Electronic – Is an SPDT switch spark-free



Will this switch spark when it is switched?


I am currently working on a electric longboard and I came across this problem.
I have a LiPo battery providing power to the motor through the ESC (electronic speed controller). Now, when the batteries would run out of juice I'll have to charge them and in doing so I'll have to connect those leads to the charger. Most E-board builders use a loop-key to cut the circuit between the battery and the ESC. This is a good and working solution but the only problem is that if you were to forget to remove the loop-key you would potentially harm the ESC. An anti-spark on/off switch is more elegant solution, but still has the same problem.

My question: would an SPDT switch with the following specifications suffice?

Rated Voltage @ 15A 250VAC, 20A 125VAC



simulate this circuit – Schematic created using CircuitLab

Best Answer

If I read between the lines of your question correctly, you're not directly concerned about the spark (e.g. because it might ignite flammable gases), it's the voltage spike that would accompany it that might damage the speed control circuit. Have I interpreted your situation correctly?

If that's the case, you might consider adding a simple snubbing circuit, such as a capacitor across the switch terminals. Such a circuit absorbs the energy that would otherwise create the spark (and the voltage spike that gives rise to it), and dissipates it more gradually.

A capacitor across the terminals is probably the simplest type of snubber, but there are many more sophisticated ones; the next step up might be a simple RC network, perhaps including a diode. It depends on what's drawing the current, how much is being drawn, and how much inductance you've got in the circuit.

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