Soft Latching Circuit for Anti-Spark Switch
Posted: Thu Jul 07, 2016 8:29 pm
As I am progressing forward with my longboard build, I am finding more and more areas to improve. One of these areas is the power switching system. A typical electric vehicle of any kind will have an anti spark switch. This is a solid state circuit that will slowly provide current to the motor controller to gracefully and safely charge the capacitors. After a short time, the circuit will provide full current to the controllers up to the rating of the circuit. These also come with a mechanical latching switch used to activate the circuit. They also typically have built in fuses or other safety limiter in case of an over current draw.
The anti spark switch I got was from Alien Power System and is rated for 120 Amps and up to 14s. I will be pulling up to 100 amps continuously at 10s voltage. The area I am looking to improve is the activation bit currently handled by the mechanical switch. This switch design is not ideal for the longboard application due to vibration and shock. The latching mechanism is known to break down and even unlatch while riding. While this can be replaced with a heavy duty rocker switch, it can still be knocked off while riding.
The best solution I have found is a soft latching switch circuit. This utilizes a momentary switch to latch a logic signal high or low. A slightly modified version of this circuit will yield a push on and hold off configuration. This is ideal because it is the most reliable and most robust of all the options.
I put together a quick circuit on a breadboard and interfaced it with a mosfet. I will post a full schematic once I finish it. Anyway here is a video of the working circuit.
youtu.be/UR5QIhaAFDc
It seems to work perfectly and I will next look to reduce the size of the circuit by making it on perforated board and possibly a custom pcb.
Updates to come!
The anti spark switch I got was from Alien Power System and is rated for 120 Amps and up to 14s. I will be pulling up to 100 amps continuously at 10s voltage. The area I am looking to improve is the activation bit currently handled by the mechanical switch. This switch design is not ideal for the longboard application due to vibration and shock. The latching mechanism is known to break down and even unlatch while riding. While this can be replaced with a heavy duty rocker switch, it can still be knocked off while riding.
The best solution I have found is a soft latching switch circuit. This utilizes a momentary switch to latch a logic signal high or low. A slightly modified version of this circuit will yield a push on and hold off configuration. This is ideal because it is the most reliable and most robust of all the options.
I put together a quick circuit on a breadboard and interfaced it with a mosfet. I will post a full schematic once I finish it. Anyway here is a video of the working circuit.
youtu.be/UR5QIhaAFDc
It seems to work perfectly and I will next look to reduce the size of the circuit by making it on perforated board and possibly a custom pcb.
Updates to come!