Sensored vs Sensorless
 

Hello,

What is the main difference between sensored and sensorless motors?
Is one better than the other for either racing or bashing?
Are there tradeoffs between them, advantages and disadvantages?

Thx

Here's a good article:

Brushless Motors: Sensored vs. Sensorless - RC TRUCK STOP

any chance of a new link? i guess I should stop reading all these old posts.. lol

Simple explained.

A brushless system reads the position of the rotor so the control (ESC) can optimise itself not to outperform the reaction speed of the rotor.

With sensorless it is done by reading the generated voltage in the coils of the motor when a magnetic pole floats along a coil like any dynamo works. The amplitude of the generated voltage is determining the speed the magnetic pole floats by. At zero RPM the esc will not read a thing as also with very low rotations. At a certain RPM level the ESC can read the feedback pulses and will work optimised with the motor, below that the ESC is a bit guessing resulting in what we call cogging.

Sensored is using electronic sensors to detect the position of the rotor. These sensors work all the time over the whole rpm range giving a much smoother control, even from when the car is standing still.

A racer wants to have the perfect start and control to get the best performance. A basher does not mind using sensorless because he wants to go full throttle and does not even notice the tiny struggling to start up.

which is more reliable? I would think sensorless would be more reliable

Both are reliable but as you can read in the electronics section it happens that the sensor cable can be the cause of some issues as also water on the sensorplate and/or in the connector can disturb the signals from the sensor although that can be solved with a few resistors on the cable.

Less parts than can go wrong, so yes, in theory it's a bit more reliable. But over all it's more about what you do with your car. If you plan on bashing it on an open area, sensorless is enough, as you'll spend very little time (or attention on) going slow. If you plan on racing (or just driving on a track) sensored makes more sense, as you need a smooth running car even in the slowest corner.

bottom line, if you want more precise control and a higher speed, then a sensored motor is the best route to go. If you want a less expensive motor, then a sensorless motor is the way to go. When it comes to reliability, 99.9% of the time, a sensor cable will go bad due to not unplugging it properly. I know this because I don't know anyone who plugs and unplugs a sensor cable more than I do, and I do it dozens of times before the cable goes bad. If you are worried about a motor being over worked with a sensor cable connected, make sure you don't turn your timing up past 40* and keep your motor temps under 120*. If the temps get too high, back off on the timing until you get the right temp. I have a sensored motor that is over 3 years old. I slapped in a new $35 rotor and it's back to performing almost like new.

Trust me, even if you're just bashing around a lot, a sensorless motor can be very glitchy when you're on and off the throttle or at low speeds. When your car is not running smooth, it can kill the fun.

Sensored is better and also worse.

I'll bite since I race and we use sensored systems. Name one way a sensored system is worse. I can name several for sensorless. Cogging and the inability to shorten motor wires jump off the top of my head but heck please educate me.

A tiny flimsy connector getting thrown around in dirt and/or water is a point of failure waiting to happen. So reliability is definitely worse. If you race seriously I guess the smoothness is worth it. I do race but it's more of a backyard (abandoned quarry) SCT league where the trucks get a serious beating and an occasional puddle crossing. 🤷

Answering general questions based on quarry basher league experience might seem helpful but if someone was asking this question to go check out a local track then your advice just cost them money. Sure for submerging your stuff in a mud puddle go cheap sensorless......any real driving it's sensored or it's worthless.

The hobbywing max10 systems have a much more reliable/sturdy sensor connection. That's the system I would use if I was worried about reliability in harsh environments.

but i get it, if you're just goofing around with friends and the competition isn't overly serious, why bother as long as everyone is having fun.

Well the question was "Is one better than the other for either racing or bashing?
Are there tradeoffs between them, advantages and disadvantages?", so... Sensorless is just fine for bashing. Depends on the system, of course, some are smooth, some are crap.

I'll get back to my non real driving now. 🤪

Sensorless is also good for racing if you want to get rid of cheaters who like to cheat with sensor timings. Also the need for rotor shimming will be less. But because the cogging issue and the option for cheating no racer wants to run sensorless. And yet, there are pretty decent sensorless ESC's to find with a decent control. I also bet if sensorless can become a new stock racing ESC's will get a better development to be race worthy.