Sensored vs sensorless 4 pole brush less for rock racing and crawling

[gfmucci]

I just built a Twin Hammers kit. I installed a Hobbywing EZRUN 1/10, 1/8 scale short course truck esc/motor combo, 4 pole, brushless, sensorless, 3400k. I was shopping for a sensored combo but after I installed it I realized it was sensorless despite what I thought I ordered.

So far, with limited use on the street and in a rock garden I am pleased with the control at both low and high speed.

What am I missing not having a sensored setup for this application? I suspect climbing power at a smooth consistent crawl speed may be a weakness. But I haven't noticed any dreaded cogging or jumpiness at low speed yet. Are some sensorless setups actually half way decent for crawling?

 

[SilmarilS]

In very low speed, high torque demand, the sensorless will have trouble starting smoothly.

As you have the TwinHammer, the 2 speed transmission cure most of the problem of the slow speed coging of the sensorless.

 

[Duuuuuuuude]

Sensorless used to be a nasty cogging nightmare. Now, not so much. The HW/variant stuff I've used the past couple of years were amazingly smooth. I ran a 17.5 in my Honcho for a day and was really happy with it, then realized I had forgotten to connect the sensor wire.

 

[TacoCrawler]

2200K and lower

 

[alexchen86]

I've owned 3 sensored setup rigs for crawling.

1). A loaded CF chassis, beefed up Losi MRC 1.9 comp rig running the Excelrin system. It was fun but not my cup of tea...the high end speed was pretty sick though. Low end torque, I felt my Holmes professionally hand wound motors had more torque and smoothness especially at extremely low speeds.

2). 1.9 Wraith on scx10 axles with a MMP/TekinPro4 HD. WICKED power and smooth as glass. Still not as smooth as many of my Holmes hand wounds though. But this was a basher build not really a crawler rig!

3). 2.2 scx10 based JK Brute using Holmes BLE Waterproofed Esc and a sensored 3300kv TrailMaster also waterproofed. Work in progress.

Imo both have their ups and downs but I still prefer handwound brushed for crawlers and scalers.

 

[gfmucci]

Sensorless used to be a nasty cogging nightmare. Now, not so much. The HW/variant stuff I've used the past couple of years were amazingly smooth. I ran a 17.5 in my Honcho for a day and was really happy with it, then realized I had forgotten to connect the sensor wire.

Those more experienced with crawling than I will notice needed but missing performance characteristics way before I can. After being reminded about cogging at creep speeds I now finally noticed it.

Fortunately with my Airtronics controller I am able to adjust the throttle curves so that slow speeds occupy most of the trigger range. I'm assuming that should help some.

Do most of you set your drag brake at 100% or something a little less? 80% doesn't seem to be enough. I don't have any setting between 80 and 100%

 

[FloridaCrawler]

Newb question : What's cogging? I tried a search and just found a bunch of threads stating they were having problems with it. None actually explained the symptoms. Thanks ...sorry for the hi-jack.

 

[Noll11]

Cogging is just when the motor is going so slowly that the controller doesn't know which poles to magnetize, leading to the motor vibrating back and forth instead of spinning. Only happens at super low speeds with sensorlesa brushless motors.

As said by others above, sensorless has become very good in regards to cogging, and most of the one it's a non-issue.

 

[Olle P]

I'd just like to add that the advantage of not having a sensor is the lack of a fragile sensor cable.