ESC comparison

[austindavid]

I do believe timing makes a difference. I haven't done much experimenting though. Sounds like less timing advance is better for your setup. I expect it will differ based on gearing, voltage, etc.

 

[kkEdlund]

I do believe timing makes a difference. I haven't done much experimenting though. Sounds like less timing advance is better for your setup. I expect it will differ based on gearing, voltage, etc.

I’m my limited experience timing does make a difference, but I don't actually know why. All my boards have run with whatever timing setting I have applied, but with some experimentation there seems to be a "sweet spot" where the system will run more efficiently, and at lower temperatures. With my (now disassembled) eZrun 150/SK3 6354 board, about 11.25* (setting 4) seemed best, although many RC forums seem to think lots of timing (like 20+*) is "better" for large outrunners. I blew up a 120A Turnigy boat esc (IDK how. Hit the brakes, and smoke...) before I could find its sweet spot, and am working with a pair of HK 90A boat escs that seem much more rugged than the Turnigy one. They are the same esc Dirkdiggler reported having success with. Current timing is 10* and they seem to run fine with the SK3 5045 motors, but I will try to bump the timing up to 15* in a few days and see what happens.

I don't pretend to understand the physics, but I have an explanation I kind of made up and seems to make sense. If someone can help correct my understanding, that would be awesome. It seems intuitive that as timing is advanced then the angular distance between magnet and energized phase increases, and more current is needed to keep the rotor moving than at lower timing levels (you need a stronger magnetic field, to exert the same force over a greater distance). If timing is retarded too far, then that angular distance is potentially reduced enough that the time between energizing a phase and the magnet passing over it is small enough you start to need more current (over a shorter time) to make the same power. I pretend to be an ME, not an EE, but that is how I rationalize the idea of timing to myself. If anyone knows the real answer, or can shed any light on something I'm missing, that would be great. Maybe it has something to do with the permanent magnet and electromagnetic fields being orthogonal for an optimized amount of time?

 

[Silenthunter]

Did anybody used this ESC - TURNIGY Sentilon100A HV 5-12S BESC (Ver4)...... http://www.hobbyking.com/hobbyking/store/__4691__TURNIGY_Sentilon100A_HV_5_12S_BESC_Ver4_.html .... for mountain board applications?

Looks interesting and cheap... I would like to use 10S for my mountain board...Any recommendations?

 

[chuttney1]

From reading around the rc forums and stuff, in general, assuming rding on a flat plane, having an advance timing like 20 degrees tends to make a motor hot at the expense of being a slight power boost. A (retarded) timing of 0 degrees may have a warm motor but is cooler than timing at 20 degrees. Notice the words "advance" and "retarded". The concept here is relatable to your car since either advancing or retarding the timing gives you a slight power boost or less. Now don't be messing with the car's timing unless you know what you are doing. Prety much what kkEdlund said in the second paragraph, two comments above this one is correct. There really isn't a real answer other than understanding the concept and optimizing it for every motor given the conditions you have.

 

[austindavid]

I tested a Hobbywing Skywalker ESC from Amazon, I got it for under $20. It's an airplane / heli ESC, 6s / 60A rated. No heat sync, it's a very small unit. Do not buy this ESC.

- I had to modify the wiiceiver code to play nice; this will go in as a configurable option in 2.0
- I had to use an RC receiver to set up the ESC. Specifically, I enabled braking. Unless I get a lot more ESCs needing throttle setup I probably won't enable wiiceiver to drive a setup program like this.

The unit seems to work just "OK". It gets crazy hot, measured over 200F on the surface; the motor was about 135F. The "brake" program takes over freewheel -- it's one or the other, and there's only one level of brakes (somewhere between "medium" and "hard"). I screwed with wiiceiver enough to get around that tho, and now it's mostly usable, but definitely not great. The ESC does something weird with brakes when hot; I can't tell if it's deciding that 55% throttle is the new neutral / brakes, or whether it's overheating and refuses to use brakes. The brakes can kick in at minimal throttle while running, which would be horrible on a dual-motor setup.

I strongly prefer the Fvt and think it's worth the extra $40 if for no other reason than variable braking.