03.2006, 01:52 AM

There are several factors that could attribute to the insonsistency you cited:

1: Moisture content in the air will make a difference. More moisture lowers the air resistance so it will arc easier so the electrodes can be further apart.

2: A transformer's output voltage rating is the value when pulling a certain amount of current. If you add a heavier load, the secondary voltage will drop. Pull less than the rating and the voltage will increase. Perfect example are those "wall warts". Ever measure a "9v" supply with no load? It's more like 12-15v. Once you load it to it's rated current, the output drops to near 9v. An exception to this is if there is a built-in regulator of course.

3: A transformers output voltage depends on the input voltage and the turns ratio. For instance; if a transformer is rated to put out 15,000v when a 110v input is applied, that is a 136.36:1 ratio. If the primary is at 120v, the secondary is actually over 16,300v.

Add all these variables and it could make a substantial difference. I'm not saying that Wikipedia is absolutely correct, but it does sound fairly close from my electronics classes oh so many years ago. :)

Serum · 12.03.2006, 03:18 AM

And did it start sparking at two cm or did you need to hold the wires closer to get the spark started?

MetalMan · 12.03.2006, 10:17 AM

Sometimes it would arc at 2cm, but other times it would only happen by starting with the wires (electrodes?) closer together.

BrianG, good points!

phildogg · 12.03.2006, 07:35 PM

Quote:

Originally Posted by Finnster

I've had that occational glitch, like a momentary brake stab. Init thought it was a Rx problem, and started moving things around. Went away a bit w/ an FM and Rx pack, but it happens every now and then (unfortuantely after I nail the throotle and get going then, whack, then back to accel.

:032:

this is the exact same prob I'm having also.. running hard then a brake stab,next thing I know its on the lid sliding..
phil

coolhandcountry · 12.03.2006, 07:56 PM

I heard some one had a problem like this with a bk. It was a bad glitch.

Finnster · 04:28 PM

Found this on the castle website in FAQ, perhaps this may help:

Quote:

2. When I get to full throttle, my ESC cuts power to the motor. I have to throttle off then back on to get the motor to start, but it cuts off again at full throttle. Why is that?
The most likely cause of this problem is a lithium polymer battery pack that is not capable of providing the current the motor, gear ratio, and propeller are asking for. Normally the voltage curve for lipo batteries is almost flat, but when overdrawn their voltage will fall below the cut off point before the battery is discharged completely. The solution for this situation is either a higher gear ratio or a smaller prop, which lowers the current draw of the system. Or, if the performance is not wished to be lost, a higher Mah, or more capable brand of lipo pack can be used.

Another less likely cause for premature LVCO is too small or too high a resistance plug between the battery and the ESC. Also make sure the wires on the battery pack are at least the same size as on the ESC.

If the battery pack is up to the task, and the wires and plugs are sized correctly, it is possible that a sudden motor cut off, with the ability to restart by going to the off throttle position, could be caused by the over current protection on that particular controller being too sensitive.

What got me wondering about this is philldogg's reply where he is experiencing a simular but more severe hiccup. He's using a 7xl, which would draw even more current than my 8xl, perhaps the controller is suddenyl dropping the motor power under extreme loads (like under hard accel) which may look like a brake stab under the right circumstance...

Don't have to do the "back to neutral" to go again, but maybe this is plane esc specific.

May not be the solution, but this fits the facts my particular hiccup, which is different than the rev to forward cogging some of you are encountering.

crazyjr · 08:37 PM

I'm running a 9XL on 12 cells NIMH 4400 max amps batteries and have no problems with it running, only rolling backwards and stabbing foreward causes a cog. I would've figured that a 9XL in an undervolt environment (according to others here) would cause a high current problem. I got some 2s 8000 mah lipo's coming and may can make something happen with those

Edit: Just a thought, How many of you with the Neu motors are running the 1/2 winds? I know there is a update coming to allow you to use the Novak and other 1/2 winds wothout problems. Just a thought

phildogg · 12.04.2006, 08:28 PM

I was wondering if it might be radio related also because it is only sometimes.. I'm going to charge up the 12 cells (gp3300) tomorrow and try them.. I think the batts should be fine (6k maxamps) esp. since they went up in price and claim more amps now..not sure but will try the other batts tomorrow..
phil

BrianG · 12.04.2006, 09:19 PM

Quote:

Originally Posted by phildogg

I was wondering if it might be radio related also because it is only sometimes.. I'm going to charge up the 12 cells (gp3300) tomorrow and try them.. I think the batts should be fine (6k maxamps) esp. since they went up in price and claim more amps now..not sure but will try the other batts tomorrow..
phil

Well, I'm using a Spektrum and you're right, it does only happen sometimes (the reverse to forward cogging). But I think it only happens occasionally because sometimes the rotot is in a "good" position.

**cogging sound -** 12.11.2006, 09:24 AM

It may be possible that it is not the ESC that is making the cogging sound. It may be one of your differentials, look at you manual and you will see the CV shaft and a pin that the gear leys over. That pin can slippe behind that gear if there is no steel shim between the diff cup and the pin.
To check this you may need to remove the drive shafts and check the amount of play. Grip the CV cup and pull and push tours the diff cup note the amount of play. There needs to be no play there (in and out movement) but the shaft needs two spin freely. You can see where the pin is slips (rubbing marks) on the back of the gear. When you are shimming the CV shaft end play you will want to check the planetary gears you may need to shim them closer this will not tighten the clearance it is just to get more of the gears to meshes (more tooth to tooth). Remember the nitro engine does not have the torque out put brushless has, and the diff tolerance was not engineered for BL. So we will need to tighten up the tolerances. Granger CO. has a large selection of shims. OFNA hyper 8 is my buggy and I ordered Shims 24@ 4mm x 6mm x.26mm and 12@ 6mm x12 mm x.26mm