Series motor upgrade.

[Gonkulor]

Yes sir. I thought I would have got more from the tire size but nope. I am spinning very heavy rims though. But once up on a flat where I can GPS my speed I only get 24 tops.

[bokeasmowl]

I had stock gears, 26 inch tires , 4855 Alltrax and was doing a hair under 30mph on flat ground. DnD speed torque motor. I blew the rearend outta that big cart, put everything in my street cart and get a hair under 25 mph on 205/30-14 tires. With enough torque to leave 2 foot blackmarks on our concrete driveway. With a gear change I should get 30 mph out of that setup again.

[bokeasmowl]

I got a buddy that can get stuff made from DnD that's not even listed on their site.

[Gonkulor]

I'm interested. I don't need to leave black marks though. I have a huge 20 degree incline I need to go up to get home. Going away from home is fast. Getting home begins the crawl.

[JohnnieB]

Originally Posted by Gonkulor

..................If money is no object. What can I ask for from a series wound motor?................

Warning: The following post contains Technical Information.

When an electrical current pass through a coil of wire a magnetic field are created. When a coil of wire pass through a magnetic field, or a magnetic field passes through a coil of wire, an electric current is generated.

In a series wound motor there are stationary coils of wire (Stator windings) and moving coils or wire (Armature windings), so there are both stationary and moving magnetic fields created by the current passing through the Stator and Armature windings.

Conversely, there are also, and simultaneously, electrical currents being created (generated) by the coils of wire in the armature moving through the stationary magnetic fields of the stator windings and by the moving magnetic fields of the armature passing through the stationary coils of wire in the stator windings.

Due to the laws of physics, the current being generated by the relative movement of the magnetic field and the coils of wire is the opposite polarity as the current that is creating the magnetic fields.

The amount of current flow through an impedance is determined by the Electro-Motive Force (EMF) being applied, which is measured in Volts.

As the armature spins faster, the impedance of a motor increases because the EMF generated increases. EMF generated in this manner is known as Back-EMF.

Therefore an unloaded, friction free, series wound motor will accelerate until the Back-EMF equals the applied voltage, or centrifugal force explodes the armature.

If a motor is mechanically loaded (Drag) the RPM is limited to a point that the torque generated by the current flow (Amps) reaches an equilibrium.

This does mean that some speed increase may be obtained by getting more amps to the motor with heavier gauge wires and better electrical connections and contacts, but once the voltage losses are eliminated from the energy delivery system, the motor rpm is still limited by the applied voltage.

Increasing the number of 2V cells in the battery pack will increase the applied voltage, but the cells must have an adequate energy storage capacity or the run-time will suffer.

Bottom line is that after the energy delver system is made as efficient as possible, the only ways to make a series wound motor spin faster is to increase the applied voltage.

However a cart with a series wound motor can be made to go faster by changing the final drive ratio with different gears and/or taller tires.

Another way would be install a motor with more pairs of poles.
The stock motors I've seen have two pairs of poles. Four stator windings and four brushes on armature's split ring commutator.
I don't know if if six or eight pole series wound motors exist that will mount on a cart differential, but if they did, they would spin faster for a given applied voltage and current flow.

------------
Since, you've more or less eliminated the voltage losses in your high current system and changed the final drive ratio, more batteries are needed for more speed.

[Gonkulor]

darn you Johnnie and all you logical folks

darn you all to hell, and get your hands of me you darn dirty ape! This was an old movie quote.. I guess it was too much

I actually mean God bless you Johnnie. I know when you are right. I really need to go to 48 volts. Plus adding a beefier motor to lift the front tires off the ground.

non toilet paper using, dirty apes!

[Gonkulor]

I didn't think I said that many swear words in my last comment!. Ha. I thought I kindly blocked out one.

[fishb8]

wholly crap.
Can you make that understandable for us rednecks

[Gonkulor]

good lord, it took me many trys to see what would not filter through the forum server.

[scottyb]

For speed you might prefer a Sepex motor for a speed application... Prime example is a little PDS cart with 400 amp control and 36v reaching 24mph on stock tires.

However if you are looking for more speed from a series motor voltage is your friend. Add 33% more voltage and get just about 33% more rpms, provided your battery pack has the amperage to sustain such delivery.