NOTE: This HowTo is more of a howNOTto. That seems to be part and parcel to a first e-bike build.
Connecting the controller to the battery is an important yet underappreciated step in building an e-bike. With today’s battery capacities and energy densities, all e-bikes should have a properly rated fuse or circuit breaker. Care should also be taken to prevent excessive sparking when connecting the battery.
The Cyclone controller and most Battery Management Systems (BMS) have some level of over current protection. They either shut off or limit current to a preset maximum amount. However, these systems are designed to prevent equipment damage in a controlled overload situations such as stalling the motor. A catastrophic overload, such as a dead short between the positive and negative wires, can cause these circuits to ‘fail closed’.
For complete protection, e-bikes should include a device such as a fuse or circuit breaker which ‘fails open.’ Either must be rated for the proper DC voltage of the system. The simplest yet reliable solution I could come up with for new builders is an ANL style fuse with an inline holder. They are simple and reliable, yet pricy at $15.00 apiece. There are several DC circuit breakers designed for use in solar power systems that look promising.
NOTE: I had used this style fuse on an electric motorcycle build with good success. However, when the holders arrived today, it turns out they are for a different size fuse then I ordered.
The Cyclone controller is current limited to 40 amps. That will take care of most controlled overloads. I selected a fuse rated for 60 amps. By selecting a fuse with a bit more capacity than the controller, the fuse will only blow if something has gone wrong with the controller.
We also want to reduce the sparking that can happen when connecting the controller with a battery. Depending on the severity of the spark, damage can occur to the connector, controller, and battery. The first sign of a problem is pitting in the connector, which can make it difficult to insert and remove the connector plug from the socket. Eventually, this pitting can increase the resistance in the connector which can result in the connector overheating under load.
The sparking happens whenever one or more capacitors in a device like an e-bike controller are connected to a high current source such as battery. When the connection is made, the capacitor draws a brief surge of power as it charges.
One solution is to pre-charge the capacitor at low current before making the final connection between the controller and the battery. XT90 anti-spark connectors work well with the Cyclone controller. They have a small resistor connected to a ring on the end of the connector socket. To use, slightly insert the plug into the socket and pause for a second to let the capacitor pre-charge before seating the plug fully in the socket.
NOTE: Ron/SpinningMagnets had already written an excellent article on this aspect of controller to battery connectors at https://www.electricbike.com/matchin...to-controller/ . My google fu was not good enough to find the article.
Some days, it seems you go one-step forward and two-steps back. In the end, I am going to consider it a win that I came to the same conclusion as Ron about the anti-spark XT90s. Time to go for a ride to clear my head and figure out what I screwed up on with the fuse + holder order.
FWB
Connecting the controller to the battery is an important yet underappreciated step in building an e-bike. With today’s battery capacities and energy densities, all e-bikes should have a properly rated fuse or circuit breaker. Care should also be taken to prevent excessive sparking when connecting the battery.
The Cyclone controller and most Battery Management Systems (BMS) have some level of over current protection. They either shut off or limit current to a preset maximum amount. However, these systems are designed to prevent equipment damage in a controlled overload situations such as stalling the motor. A catastrophic overload, such as a dead short between the positive and negative wires, can cause these circuits to ‘fail closed’.
For complete protection, e-bikes should include a device such as a fuse or circuit breaker which ‘fails open.’ Either must be rated for the proper DC voltage of the system. The simplest yet reliable solution I could come up with for new builders is an ANL style fuse with an inline holder. They are simple and reliable, yet pricy at $15.00 apiece. There are several DC circuit breakers designed for use in solar power systems that look promising.
NOTE: I had used this style fuse on an electric motorcycle build with good success. However, when the holders arrived today, it turns out they are for a different size fuse then I ordered.
The Cyclone controller is current limited to 40 amps. That will take care of most controlled overloads. I selected a fuse rated for 60 amps. By selecting a fuse with a bit more capacity than the controller, the fuse will only blow if something has gone wrong with the controller.
We also want to reduce the sparking that can happen when connecting the controller with a battery. Depending on the severity of the spark, damage can occur to the connector, controller, and battery. The first sign of a problem is pitting in the connector, which can make it difficult to insert and remove the connector plug from the socket. Eventually, this pitting can increase the resistance in the connector which can result in the connector overheating under load.
The sparking happens whenever one or more capacitors in a device like an e-bike controller are connected to a high current source such as battery. When the connection is made, the capacitor draws a brief surge of power as it charges.
One solution is to pre-charge the capacitor at low current before making the final connection between the controller and the battery. XT90 anti-spark connectors work well with the Cyclone controller. They have a small resistor connected to a ring on the end of the connector socket. To use, slightly insert the plug into the socket and pause for a second to let the capacitor pre-charge before seating the plug fully in the socket.
NOTE: Ron/SpinningMagnets had already written an excellent article on this aspect of controller to battery connectors at https://www.electricbike.com/matchin...to-controller/ . My google fu was not good enough to find the article.
Some days, it seems you go one-step forward and two-steps back. In the end, I am going to consider it a win that I came to the same conclusion as Ron about the anti-spark XT90s. Time to go for a ride to clear my head and figure out what I screwed up on with the fuse + holder order.
FWB
Comment