Motor direction - Electric Starter

[veggie]

Hi All,

I am fabricating an electric starter for the Listeroid and due to space and access  restrictions, the best side to locate
the starter is opposite to where most others have mounted theirs.
To get the flywheels spinning in the right direction I would have to make the starter spin in the opposite direction to which it was intended.
Does anyone see a problem with wiring a DC starter motor in reverse ?

veggie

[Henry W]

Hi Veggie,

Is that one of those rubber wheels that will lock in one direction and free-wheel in the other direction?

Your answer to wiring the starter motor in reverse is, I don't see any reason why it won't work on your application. If it was a regular starter with a bendex it will not work. But looking at your picture it looks like you can turn your rubber wheel around to work in reverse if needed.

Henry

[BruceM]

+1  While it's possible that the commutator timing could be off slightly so you don't have quite as much speed or power, running in reverse should work just fine on a brushed DC motor.

[veggie]

Hi Veggie,

Is that one of those rubber wheels that will lock in one direction and free-wheel in the other direction?

Your answer to wiring the starter motor in reverse is, I don't see any reason why it won't work on your application. If it was a regular starter with a bendex it will not work. But looking at your picture it looks like you can turn your rubber wheel around to work in reverse if needed.

Henry

Hi Henry, Nope...it's just a solid rubber wheel which is locked to the starter shaft by double set screw (against flat spots on the shaft).

BruceM, thanks for the feedback. ..... "Onward I go" !   

[LowGear]

Hmmmmm,

How come when I used to put my battery in backwards on my mini 12 Volt positive ground system the engine still starts.  The radio spook Chinese but the engine starts.

Casey

Ok, Ok, OK!  None of the electronics worked.

[mike90045]

Does anyone see a problem with wiring a DC starter motor in reverse ? 

If BOTH motor wires come out from the motor, it should spin backwards.  But will the bendix clutch work right ?

If the chassis is used as (-) return, you would have to wire the battery as + ground.  A bit awkward and still has the bendix issue.

[squarebob]

I was always under the impression when you reversed the polarity of a DC motor, it would run in the opposite direction. Now I have converted a 6V positive ground tractor to 12V negative ground and the starter rotated in the same direction. I don't know why. It just seems wrong to me. Have you tried to reverse the polarity? Does it spin in the opposite direction? If so you should not have a problem other than maybe a grounding issue with some other piece of equipment tied to the system. That could be solved with rubber isolation mounts. BTW that is the same starter and drive wheel I used on my GM90.

[veggie]

Does anyone see a problem with wiring a DC starter motor in reverse ?  

If BOTH motor wires come out from the motor, it should spin backwards.  But will the bendix clutch work right ?
If the chassis is used as (-) return, you would have to wire the battery as + ground.  A bit awkward and still has the bendix issue.

There is no bendix. Just a wheel attached to the starter shaft.

veggie

[veggie]

BTW that is the same starter and drive wheel I used on my GM90.

Yes, I got it from your earlier post where you gave us the part number.  

That's a good point about the grounding.
I'm not sure I want the (+) power nunning around my system frame, engine, etc....
That may "kaibosh" my plan.
Perhaps there is a way I can get this thing oriented on the correct side of the structure the eliminate this issue.
Back to the drawing board.

veggie

[Thob]

Most starter motors that I've seen are series wound DC motors.  When you reverse the battery polarity, it reverses both the field and armature, so the motor will run in the same direction.  The motor will also run on AC, for the same reason.  In order to reverse the direction of the motor, you have to reverse the field RELATIVE to the armature.  For most motors, you have to go inside the motor and swap the leads on the field or armature to accomplish this.  A quick check with your motor and a battery will confirm this.

A permanent magnet DC motor (with permanent magnets in the stationary field) will reverse direction when you change the polarity of the battery, this is because you only reverse the armature.  The field (generated by the permanent magnets) stays the same polarity.  Permanent magnet motors are used in things like power windows, which need to reverse.  Permanent magnet DC motors typically will NOT run on AC.

There are lots of other styles of DC motors, and I won't try to cover them all here...

Yep, installing the battery backwards has been a problem on automobiles for years.  It used to be that the engine would start and everything worked except the radio.  If you do that on a modern car, it might be very expensive to fix!

[SteveU.]

Hey Thob you get the brass ring! Good explanation.
Vegi the visible four POLE SHOE retaining screws in the center of the round housing are your visual indidcation this has actual copper (hopefully) series to the armature wound field coils. PM field magnets are glued in place or internally retainer separeated. To reverse this you would have to go underneath the sheet metal cover band and split out the field coil connection from the armature (through the insulated brushes) and reverse the current flow through the field coils. Could be done internally with thick heavy jumpers. Or as seen on many winch motors extended though the field case housing and then externally jumpered as a now reversible moter. Any Good local alternator/starter shop could do this for you.
DYI? Sure. Use junk auto starters for parts. Stripping these out will be your learning lesson. Letting out the majic smoke would then be your responsibility.

Casey don't reverse polarty on anything with any electronics! Ever!. Look three times; think thrice and be real, real sure.
Watched my wife jacking around literally with her new little laptop mini-speaker system yesterday doing the random plug in any possible way. Lots of screeching and howling. I ran over snatched it out of her hands. "Look Dear. Microphone logo means an input on one side an ouput on the other. Headphone logo means an output on one end of the cable and an input on the other. Speaker marked receptacle means the same. Never plug your double male ended cabling into ANY combination of these at the same time. Like to like!" She lucked out this time. She did not appreciated me interfering with her trial and error. System just did not have enough energy to make majic smoke. Toss a battery in the "the mix" it will.

And of course we ALL disconnect BOTH battery cables and alternator connections when doing any electric welding on equipment now don't we?
This used to just be a put  dollars into alternator mans SteveU's pocket mistake.
Now with Electronically Erasable Programable Memories EEPROM's you could be lobotomizing your systems.
Look up the erasure voltages.
Look up welding voltages.

Regards
Steve Unruh

[BruceM]

Thanks for the correction Thob.  I didn't realize starter motors were series field.

[LowGear]

I'm still keeping the money I won doing this swap.  There are few things sweeter than proving BS is reality.

Casey

And thanks Thob for putting it in language I can kind of understand.

[squarebob]

Thanks for the clearing up the rotation issue Thob.

[mobile_bob]

i don't know about the smaller starter, but the larger delco's have a slightly longer edge on the field pole pieces, so you might want to check yours while in there making the reconnections.

if there is a longer leading edge, all you have to do after the reconnection, is to remove the pole screws and  flip them over so the leading edge faces the other way.

like i said, i am not sure they did this on smaller starters, but they did on larger delco's because of the need for right and left hand rotation starters for right and left hand rotation engine's.

this was one of the things we were told not to forget to do on the larger starters when faced with having to reverse the rotation of a stock starter when we needed one for the opposite rotation.

the starter will work with the pole pieces left as they are, but it will run cooler, make more power and last longer from what i remember if you change them around when doing the internal reconnections.

fwiw, the gm starter was also used on liftgate hydraulic pumps, winch motor applications and the like, i found that it was much cheaper to pickup a 50 dollar starter from the autoparts store and reverse its rotation than it was to order a replacement motor for a liftgate or winch. often times those motors were 4 or 5 times the price.

bob g