Reversing DC Starter Motors

All of the starter motors that I can think of are designed with internal grounding. To reverse direction, would probably require reversing the power and ground leads. That would not be practical on an internal ground starter motor.

But I do remember that we had a winch that used a Prestolite motor that was reversible. It was constructed just like the back end of a older starter motor(copper wire stator, not magnets).The other end looked just like a 120 volt fan motor. I think it was 1/2" shaft, about 6" sticking out of the housing. Contact www.prestolite.com .

They may be able to help you. You can also contact an automotive battery and electric shop, and find a starter re-builder in the area. They should be able to help you find a reversible 12 volt motor that you can use. Manley used to manufacture a light duty tow assembly that used the reversible electric motors. Good luck.

Reverse the polarity.

GA from me, the first correct answer when reading from the top dow!

All the others were just completely wrong!!!!

Another thing to consider is...

As starter motors for an internal combustion engines are designed to run in one direction only, their brushes and brush holders are designed for optimum life, of the brushes, in the designed direction of rotation. There is fairly good chance that the permanent reversal of the rotation of a starter motor may destroy its brushes rather quickly.

Good point that I (among others) hadn't considered. Is this speculation, or based on some evidence?

This is coming from experience. Several Harley-Davidson starter motors, I have rebuilt over the years, had their brushes set at about a 30' angle to the commutator.

This was also true for high amperage DC motors I have seen in use on battery powered forklifts and manlift type vehicles.

This acute angle of contact is also found in many automotive starter motors. This allows a greater area of contact between the brush and the commutator, and diminishes any tendency to bounce. This reduces sparking at the very high currents drawn by the motor when it begins to rotate under full load.

Starter motor brushes are often made of a copper-graphite composite, which is more conductive than carbon, but is also harder and tougher. They would probably make short work of the commutator if the motor were reversed.

I used to repair many types but still I haven't seen upto date any with a 30degree angled brusholder, although I am not debating it because I did see an interestingly wound stator once. (I believe it was not an efficient design but it did reduce the number of windings to just a single one though.)

The rotation reversal is not an easy task because the sturdy coil wires and their confinement makes it very difficult to bring them even out to reverse them, as it is the only way to reverse its direction.

You have an even greater problem that the clutch is uni-directional and I don't know how you gonna overcome that?

a dc motor direction can reverse by changing the one of connection connection of armature or field winding

Brings back fond memories of University when I did this as part of a project. It was great fun. If your definition of fun involves smoking cables, melted wires and exploding batteries, go for it!!

Here are the caveats:

(a) It won't work. Pity really. As mentioned starter motors are series wound, so reversing polarity will not reverse the motor. It will however lead to the above pyrotechnics, as the body of the motor is grounded. Exploding batteries a possibility.

(b) It won't work. Oooops. Most starters have a bendix gear to engage the flywheel. These only work in one direction.

(c) It won't work - for more than a few seconds. These motors take several hundred amps. As mentioned, you need to break into the case and seperate the internal wiring. The previous links mention brazing or soldering these cables :-) This will not work - you need a compression ferule to connect the cables reliably for this size of current. You will find there just isn't the room to get this done correctly. You will create - as I did - the worst of all outcomes; something that appears to work correctly, while in reality is just a timebomb waiting to go off. In my case the motor was not in a car - I shudder to think what might have happened given a healthy dose of petrol added to the mix.

(d) It probably won't work - for other 'special purposes'. Starter motors are cheap and nasty - the design has been honed over decades to work for only a few seconds at a time. As such they do very well. Try to do other things and you will find them unreliable. For example, they have no cooling fan, the internal wiring is woeful, etc. If your special purpose can withstand unreliability, then fair enough.

Oh well, sorry to be a killjoy. Not withstanding the above, I'd still be eager to have a go. Probably be wearing safety glasses and a fluoro jacket though

If do you like to modify this motor in reverse direction only can do conected the alimentaton negative pole in the positive conection motor and vice versa; change the pole connections.

The polarity of the field in relation to the armature polarity determines the direction of rotation.Reversing either, in relation to the other will reverse rotation.An industrial grease gun I worked on was powered by a 12 volt automotive battery,and used a ford starter with a modified output shaft to pump the grease.The negative brushes were a different composition than the positive brushes,with more carbon and less copper.The reason for this I never learned, but the motors were very durable, and easily serviced.The field windings were also easily accessible and could have been reversed if required, so I guess it depends on what type of starter motor you have. What is your application, and what type starter motor do you have?

Here is a 12 volt reversible motor from an electric winch.

« Previous | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Next »

Part Number: 304921_RP_SA12015AC DA........Motor Assy

Price: $152.27 Another possibility is to use two separate 12 volt starter motors. Use the Japanese designs that have the starter drive outboard of the bearing. pt then nose to nose, and drive from pulleys replacing the starter drives. Good luck.

I have a marine engine that is "counter-rotating" (Ford 351 cu in). The engine and the starter turn in the opposite direction of a typical car starter. Internally it has extra copper ribbon bussing to reverse some connections. I can't remember, but it may be insulated with shrink tube. I haven't traced them to understand the circuit. The buss to buss connections are like spot welds. I broke a bush holder once and replaced it with a standard part (identical) and I have replaced the brushes with standard replacement brushes from the auto parts store. That was years ago. It has operated well since 1984. It may be an Autolite or a Prestolite brand. New starters are expensive , but are available from Marine supply oultlets.