I am using the Big Pushbutton Power Switch with Reverse Voltage Protection, HP (Item #2813), to control a relay switch in my car. When there is a power drop, I have monitored it at a 0.3 volt drop (it lasts about 1-2 seconds), the Pushbutton Power Switch activates as if I had pushed the button.
Has anyone else experienced this, and is there a way for me to circumvent this problem.
More detail -
The #2813 is setup to control a relay switch that disconnects a fuse. Fuse is always to be connected until #2813’s button is pushed. #2813 receives ACC power from the fuse box (car turned off, system resets, part of the fail safe I want, fuse should only disconnect when button is pushed on the #2813).
When I turn on my rear window wiper, this is when there is a power drop of around 0.3 volts that lasts for about 1-2 seconds, then #2813 activates (as if button were pushed).
Are you measuring that 0.3V change at the battery, or at the switch itself? Also, what type of meter are you using to measure the voltage change?
The #2813 switch should be in the off state when it is first powered. What state is it in before the 0.3V change you mentioned and what state is it in after the 0.3V change?
I am using a Fluke 73 Multimeter to measure the voltage at the switch itself (standard 12 VDC car system). The #2813 switch is in the off state when it is first powered. The #2813 is in the off state before the voltage drop, after the voltage drop and the voltage returns to normal is when the switch seems to activate.
I realize that the voltage drop could be due to a poor ground somewhere in my cars electrical system, tracking that down is more than I want to mess with at the moment. But, could a voltage drop cause the switch to activate?
It is possible some conditions like that could cause the switch to power on. Brushed DC motors draw more current when starting, so there might be a short voltage drop larger than 0.3V that is not registering on the multimeter. Adding a large electrolytic capacitor (several hundred uF or more) to the supply for the board (close to the board) might help.
It is possible that the multimeter isn’t registering a larger voltage drop.
Just thought of this, is it possible that a voltage increase would cause this phenomena? Because there is the occurring voltage drop (that doesn’t cause the switch to activate) followed by a voltage increase (which is when the switch activates).
If I do add a large capacitor, say 1000 uF and the switch still activates, are there any other solutions that might be worth looking into?
A sudden voltage increase causing a problem like this is also a possibility. In addition to a capacitor, adding a diode (so the capacitor only powers the switch board, not the rest of the 12V system) would also probably help. I recommend measuring the current the switch draws when it is powering the coil of your relay so you can find a diode that can handle enough current.
