Hello forum members, it’s a pleasure to have somewhere to ask this question. I’m a lawncare business owner and I run Ryobi battery handheld equipment. Ryobi isn’t a professional brand but I’ve found it to be a very good value of performance to price and is semi disposable as the battery lawncare industry is constantly evolving and I don’t want to be wrapped up in $4k worth of commercial equipment that’s built physically to live past the technology.

The problem is I’m left handed and the industry is generally built around the right handed. String trimmers (weed whackers) almost always rotate counter clockwise and it causes a lot of issues not being able to trim in the walking direction that’s required of such rotation. I’ve been using a curved shaft trimmer attachment because there’s no geared head like in a straight shaft but it holds my efficiency back considerably.

I’ve looked into this and thought I could fashion a dual direction powerhead with the use of a 6 pin mpmt rocker reversing the polarity of two wires going to the motor. I spent the morning yesterday fashioning jumpers and connectors to install the switch but when I did it only worked in the stock rotation. When the switch was changed the motor just shook. Taking the time to research further I learned that sensored brushless motors are particularly involved to reverse with good performance.

So, I’m hoping some will offer their take on what I’m up against and possible methods of attack. I realize that I’m leaving out technical information about some important specifics but maybe, if I’m lucky I wrote enough clues to narrow down my particular motor and control configuration. Here’s a picture of the whole motor and wiring assembly from Ryobi and hopefully it’s standard enough to offer some input. The other picture(s) are what I tried yesterday. I’ll add that to rule out operator error with the mpmt switch I tested reversing the polarity of two wires without the switch and it still shuttered. The whole motor assembly can be easily turned both ways so there’s no mechanical things stopping the other direction. Thanks for any input that comes to this post.

 

How will you keep the string holder from unscrewing if you go in reverse? The picture looks like the motor shaft is threaded. Is the motor a BLDC type or brushed? If BLDC that may be why it won't run in reverse rotation.

I guess my big question is I never knew a string trimmer to be right or left handed. My 3 sons are all lefties and they have no problems using trimmers.

 

How will you keep the string holder from unscrewing if you go in reverse? The picture looks like the motor shaft is threaded. Is the motor a BLDC type or brushed? If BLDC that may be why it won't run in reverse rotation.

I guess my big question is I never knew a string trimmer to be right or left handed. My 3 sons are all lefties and they have no problems using trimmers.

It’s a brushless motor, I’ll just say that I’m not going through all the trouble of trying to reverse it because I have too much free time. The threading isn’t a problem.

 

It’s a brushless motor,

Brushless motors made to turn both directions will need a way to electronically signal the stator coils in both directions since how they work. no reversing wires like a regular DC motor.

 

That's a 3-Phase-Motor .......
Do You know how to reverse a 3-Phase-Motor ?
You're not showing us how the Switch is wired.
.
.
.

 

That's a 3-Phase-Motor .......
Do You know how to reverse a 3-Phase-Motor ?
You're not showing us how the Switch is wired.
.
.
.

I swapped the red and blue wires as I’ve read numerous times that on a three phase and two wires can be switched to reverse the motor. I wired the mpmt switch to send a normal polarity and a reverse. I apologize that I’m not so fluent in drawing this but as I mentioned in the op I tested reversing it without the switch and nothing.

 

the wires were from the esc to motor also, I wasn’t swapping anything silly.

 

If the wiring diagram shown in post #1 is correct, not only do the phases need to be reversedm But also the sensors will need to be reversed. But at that point it gets complex because there is also a phase angle that may need to be adjusted. So the bottom line is that reversing a brushless DC motor is not a trivial task, closer to reversing a four-stroke engine. Not quite that hard, but similar principles.

 

You never have to reverse any sensors on a BLDC motor, that will mess up the commutation,
The drive is responsible for detecting a sensor, hall or other, when sensor is detected the phase winding is turned on by the drive,
If the drive is made for uni-directional use, then it is incapable of being run as bi-directional, IOW the drive has to be capable of full wave 3 ph bridge switching..
I have used scores of BLDC motors and drives in the CNC units I have built.

 

Off topic though I'm surprised Ryobi equipment is working good for you. My bluetooth radio failed after some light damage and a 1.5A/h lithium battery failed after getting too cold, both were less than 2 years old. The drill, impact, skill and reciprocating saws each work well though. I've been thinking about opting for dewalt or milwakee in the future..

Battery charger also failed and being home depot junk, the replacement cost me almost as much as new battery / charger combo.

 

It seems that a "practical" (though not so practical) solution for you is probably to replace the ESC. However the level of effort to do that is probably not worth the benefit in the end unless you can make it a reusable solution for when the trimmer inevitably fails mechanically or otherwise and you need a new one.

