Large Scale Central

Pros/Cons of wiring DC motors is Series

I am no expert in DC motors, just a hobbyist but I have always heard that multiple DC motors should always be wired in parallel.

Obviously, the top speed would be drastically reduced.

What about torque and ability to tackle grades/long trains?

Effect on BEMF used to trigger chuff sounds?

Won’t the motors run at slightly different speeds causing one to “drag”?

Heat and service life of the motor?

I was about to say “all of the above”, but the speed depends on the voltage. If your track is 12V and your motors are 12V, then each will be getting a piece of the 12V, so they’ll be slow. But if your track power is 24V or 36V, the they will speed up!

This is just speculation. I have never heard of our model motors being run in series.

long ago i took two 6V motors from bump-and-run locos in series for a testbuild of a loco.
the motors ran fine with a LBG trafo. everything else didn’t.

Im gonna throw my two cents in but you can throw it right out as I am far far from any sort of expert. The way I understand it in layman’s terms is that in series, the first motor get all full shot of 12v electricity. The electricity is passed through that motor to the next which receives less due to the first motor robbing some of it. and then do on for motor #3. Now I am not sure if this would be voltage or amperage or what that my ignorance.

In parallel, from my understanding they get an equal does of electricity. And whatever is lost is lost equally between all motors.

I am a water guy and the only way electricity makes any sense to me is to think of it like water. If I have five houses in my water system and I have a single pipe and I run the water “through” the first house and then “through” the second house and so on to the last house the guy at the end isn’t gonna get much. Unless regulated the first user can use all he desires and sends the left over to the next guy who does the same. The last guy gets the balance of what is left over. But if I run a single pipe and put a tap on the pipe and feed the five houses with individual lines then more or less all five will get the same amount of water. Now that has to be qualified in that the taps are not able to deplete the water main and run out of water. I am saying if I can keep the pipe filled and at a dynamic pressure of 50PSI then all five taps will get the same mount of water that they are able to draw.

As I see this in electricity the pipe is the wire and the constant PSI is voltage. In parallel you are supplying a constant and sustainable (assuming the source is big enough to do so) voltage through a uniformly full pipe. In other words a constant full voltage down a wire that is capable of delivering that full voltage. This to me means all motors connected in parallel are going to get the exact same amount of electricity and, for the lack of a better term, the same quality of electricity as the other. In series each motor robs from the next one giving it a little less than what it got. With the last one being given the least amount.

Again take this with a grain of salt. I think I am right in principle but maybe not and I am sure there are nuances I am missing.

Water is a very good way to think of electricity. You’ve got the pipe and pressure part right (pressure equates to voltage). Gallons per Minute or Volume equates to Amperage or Current in electricity.

In series, the voltage is divided equally between the loads. If available current is limited, the first load will take what it wants and pass the rest down the line. If the first load takes it all, the additional loads will either cause the voltage to drop or the breaker to open. Oversimplified, but basically correct.

Think of it this way. 24 volt @ 10 amps supply.

2 motors in parallel, each motor gets 24 volts and 5 amps.
2 motors in series, each motor gets 12 volts and the full 10 amps.
Consider voltage as speed, and amps as torque.

As Jon said, this is rudimentary, but the best for basic understanding. There are a lot of factors that will alter the actual outcome. Unless you purchase matched motors there will ALWAYS be some differences.