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Windshield Wiper Motor vs. Stepper Motor

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(@big-al)
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Joined: 2 years ago
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I am looking for guidance.  I work with 12v DC windshield wiper motors with a PWM speed controller.  I would prefer for each motor to run flawlessly for 12 hours per day for 3 years.  Sometimes they fail in 3 months, sometimes a year and sometimes they run even longer.  A friend suggested that I use a "Nema17"  with a microstepper controller for a longer-running motor.  I know nothing about stepper motors. Can you members please make suggestions for my 12v DC motor needs?  I need for the stepper motor to have roughly the same torque as a wiper motor.  And do I truly need a microstepper controller if my power source is 12v DC?  And what about running a stepper motor with just a capacitor like I have seen on YouTube?  Is that just for AC power sources? Thank you.


   
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(@davee)
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Joined: 3 years ago
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Hi big-al,

  I am pretty sure your wiper motor will not be a stepper motor ... it will be a 12 Vdc brushed motor - i.e. with brushes and commutator. Of course, it is always tricky to know if someone has followed a different path from the rest, and I am not in the motor trade.

Assuming my guess is accurate...

There are also a number of other aspects you will need to check up on, such as how it achieves self-parking, different wipe speeds, intermittent wipe, etc., to ensure your modification does not adversely affect these functions.

As a start, I suggest you view Bill's (aka @dronebot-workshop) excellent introduction to driving DC motors  .. https://dronebotworkshop.com/dc-motor-drivers/   including the embedded video.

You will not need to know how to reverse the motor, but the rest is relevant.

---------

Sorry, I have just read Ron's (@zander) reply, and realised I may have misunderstood your question.

So in addition, my immedate reaction is that maybe your motors are simply poorly made or there is some other reason that they are not giving good service. Whilst, I have had problems with a 'cheap' mechanical link system, I personally have never suffered from a failed motor. So my first thoughts in your position would be to do a failure method analysis.

Following that, the only 'fundamental' difference you are likely to make is removing the brushes. These components have an obvious wear mechanism, which can limit life, though if they, plus the armature, bearings and commutator are well designed, should give a reasonable life and generally longer than that of the rest of the car.

However, motors can now be designed without brushes ... stepper motors are one type, so called Brushless DC (BLDC) motors are another. Both require electronics to produce the required power waveforms. Stepper motors are useful when you need to move through specific angles  e.g. in a 3D printer, whilst BLDC are useful for items that require a pseudo-continuous rotary motion.

As a direct (mechnical replacement) for a brushed DC motor, the BLDC appears a more obvious match. If you wanted a direct drive to a wiper blade doing (say) 150 degree sweep, then maybe a stepper motor could be considered.

As usual, Bill (aka @dronebot-workshop) has more excellent words of advice, which will almost certainly be helpful:

https://dronebotworkshop.com/how-does-a-quadcopter-work/

https://dronebotworkshop.com/?s=stepper

As Ron says, you will need to look at the torque requirements, etc.

Good luck, Dave


   
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Ron
 Ron
(@zander)
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@big-al As far as torque, that's just research. Look up the specs for the motor you are using, then look up the specs for any motors you are considering as replacements. Search the DroneBot Workshop Youtube channel for NEMA17 and if that sounds like a way to go the units Amazon description shows the torque (see pic). I think you will need a NEMA23 and a search on amazon will show a range. Torque is proportional to current so one I see is 4.2A and produces 425 oz in of torque. If more torque is needed then move up to NEMA43 and beyond. Based on your question it sounds like you will need to spend some significant time studying basic principles so go slow and come back to ask questions. To start describe your project in enough detail that someone can make a recommendation.

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robotBuilder
(@robotbuilder)
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@big-al

I work with 12v DC windshield wiper motors with a PWM speed controller. I would prefer for each motor to run flawlessly for 12 hours per day for 3 years.

That is a big ask! As the wiper motors use brushes they will surely eventually wear out? If you need PWM speed control that may be possible with brushless motors that use hall effect devices. So I would search for information on using 12v BLDC motors (brushless direct current motors) and their requirements.

 


   
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(@big-al)
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Joined: 2 years ago
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Topic starter  

@zander Thank you.  I will keep learning every day.


   
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(@big-al)
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Topic starter  

@robotbuilder Thank you very much...I can see right now that I have alot of sleepless nights ahead.


   
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Will
 Will
(@will)
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Posted by: @big-al

 would prefer for each motor to run flawlessly for 12 hours per day for 3 years.

Wow ! Your faith in modern technology is absolute 🙂

  Sometimes they fail in 3 months, sometimes a year and sometimes they run even longer.  A friend suggested that I use a "Nema17"  with a microstepper controller for a longer-running motor.  I know nothing about stepper motors. Can you members please make suggestions for my 12v DC motor needs?  I need for the stepper motor to have roughly the same torque as a wiper motor.

I think you'll find that the NEMA17 will be inadequate and so you'll definitely need to move up to the more powerful levels as @zander has suggested.

Anything seems possible when you don't know what you're talking about.


   
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