connecting controller without spark

[crimsonsnake0]

hi i have a 48v controller it does not have a third wire on the power for switch just plus and minus. my question is how can i wire it to a on and off switch to stop the spark on contact? could i use another wire like the brake cut out wires ? regards and thanks .

 

[Drunkskunk]

The spark is caused by the battery charging the controller's output capacitors. What you need is called a precharge resistor. the simplist setup is to add a simple off/on switch to the controller side battery wire. Short the pins of the switch with a 100 Ohm resistor, so that when the switch is off, power can get by through the resistor.

Have the switch off when you plug the battery in, and leave it off for a few seconds, giving time for the power to flow slowly across the resistor, then turn it on as normal.

 

[crimsonsnake0]

hi thanks for that but wont that blow the switch up putting 50v plus through it ? forgive my ignorance please thanks

 

[grindz145]

hi thanks for that but wont that blow the switch up putting 50v plus through it ? forgive my ignorance please thanks

You will still need a switch rated at 50 volts. Alternatively you can use a separate connector that you connect first, before the main connector is plugged in to precharge the capacitors.

Heres a calculator to help: http://www.scriptasylum.com/rc_speed/nospark.html

 

[Ypedal]

See the start of this video, i connect a smaller + wire first that has a resistor inline with it... then i connect the main power..

http://www.youtube.com/watch?v=onAbOtP_S-s

[youtube]onAbOtP_S-s[/youtube]

 

[Drunkskunk]

hi thanks for that but wont that blow the switch up putting 50v plus through it ? forgive my ignorance please thanks

The main reason for the voltage rating on a DC switch is so it can handle the arc when connecting. Since the resistor is taking care of that arc, it only needs to be able to handle the amps. the voltage isn't a factor. I've used a Double pole 20 amp 12 volt automotive switch, with both poles tied together to handle 40 for a long time. No ill effects in 4 years

The 2 wire system works as well

 

[crimsonsnake0]

hi so if i take one 12v 20amp switch and solder a resistor across the 2 terminals and then connect my plus from controller to it then connect the battery to the other switch terminal that will work and wont blow up ? regards

 

[torker]

Only problem is it won't work as a switch anymore. The resistor needs to be before the switch .

 

[crimsonsnake0]

okay just had a look at the diagram from grindz145 will go that way but the volts only go upto 44 my system will be aroung 60v any ideas on resistor for that or will just a 100 ohm resistor be okay ? regards