# Y Cables Effect On Voltage

So this is something my team has been wondering about/debating for a while now. Our question is, what is a y-cable’s effect on the amount of voltage a motor receives? If two motors are y-ed together, would each motor effectively have half the power, or would they both still get the same amount of power as if they were individually plugged in?

If I’m not mistaken, the voltage will be constant, but the current would increase.

EDIT: Yep, voltage is constant but current would increase. This is because a Y-cable would make them parallel on a circuit diagram. See here for more details: Physics Tutorial: Parallel Circuits

Voltage stays the same, but the current would vary based on the load or draw from each branch of the Y. Look at Ohm’s Law with parallel circuits.

Voltage does remain constant. However, each receives half the current, or current draw is doubled, depending the configuration of both the split and the power source.

Kirchoff’s rules would mean that voltage in two branches of a parallel circuit remains constant. However, the current in each branch would be halved.

Double the current is drawn from the Cortex on that specific port. Motors have about the same performance on a y-cable.

It wouldn’t be split, because of the fact it’s a Parallel circuit… The motors have the same speed on a Y-Cable as on not on a Y-Cable.
Here’s an image of two batteries powering two lights. The left one is parallel, the right one is series.
The main reason the right one isn’t as bright is because it has two resistors, and the circuit on the right resists 2x the amount as compared to the left, making the left parallel circuit be brighter.

It seems there is a lot of confusion in this thread. When using a y cable in vex, the second motor just pulls more current from the cortex. Both motors would have the same amount of power and torque as if they where in separate ports.
Ipieroni is right.

What the motors receive is the same PWM (pulse width modulation) duty cycle if you split it with a Y cable. They do receive the same source, battery, voltage, but what they do with it depends upon the motor load. How that affects each motor depends upon what speed they are running and other things.

If you tie a drive train together with a gear train and have two motors drive it, with a Y cable, then yes, you can pretty much assume they are pulling similar loads.

However, if the Y’d motors have different loads, such that their speeds are different, then they will pull different amounts of current based upon their BEMF (backEMF). A motor that spins has a voltage that rises as the speed increases and the battery’s ability to overcome this voltage dictates the current at that speed.