How to eliminate arcing in a switch?

[Topher925]

I'm working on a project where I'm connecting a big 36V battery to some electronics which contain capacitors on the power input. Of course when I connect the two I get some major arcing which likes to weld and stick connectors together. Does anyone know of a simple or easy way around this? The only thing I can think of is pre-charging by first powering up the electronics from the battery using a big resistor (~100Ohm) to prevent arcing and then connecting the battery (without resistor). Is there an easier way that doesn't involve me using two connectors?

 

[waht]

Sounds like the arcing is caused by an inrush of current. A suitable large value inductor connected in series will initially oppose the input current until steady state is reached.

 

[berkeman]

Sounds like the arcing is caused by an inrush of current. A suitable large value inductor connected in series will initially oppose the input current until steady state is reached.

So that shifts the arc to when the switch to the battery is opened...

Maybe use a SPDT (make before break) switch for the connection, and choose an appropriate resistor to give you about a 100ms time constant for the inrush charge-up of the caps. Just pause briefly in the middle switch position when turning the device on...?

 

[Dmytry]

Maybe you can simply put the switch after the capacitors?

General tip: if the current is not too big, for reliability you can also use a power MOSFET as your actual switch (make resistive voltage divider for gate voltage, use switch on that, switches are considerably more reliable at low currents).
Nowadays a power MOSFET costs under 1 euro. I got 10 of these for something around 5 euro:
http://www.irf.com/product-info/datasheets/data/irfz44n.pdf
the on resistance is 0.017 ohm, which can easily beat your switch, the off leakage is under 0.025 mA so that's not a concern either. You can make circuitry to ensure smooth turn on, with a capacitor that has to charge through resistor to bring gate voltage up on turn on, but is discharged immediately at turn off. That'd dissipate half the capacitor's energy at the mosfet during charging, i don't know how big your capacitors are but that may well be acceptable. I can draw you the circuit if you need.

 

[waht]

So that shifts the arc to when the switch to the battery is opened...

It sure does without adding a diode across the coil.