ESC Programing VS Link TQi Profiles

[CTYankee]

I’ll Find out for sure next week. 1080 is on the way. The lack of noise and 3A BEC is enough a selling pint for me. The other improvements are also nice. I may leave the program cable hanging out to change settings if I so desire.

Thanks all and I’ll report what I end up doing.

Jim, what are your esc settings? Particularly running mode?

[dr frankenstyle]

You'll prob'ly like the 1080, I just carry the programmer in my toolbox in case I ever want to change things. It plugs in while everything is connected. I have mine set-up like this.

1. 3 run mode = fwd/rev
2. 1
3. 3
4. 3
5. 4
6. 3
7. 9
8. 1
9. 9
10. 4
11. 4
12. 2
13. 4
14. 1
15. 1

There's a thread , I think in the electronic section, that covers all of the 1080 settings most of the guys are using. My build thread will tell you most everything else about my set-up.
I'm not saying my way is one of the best ways .... but it works for me.


jim

[CTYankee]

Originally Posted by dr frankenstyle

I have mine set-up like this.

1. 3 run mode = fwd/rev
15. 1

Setting 1: I suspect this is what lets it control drag brake using the mf knob. This and combined with other settings may trigger the ESC to get a brake signal at neutral, letting the brake function also set drag brake. Totally guess, but I'll test it out!

Setting 15: How noisy is it at 8k? Why not 16k? Any downside to that? I like how it nearly eliminates the noise.

[dr frankenstyle]

Originally Posted by CTYankee

Setting 1: I suspect this is what lets it control drag brake using the mf knob. This and combined with other settings may trigger the ESC to get a brake signal at neutral, letting the brake function also set drag brake. Totally guess, but I'll test it out!

Setting 15: How noisy is it at 8k? Why not 16k? Any downside to that? I like how it nearly eliminates the noise.

I'm not sure how it works but it seems to work.
I'm guessing you mean #13 ? I haven't tried any other settings yet, so I don't know how it would effect things. My truck is a lot quieter than either of my buddy's 2 TRXs. Gear noise is about all you here from mine .... and the servo turning.


jim

[amigaman]

Higher PWM frequency has higher losses (heat in the ESC) and higher battery current for a given motor power.
On the other hand better control and (at least for the 16kHz setting) no noise.
In a crawler the power is no problem, and so is the heat, so go for the 16kHz. People with worn ears may use the 8kHz setting, too, but most people hear that.

For the run mode: please test thoroughly. I'd really like to know how you get the centered throttle signal to influence the drag brake...

[CTYankee]

Originally Posted by amigaman

For the run mode: please test thoroughly. I'd really like to know how you get the centered throttle signal to influence the drag brake...

Will do. I've already got a few theories on what will and will not work. I'll post them here with results. I'm in IT so testing and understanding things like this are sort of fun for me.

[CTYankee]

Originally Posted by amigaman

For the run mode: please test thoroughly. I'd really like to know how you get the centered throttle signal to influence the drag brake...

I can't get it to work. I've tried a few settings but so far the drag brake remains constant at what the ESC is programmed to apply.

When I set the MF knob to brake AND set the mode to F/B/R, the knob seems to control the brake but also the reverse. It will not reverse when set to 0.

Very odd...I need to experiment more, but using the same settings as Dr F. doesn't work for me.

[dr frankenstyle]

Originally Posted by CTYankee

I can't get it to work. I've tried a few settings but so far the drag brake remains constant at what the ESC is programmed to apply.

When I set the MF knob to brake AND set the mode to F/B/R, the knob seems to control the brake but also the reverse. It will not reverse when set to 0.

Very odd...I need to experiment more, but using the same settings as Dr F. doesn't work for me.

That IS how mine controls the reverse, along with the brake. I turn my knob up and down when I want to back up. Thot I mentioned that, 'cause it does set the reverse at the same "percentage" as the brake. But it seems to control the drag-brakes too.


jim

[amigaman]

Originally Posted by CTYankee

When I set the MF knob to brake AND set the mode to F/B/R, the knob seems to control the brake but also the reverse. It will not reverse when set to 0.

As i said earlier: That's because it is just an EPA.
If you set it to 100%, pushing the trigger forward will generate 100% reverse signal on the receiver, giving the ESC the signal to either brake full force (to what is programmed with the card) or reverse full force (to whatever is set as reverse speed with the card). Which the ESC does is determined by the drive mode and what you did last: If the car was driving, it brakes, if it stood a while it backs up. In Crawler mode it immediately backs up without braking first (nice for needing new gears).
If you set the knob to 0, pushing the trigger will not generate any signal besides "center" on the Rx, so the ESC won't even notice you did it, and hence will not brake nor back up.
Any setting in between just reduces the travel you made. e.g. you set 30% and push the finger full force, ESC still thinks it's a low 30% push and either brakes soft or reverses slow. Setting to 70% will make it brake harder or reverse faster, for the same "full push" on the lever as before.

Originally Posted by dr frankenstyle

But it seems to control the drag-brakes too.

