Asked
— Edited

When you hook the motor controller to the ez-b, what is the max voltage that can run on those connections of the motor controller. Do I need to regulate it or can I keep 12v through the ez-b on it?
The power which drives the motors, as Doc said is usually direct from the battery or from a different battery. The signal wires to each of the enable pins and to the PWM pins are the standard 5v from the signal pins of the digital ports.
There is only one 5V connection from EZ-B to H-Bridge, this does need to be 5v if using the L298n.
The EZ-B V4 Signal pins are 5v if you measure them with a multimeter and they are set to on or PWM at 100%. A digital on or high will set the signal pin to +5V, a digital off or low will set the signal pin to ground.
Which H-Bridge do you plan on using? Most (if not all) do require a 5V supply, this can be taken from the VCC pin on any port (V3 only) or from a 5V regulated supply from the battery. If using the V4 you will need to either supply the EZ-B with 5V or you will need to regulate a battery to 5V and power it from there.
The whole "no regulator" thing only applies to the VCC of each port on the V4.
The signals from EZ-B V3 or V4 to the H-Bridge In1 to In4 need nothing extra added.
The signals from EZ-B V3 or V4 to the EnA and EnB (or PWMs) need nothing extra added.
Any VCC from the EZ-B V4 to the H-Bridge +5v will need to be regulated.
Edit, a bit more info
@rryerson you are slightly incorrect or haven't quite understood everything correctly (not a complaint at all, we all learn). The Signal does send power to the H-Bridge but it is very low current.
If digital is set to off it sets the signal to ground.
If signal is set to on it sets the signal to +5v.
If the signal is PWM to 100% it sets the signal to +5v.
If the signal is PWM to a lower percentage it simulates a lower voltage, i.e. PWM of 50% would simulate 2.5v, PWM of 80% would simulate 4v, PWM of 20% would simulate 1v.
The In1 to In4 of the H-Bridge (sometimes called Ain1, Ain2, Bin1 and Bin2) use this high/low or +5v/ground to determine what to do. The Ena and Enb (or PWMa and PWMb) sense the speed required through PWM.
Each signal is 5v tolerant. This means each signal will read +5v when set to high or on. There will be very little current for these, just like on the V3.
You are correct, the terminal labelled 5v requires 5v. Again, check my tutorial, I included clear photos of the connections and these indicate that there is a +5v from EZ-B to +5v on the L298n, you will also be required to provide the power supply to run the motors, all others (excluding ground) are from Signal pins.