Is This Home Brew Wiring Diagram Going to Fly?

[mobetta]

 

[Deleted member 4366]

The key switch has to be on for the controller to give power. About 100mA passes through it. Is that thermo switch on the motor normally on or off? What's in it's circuitry?

 

[mobetta]

The key switch has to be on for the controller to give power. About 100mA passes through it. Is that thermo switch on the motor normally on or off? What's in it's circuitry?

The key switch is integral with the battery, so I didn't show it in the diagram. Thermo switch is normally on, i.e., passes current, if the motor overheats, the switch opens and shuts down the motor.

 

[Deleted member 4366]

What does it switch, though? Do the two wires become joined when it switches on, or does it require battery power and it switches something in the motor?

 

[mobetta]

>>What does it switch, though? Do the two wires become joined when it switches on, or does it require battery power and it switches something in the motor?

The thermal switch in the motor is a bimetal switch that opens the contacts when heated. The thermal switch wires go to the controller which has a key switch function. The key switch funtion is wired in the controller with a small control voltage. If the controller senses that the control voltage is off (motor switch opens due to overheating), then it shuts off the battery voltage to the motor.

 

[Deleted member 4366]

The key switch function is wired in the controller with a small control voltage. If the controller senses that the control voltage is off (motor switch opens due to overheating), then it shuts off the battery voltage to the motor.

I've never come across a controller that works like that. Normally the battery voltage goes directly to the output mosfets, which block it. A branch from the positive is cut down to 12v to power the mosfets, then down again to 5v to power the CPU and the sensors. The key-switch is on that branch before it's cut down. It's a simple switch that breaks the connection, so the controller remains unpowered and the output mosfets shut. Maybe your controller is different. You didn't say what it is. I assumed that it's a normal ebike one.

The only important thing is what the thermal switch does, not what it's connected to. If it's a thermostat that conducts at normal temperature and opens when too hot and can handle 100mA, it'll do what you want. If it works on logic, giving a high or low signal depending on temperature, it won't.

 

[mobetta]

>>I've never come across a controller that works like that.

This is the controller:

36 Volt
500 Watt

36V 500W Speed Controller
Designed for 36 Volt motors up to 500 Watts. Maximum current 25 Amps. Under Voltage protection 31 Volts. Current limiting feature prevents controller and motor damage due to over-current conditions. Under voltage protection feature prevents over-discharge and extends battery life. Uses standard 3-wire variable speed hall-effect throttle. Fits many common electric scooter and bicycle models.
Item # SPD-36500B
Wiring Directions

This is the Key Switch connector:

Key or Power Switch ConnectorBlue & Red Disconnected = Power Off
Blue & Red Connected = Power On

Mating Connector
Item # CNX-51

I'm not sure what level of power is put through this wire, but there has to be some way for the controller to tell if it is open or closed. I assume that this is a low monitor voltage. Unless the controller monitors the resistance in the wire and can thus tell if it is open or closed.

What is your take, how does the controller know if the Key Switch is open or closed?

>>Normally the battery voltage goes directly to the output mosfets, which block it. A branch from the positive is cut down to 12v to power the mosfets, then down again to 5v to power the CPU and the sensors. The key-switch is on that branch before it's cut down.

You said the battery power is cut down to 12V and then down again to 5V. What voltage do you suppose would be going to the connector and thus to the thermo switch in the Heinzmann?

>>It's a simple switch that breaks the connection, so the controller remains unpowered and the output mosfets shut. Maybe your controller is different. You didn't say what it is. I assumed that it's a normal ebike one.

It's a pretty normal aftermarket contemporary one.

>>The only important thing is what the thermal switch does, not what it's connected to. If it's a thermostat that conducts at normal temperature and opens when too hot and can handle 100mA, it'll do what you want. If it works on logic, giving a high or low signal depending on temperature, it won't.

It opens when it's too hot, no logic involved.