I'm using a 2S Li-ion battery to power three motors. The battery has about 8.4V fully charged and the motors and electronics draw about 1A of power. I already spent hours looking for a small switch that can be used as the main switch for this set-up. Space is very scares so the more compact the switch is the better (best would be 15mmx8mmx10mm or smaller). I already spent hours looking for such a switch with no success. Am I just looking in the wrong places or does it not exist? (the ones that I found are rated for much higher amperage and therefore are pretty big).
Any help is appreciated.
- 7-8.4V DC 1Amp on/off switch
- rocker, slide or similar type
- the smaller the better
You don’t need to look for a switch rated at such a low voltage, they don’t exist. That is the guaranteed cut-off voltage at the switch’s rated current, so as long as the switch is rated for at least 2 to 3x the maximum circuit voltage, you are good. It doesn’t take much distance to cut off 50V, so I think you’ll have a hard time finding a switch rated for much lower voltage than that.
And for a 1A draw, you want a switch rated at least 3x that, but - motors draw a lot more current on startup and stall, the switch should be rated for 2 to 3 times that amperage.
Thanks for the reply.
15mm x 8mm x 10mm or similar would be ideal. Most switches that I could find that where rated for 12VDC to 125VDC had very low amp ratings.
That is tiny. Perhaps a lower rated switch that starts the Arduino, then a separate MOSFET that turns on power to the motors independent of the switch?
Search for "ultra small microswitch" or "tiny microswitch" and you may be surprised by what you find.
These seem to fit your size and current specs: http://pewa.panasonic.com/components/switches/micro-switches/ah1/
If not for the space constraints, i'd use a circuit to do the power switching and let low current pass through the button.
Thanks for all your replies. The Panasonic on/off switches (rocker switches) are a little to big (25mm long), so I’m still looking for a switch.
Using a circuit to do power switching might actually work because the form factor will be very different from a traditional switch.
Are there any off the shelf circuits for power switching? What would such a circuit be called?