Hello, I'm working on a little robot, and its tiny arms needs to swing pretty fast and a lot. I used brushed motors but long story short, they didn't fulfill the needs of the job. So I moved to brushless motors (GEPRC SPEEDX2 0802 Brushless Motor). Little tiny guys rated for 4.2 (1S) volts.
Where I'm stuck is finding a driver or ESC rated for (1S) 4.2 or less volts. Being small brushless motots I've been lost looking for parts in the drone / RC world. I've been smashing my head against the wall the last 2 weeks working on just trying to drive these damn motors...
Every ESC I find is rated for 7V or higher and its heating these up in seconds, as pretty much expected. I've found a few small ESCs but so far the two Ive tried aren't working at all. I can hear them making noise, so its likely some ESC programing issue I can't figure out. So I've only been able to make a 7+ V ESC work for testing and sanity checking purposes.
I hate these ESCs and all their bells and whistles intended for drone performance. Is there any simple 3-4V brushless drivers I'm just not seeing? If there really isn't, is there any simple 1S ESCs someone could recommend? I honestly would have never guessed it would be hard to find a 4V brushless motor driver. This is so dumb I feel like I might be missing something obvious. I just want to move a small motor backwards and forwards briefly...
Some extra bits to preempt some possible ideas/suggestions.
I've tried everything. Different initializing signals for the non working 1S ESCs and different PMW ranges, still nothing. But I am getting some start up noises out of one. Still no actual movement though.
I've tried limiting the voltage that comes out of the ESC, but that stops the motor from moving at all. My assumption is that it doesn't work because they use back EMF to know what coils to power next, and resisting any voltage in-line destroys that back signal that is needed.
I have looked into making my own ESC. Its doable, but I reallllllly don't want too unless I have too.
I've found 3 different 1S ESCs. None of them have much for documentation unfortunately. 1 just flat out doesn't work, 1 works and I can hear its initializing sounds but never spins up the motors, and the last one has yet to arrive.
As far as I can tell, all ESCs are for RC planes, helicopters, drones and cars ect. So all the terminology, knowledge base, common issues and what not are all in the RC hobbyist realm and make it hard to proceed. I've been knee deep on Google, YouTube and ChatGPT the last 2 weeks trying to get anywhere with this.
I think my work around might be trying to find small 2S motors that still fit the project. Just worried about the heat that will come out of them. I was just shocked at how hard it was to find 1S ESCs and that there isn't just standard driver boards for brushless motors of any range.
But its always something when working on a project, isn't it? Usually that's half the fun, but this issue has just been on the frustrating side of things.
Are you providing 5V on the Servo connector? I suspect that the ESC electronics use 5V even if the ESC is switching 3.7V. For higher voltages (2S, 3S...) the ESC will often have a 'BEC' (Battery Eliminator Circuit) to feed 5V out through the servo wire to feed power to the RC receiver. I don't expect that on an ESC designed for tiny 1S motors.
An ESC for a drone motor, like the motors you are using, will typically need to be 'armed' by receiving minimum throttle (servo.write(0) or servo.writeMicroseconds(1000)) before it will respond to controls. That is to prevent the motors from starting at high speed.
Yeah, I have had the Arduino powered with and without the BEC when available, still keeping common grounds between the Arduino and the ESC of course. I've tried several different initializing signals - 0, 1000, 1500. Even odd other ones in case they came with some of the other less common pre programed settings, so I tried Oneshot(125us-250us), Oneshot42(42us-8us), Multishot(2us-25us) ranges as well. but still nothing.
But little to no documentation or spec for the motor indicator noises for debugging has me stuck. Also, 1S motors are so hard to hear... lol
The 2S ESC works fine. The 1S AGFRC Mini 4A ESC makes a start up sound but I cant get it to actually move (This is the one I tried all the initializing signals on).
The MX-3A Micro Brushless ESC I bought off Ebay never worked at all.
I have a new, not yet tried 1S ESC showing up today. Hoping this one will work.
I also lucked out and happened to buy some small motors that were actually 1-2S that showed up today. Haven't tested them a lot yet, but not really getting any heat off them so going 2S might just be the easiest way. (With 2S ESCs being much more common and easier to find data sheets and guidance on).
Man after all of this, I might just market a simple,, idiot proof ESC that works off a bench top PSU with LED lights too help debug lol. I assume the hard part with finding 1S ESCs might be that the little transistors maybe not having a versatile range on them though. Usually seems to be a reasonable explanation behind most situations. Thanks for your help. I'll still try to end cap this with whatever solution I go with at some point.
My limited understanding is that there aren't that many versions of ESC firmware. BLHeli and SimonK were common in my day (a few years ago) but BlueJay seems to be another choice. Perhaps there is a way to find out what firmware is in your ESC and find documentation for that firmware.