Wiper motors mandatory grounding

I ve read some threads that wiper motors should be grounded from metal body.
I ve used many DC motor with H-bridges with no problem and never done kind of grounding.
What is reason for such kind of grounding suggested by forum.

Thans a lot in advance.

As far as I see, this is valid for viper motors. For not all dc motor because there is no need to ground the body of the dc motor to drive with h-bridges.

ive read about the grounding for wiper motors and i was wondering where do i ground it to?

You actually want to disconnect the ground for use with H bridges. The whole reason to use an H bridge is to be able to reverse motor polarity so so it goes the other direction. When you reverse the polarity of the applied power, the motor frame can become “energized”. If it is mounted to a metal frame with another motor powered up the other polarity, you get a short from power to ground and can blow electronics. I used energized/power and ground to denote polarities, but it’s also +/- or however you want to think of it. In a car, the motors that use their frames as a connector all just run one way.

it's rather a de-grounding operation actually

I have added @Zed 's explanation in the FAQ

i understand what you guys are saying. i have a fully wooden 2 dof sim i have two moto monsters running off of one arduino. ive been running this for about 3 years now and though i have had issues with the wiper motor going bad over use , i have had the best time with my rig. i have never grounded the motors . not from the lack of trying but ive never understood where i was supposed to ground them to?

With low-voltage dc motors, grounding isn’t necessary for safety or otherwise. Line voltage motors probably should be grounded but I defer to manufacturer’s literature/guidance. But wiper motors are low voltage dc. With a wood frame sim, though, even if the motor frames are connected to one brush or the other, as long as there are no other continuous metal connections between the motors, you probably wouldn’t see any issues. Again, though, if your motors do have the frames connected to a brush/terminal, their frames would be electrically hot and it would be possible to spark things up if any metal was to come in contact with two or more motors.

I think I've found my grounding on my wiper motors and cut it. I have infinite ohms beween the case and all the pins. Yet when I run the motor (12 V), I'm getting about 0.05 V on the case??? It this static from the gears or what? Do I need to worry about it?

Don’t know. Even fingerprints can conduct very small currents but that’s getting to the extreme. Also, the resistance isn’t infinite. That’s an approximation. It’s just higher than your meter can measure.

Running DC motors are switching current on and off in the windings. It could just be the magnetic fields inducing a voltage somehow but that’s only a guess. Depending on your meter’s ratings, it could be the resistance between the connections and case is good enough.

i Gotcha i couldnt find the proper way of grounding so i went another method. i have seen the issue of not grounding in the specific way but as the saying goes there is more then one way to skin a cat. i was able to ground it but through isolation of other component parts that were essential to be a hard and ridged structure.
so now its fixed and being enjoyed with my favorite sim. thanks for the feed back guys. happy racing

nope. same issue but number 1 motor is fine running smc3 but running the number 2 motor it seems there is a gremlin in some where because it runs motor number 1 but bleeds into motion in motor number 2? and running the connection from motor one to motor number 2 there is the metal connection that ties to the seat? the funny thing it doesnt do this in reverse. only one way. so is it a grounding or and ? i have no idea.its on but on the track ,left cornering one way is runs smooth but the opposite on a right cornering it feels like motor 2 has a gallop. think i will put a tester on it to see if i am getting bleed over to the other motor. it doesnt make sense.

maybe its in the smc3 settings? after years of building i too will figure this out.