 

It is not likely that the controller or the drive motor for a string trimmer are designed for universal application, because that would certainly add to the cost of the system.
So while those motors used by Max in CNC machines include the ability to be run in both directions, it is not likely that a motor designed for a very specific function will be able to run in reverse. And consider that the timing of the phases switching is a function of the position of the motor rotor, if the controller is not intended to be reversible it may not even include the logic that the motors Max describes have. The Ryobi motors are certainly designed for one specific application. So it may not even work to reverse the sensors sequence.

 

Off topic though I'm surprised Ryobi equipment is working good for you. My bluetooth radio failed after some light damage and a 1.5A/h lithium battery failed after getting too cold, both were less than 2 years old. The drill, impact, skill and reciprocating saws each work well though. I've been thinking about opting for dewalt or milwakee in the future..

Battery charger also failed and being home depot junk, the replacement cost me almost as much as new battery / charger combo.

I totally agree here, I find it surprisingly well performing dollar for dollar. I’ve been using many pieces of Ryobi 40v outdoor equipment and the only things that have gone bad were, string trimmer attachment clamp broke, handheld blowers trigger became faulty and a snap connector on a blower tube. These tools see about 30 1/4-1/2 acre residential accounts a week. For anyone who knows this stuff I string trim with a 20” swath of .095 occasionally and it does it with gusto, many gas units can’t do this well. I’m dead serious that I’ve found Ryobi to seriously surprise me.

I tried Ego but the electronics don’t allow as precise speed control on the string trimmer and the batteries have a terrible reputation of failure. Interestingly, the ego electronics allow a simple phase wire switch to reverse the rotation.

 

This video is a little lengthy with fluff but it can quickly be forwarded to around 3 minutes where the subject matter is. This guy has the opposite problem as me, let’s just say that I’m not interested in a solid straight shaft unit, I need the compactness of an attachment model. But I believe I might be able to install the 6 pin mpmt on my Ego powerhead. Do y’all foresee any reliability problems in this gentleman’s method?

 

I totally agree here, I find it surprisingly well performing dollar for dollar. I’ve been using many pieces of Ryobi 40v outdoor equipment and the only things that have gone bad were, string trimmer attachment clamp broke, handheld blowers trigger became faulty and a snap connector on a blower tube. These tools see about 30 1/4-1/2 acre residential accounts a week. For anyone who knows this stuff I string trim with a 20” swath of .095 occasionally and it does it with gusto, many gas units can’t do this well. I’m dead serious that I’ve found Ryobi to seriously surprise me.

I tried Ego but the electronics don’t allow as precise speed control on the string trimmer and the batteries have a terrible reputation of failure. Interestingly, the ego electronics allow a simple phase wire switch to reverse the rotation.

I've only used the 18V lineup and for the money most of the tools are great entry products for light to medium duty. I bought the 5 piece bundle + radio with 2 batteries for about $400 which is nearly half price for dewalt equivalents. I ended up choosing Ryobi because their cordless impact and skill saw offered as much output as the more expensive options which I researched. Home Depot has a massive brand to protect so their in house products are slowly getting better. The 4A/h battery would also power my radio all day on high volume which really impressed me and sounded good compared to those garbage AC dewalt radios.. only problem is it got dropped and now the circuit board is fried just like the dropped charger. In construction nothing lasts long anyway especially when you put it in someone else's hands and I lost over $400 in tools last year over theft so I'm inclined to buy cheap unless I can bolt it down on the job site. I'll have to look into the 40V options, I've heard good things about them. Props for running a weed whacker all day too, I can't stand that kind of vibration.

 

Here’s a more concise video

 

I can't stand that kind of vibration.

Different with battery string trimmers, it’s a thing in the landscaping world to end up with nerve damage in the arms from petrol handheld equipment. Many here switched to electric for relief or prevention.

 

Different with battery string trimmers, it’s a thing in the landscaping world to end up with nerve damage in the arms from petrol handheld equipment. Many here switched to electric for relief or prevention.

Oh wow its about time. My dad told me a story where he couldn't feel his arms after an afternoon of weed whacking haha. Every once in a while the tendons in my hand rub due to gripping nailers. Tendonitis is absolutely debilitating, it's a miracle I've only had it a few times in my life the way I work..

 

So as I suspected after the initial simple wire switch was ineffective this would be quite involved. That’s not the end of the world as I’m a bit of a hobby tinkerer, I’m just a lot handier with mechanical things. I have some rudimentary electrical skills and I’m heavily into high end diy car audio, so I feel I’m up to the task of going so far as to even get inside the motor to switch things if necessary.

If some of y’all would be interested in continuing to advise me I would buy either an electronic assembly or just a whole bare powerhead for around a hundred bucks and have that be my project unit. Of course I’d love to have a single switchable unit but I’m not against one stock and one modified specifically for string trimmer duty. It’s probably better to have a second modified one to always have the unadulterated one for a reliable tool incase Frankenstein breaks lol. Is there any information I can furnish to aid anyone willing to participate with me on this?

 

It may well be designed to run uni-directional as is done with similar ECM motors used in HVAC systems now for blower duty.
These even include much of the electronics internal to the motor.