Do 12V sparks damage electronics?

[lenscap]

My diy Onstep GoTo controller is basically an Arduino Mega 2560 with a RAMPS 1.5 shield, rated for 12V normal, 20V max & uses about 2A max.

It is powered from a 12V car  battery. The lead has crocodile clips at the battery & connects to 5A screw terminals on the RAMPS.

When I "power-up" by connecting the clips there is a spark at the terminal. This is expected, but does the sparking reduce the life of my electronics?

If so is there a cheap/simple way to reduce or prevent this?

I know I could put a switch in the lead but I assume the sparking would then happen inside the switch, making no difference.

 

[Alien 13]

The spark certainly can damage electronic circuitry, I would put a 100 nano farad capacitor (non electrolytic) rated at around 50 volts across the circuit to be powered and if using a switch put one across that too. You could also add a large value inductor in series with the supply as well, its worth looking at  auto accessory shops in the sound system department for an off the shelf solution too.

Alan

[symmetal]

The sparking is caused by the connection happening relatively 'slowly'. Switches like toggle or rocker design have spring mechanisms to ensure the connection or disconnection happens as quick as possible to minimise sparking. At the moment of closure the current drawn will normally be much higher than its normal operating current as capacitors in the electronics charge up. The sparking itself doesn't cause damage to the electronics but if you're tentative about attaching the clips the circuit may be made and broken several times during connection causing excessive sparking and several current surges. The repeated current surges may cause some components to fail more quickly. Putting a good toggle or rocker switch will be beneficial in the long run. The spark itself will cause erosion of the actual crocodile clips and battery connector as the spark is molten metal from the connection like a mini arc welder. Another effect is radio interference caused by the sparking which may cause momentary signal loss if picked up by cables or on your wi-fi. 

Alan

[lenscap]

Thanks for the good advice guys.

I will be fitting a rocker switch and a choke in the +12V line.

[symmetal]

If you put a choke in the 12V line you will need to connect a flyback diode across it. It's the same reason reverse biased diodes are connected across relay coils and DC motors. Without it when you turn off the switch, the choke (or inductor) will generate a high reverse voltage across itself in order to try and keep the current flowing, supplied by the magnetic energy which was stored in the inductor. This voltage can be much higher than the supply voltage and can easily damage electronic components. It would also cause a bigger spark to develop across the switch when it opened.

An RC Snubber can be connected across the switch to reduce arcing instead but these are only really needed when using highly inductive loads.

For your use just a fast acting switch on it's own will suffice. In 20 years or so when the contacts have burned away so much they are unreliable, you can replace the switch. ?

Alan