This is not possible, as explained earlier.
At least not with the 1080 and the TQi (or any after market Rx/Tx because the 1080 does not support remote control of any setting.).
Just because Drag brake is applied when the lever is at center, the signal given needs to be "0%" or "center".
Regardless of any setting (except Trim) on the Tx it'll remain on "center" because it is solely dependent on the lever position, any Knob setting will just influence Endpoints or Speed or something, but never ever can a center signal be interpreted as either "low drag" or "high drag".
Setting Trim will make you need to readjust the ESC because it'll start to creep: Trimming is like fine adjusting the lever springs, nothing on the Rx end can know if you trimmed a lot of just have bad trigger discipline.
Even the "Auto drive" (sorry, i don't know the english terms used by Traxxas) with the set button and MuFu knob is just a sticky throttle, the ESC and Rx do not know if they're manually throttled or if that's Traxxas's convenience function: this is solely a Function of the TQi Tx and works with every ESC out there.

Yes, technically it is possible for the Rx to communicate with the ESC,...
- if the ESC usually is programmed via the ESC servo wire and not via special Port like the 1080,
- if the Rx has the functions and protocols programmed into it,
- if the Tx has the knowledge and support functions programmed into it to signal the Rx what to send to the ESC and then have it return any answers
- if you have a Method or Interface that allows the User to tell the Tx what to program on the ESC.
The Rx then camouflages itself and acts like a programming card, the servo signal wire is reused as a serial communications wire. Rx and ESC can exchange data, after setting the desired function up the ESC is restarted and the Rx changes back to servo signal mode.

The Castle based TRX-ESC are an example, some of them have a very limited set of functions controllable via Tx, the XO1 high speed unlock is such a feature. But even this only works on a very small set of ESCs out there, and even then can only control a very small subset of the possible settings. For example, the Castle counterpart of the TRX XO1 ESC can not be unlocked, just because it does not have locked or controllable power limit.

Afaik Castle has (had?) a crawler ESC that allows to control the drag level (or even any other programmable function) with a second channel.
The throttle channel still works standard, and the second is to be programmed which level to set on the preprogrammed function (like drive mode, reverse strength, drag brake, brake power and a lot more options). So by setting it up with a pot on your Tx you could control drag or drive mode remotely, using an additional channel exclusively for this control.
Which is not possible with the TQi, you'll need another Tx/Rx setup with a freely controllable channel.

[CTYankee]

I can confirm what amigaman is saying. I tested it again with a ramp and different settings. At no point was I able to increase/reduce the downward rolling rate with the multifunction knob. I would increase the ramp angle until it started rolling, then turn the knob from 0 to 100 or 100 to 0. The roll speed did not change and even if I went from 0 to 100 just as the wheels started to turn (ie minimal momentum) it would not stop the truck.

Any differences in the angle that it started to roll were due to the internal mechanical components resistance. ie the ESC is applying brake, but the gears and brushed motor also apply a "brake" force which is inconsistent. The gears/motor seemed to influence the initial break away point (what angle would initiate a forward roll). I found this by testing the same ESC/Radio settings (max/min/50% drag brake and max/min/50% drag brake rate) a few times and the results were variable. Even with no drag brake the angle could get pretty steep before it started rolling, but once it started it was much faster than with drag brake on. Once it got moving the gear motor resistance was not a factor that I could tell in my crude experiment. It seemed the relative position of the motor's windings and stators was what impacted how much "mechanical brake" was applied. This is the same force you feel when turning a bare motor, the notchiness due to the increasing magnetic force in various parts of the rotation. Maybe this is what gives the perception of adjustable drag brake?

In F/R mode the MF knob would affect the reverse speed (or disable reverse entirely below about 20%).

Inf F/B/R mode the MF knob would affect active brake power and reverse speed, but not drag brake.

Thanks all for the input. I expected this but all the same was curious to test it to see if there was some odd interaction between the Rx, Tx, and ESC.

[amigaman]

The drag brake is applied by shorting the motor wires, programming the drag force changes the PWM applied.

The motor has a magnetic force that is mainly dependent on the mechanical setup of the motor, so different types of motors behave differently, have a different breakaway torque and a different force once rotating.
This is mainly from air gap, number of slots and type of magnets. The temperature may make another difference, althogh i'd say it's negligible, or measurable at best, but not feelable.

The ESC adds brake by shorting the wires, that increases the brake torque, but as this works by loading the generated current it can only brake when the motor rotates; you can't program the ESC to fully stop the motor.

With proper gearing, a specific motor and a specific setup of the drag value in the ESC you should be able to get enough brake resistance to hold the car on every slope the wheels can hold, so it won't roll but slip or rollover.
But still: if you pull the throttle in such a situation, you switch from shorting the motor to driving it, which gets the car to roll, and then going back to drag brake may be unable to stop it.
Depending on the setting it's possible the car may slow down slowly, may just roll without changing speed, or may slowly speed up.

In this case, the ESC sees the motor generated voltage and knows it's rolling, and pulling the reverse throttle will not apply rev throttle but brake. The brake setting can be higher than the drag brake setting, so you'll be able to brake stronger than the drag can, although both methods are elctrically just shorting the motor: low drag setting shorts the motor for shorter periods than the higher brake setting.
Or, you have set up for no brake mode and reverse throttling applies reverse voltage. That may generate more resistance than just shorting the motor, but that's depending on settings and motor/gears.

tl;dr: there are a lot of settings and situations that may seem to influence drag force. A scientific approach may be needed to see why: have a controlled environment and change just one setting every time. Get all data into a table and see.