Need a power switch for a mobile Raspberry Pi application, so it will switch on/off 5V at a max amperage of 2.5A. Looking at a specific item, it is rated 50V, 0.5A and used by another project. How are these items rated really? Could it be used in a low-voltage application? Looking at the amount of Watts, 50V x 0.5A = 25W.
5V at 2.5A = 12.5W.

So, this is the question. Can a switch rated for a higher voltage be used for a lower voltage application and suffice, even though the amperage is not within spec?

 

The amperage is "usually" an indication of contact size of the actual
switch contacts. So no to using too small rated current.

In general - http://www.tpub.com/neets/book3/9f.htm

Regards, Dana.

 

Thanks. According top that document BOTH voltage and current ratings need to be met. I can only conclude that the part used in the GamePi project above is no good then.

 

I'll answer myself to conclude this thread. A better solution to control the load (the RPi) from the charger/Booster circuit is to use a MOSFET as a switch. I already have a logic level MODE signal that I use to switch off the boost circuit. That same signal can be used to control a MOSFET to disconnect the load efficiently. This way a small and simple on/off switch that need only handle logic level currents is needed.

I'm basing my project on the GamePi project mentioned in the first post, but instead of a powerbank I use a MP2636 charger/booster from DFRobot which I have reverse engineered to my needs. I.e lowered charge current to 1.5A and soldered connections to the MODE and ACOK signals. A microcontroller (Teensy) and a max17043 Lipo gauge is then used to monitor battery levels and shutdown commands to the RPi in case battery goes low.