Serial or Parallel for the Z motors

What are the pros and cons for have the Z motors being wired in serial or parallel when being driven from 12V with 2.8V motors.
Thanks

Parallel Pros - Simple to wire
Parallel Cons - Non-uniform distribution of current through windings, current may recirculate around drives, any short in one motor will overload the other

Serial Pros - even current distribution across motors
Serial Cons - more complicated to wire, may need more volts for higher speeds (not usually a problem on the z-axis).

Hopefully that sums it up, unless I've missed something obvious. Many people have no trouble wiring motors up in parallel. But if you have two motors which aren't well matched (can be the same model of motor, just at each end of the manufacturers tolerances), and can't get the z-axis to behave, it's worth trying them wired serial. I have mine wired serial, and have never had a problem.

Twice the torque available for a given current in series. Higher top speed in parallel.

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[www.hydraraptor.blogspot.com]

I wired mine serial on Z, but I'm a rank noob, so feel free to discount it.

I had burned up a motor on my Y axis while fiddling with setting the currents, and then thought hard about it while awaiting a spare. I couldn't find significant downsides.

Serial seems safer, less amps, cooler for the Pololus, etc..

Nophead
Does that mean the the driver will keep the current at say 1A with about .4V on the vref pot and give me more torque but at slower Z speed.
If so at what Z speed do you think I could operate at on a prusa. As I also would like to do a Z lift between moves.
Thanks for the help.

Yes with 0.4V the driver outputs 1A. If they are in series they both get 1A, if they are in parallel they get 0.5A each.

I only get 5mm/s but that is certainly fast enough for Z lift because it only needs to lift a fraction of a millimetre.

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[www.hydraraptor.blogspot.com]

I've had good luck with them wired in series.
I made a little stripboard "breakout" with headers on it that allow me to wire the motors in series by just plugging them in.
If I ever want to change over, I just have to replace it with an even simpler stripboard with both headers in parallel.

Sorry if I'm going a bit off topic here but I don't understand why these new reprap designs have two motors for the z axis. Is there some advantage to having two motors as opposed to one motor with a belt to drive the other leadscrew? To me it seems like a pointless expense.

A closed loop belt plus two bearings cost as much as a motor and is more complicated.

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[www.hydraraptor.blogspot.com]

And a closed loop belt fixes the width of the X axis to a particular size, give or take the adjustability of the belt tightness.