Custom Electric Parking Brake Switches

Very interesting project. It falls in line with stuff I am into. I think the person giving you this info is 100 percent wrong, leading to confusion. Braking in an electric motor context is done by shorting the poles. There is no way the motor is getting current 100 percent of the time. Although I must admit, it's been years since I was involved in fabrication of motor controllers. A quick Google search on the tech refreshes my memory a bit and leads to a salient question - first we need to know what sort of motors we are dealing with. I ASSUME they are brushless, as brushless are more efficient. But we need to know - so, is there a commutator present on the motor? A better question would be, how many wires are present, AT the motor? 2 wires would be a brushed motor. 3 wires would be a brushless. More than that... I'll have more questions. What did the motors come out of? What is actually controlling the motors? Ie, you need some sort of speed controller, at the very least, unless you plan on providing full battery voltage to the motor on/off (in which case, this whole thing is a exercise in futility, as the vehicle isn't going to be controllable, nor the drive train particularly long for the earth). I ask because - whatever is controlling the motors, is also going to be doing the braking. It then leads me to the very real possibility that trying to do the braking solution in hardware, when basic braking (brakes on/off) is already being done in software, is a great way to fry the output MOSFETS, IGTs, or whatever they are using. TLDR - need more info. Source of motors? Type/tech of motors? Controllers?"Always listen to experts. They'll tell you what can't be done, and why. Then do it. - Robert A. Heinlein"

Each motor has 2 terminals. Most late-model vehicles now employ electric parking brakes. On the back side of the LH & RH hub is a small box that contains a small DC motor. Assuming the brake is ON when the driver hops in the vehicle... When it's time to move, the driver presses the [factory-installed] switch...at which time the little motor whines for...say...2.17 seconds. It spins a short shaft which retracts the pad away from the rotor...and then stops. The pads are now fully retracted from the rotor, and they will stay that way forever - until or unless the driver lifts that same switch. When he gets to McDonalds and he's getting ready to hop out, he lifts the switch. The little motor whines for...say...2.17 seconds. Once again it spins a short shaft in the opposite direction because he lifted the switch which reverses the polarity. This squeezes the brake pads against the rotor to lock the wheel. The pads are now tightly pressing against the rotor, and they will stay that way forever - until or unless he presses the switch again. Under "normal" conditions, the brake is now applied...the engine (and therefore the flow of power) is turned off...and the brake remains locked until power is sent--in reversed polarity--to release it. The unknown factor is: What controls the duration of the power? When the driver lifts or presses the momentary switch, he does not do so for a measured length of time. He simply gives it a tug/jab, and the little motor runs for a brief time and stops. And - evidently - it is always exactly the right amount to fully apply (or release) the brake. So. We remove the circuit that came from the factory and run a new feed controlled by a DPDT Reversing Momentary switch, and we give the switch a brief tug. Does the little motor run for 2.17 seconds? I'm betting no. I'm betting it will run for as long as we maintain upward pressure on the switch...which will presumably burn out the motor fairly quickly. (Or--if we are hyper-aware--we maintain the upward pressure for...say...1.88 seconds...which may not fully apply the brake! Not good.