Switching a High Power & Low Power Load Together??

[HacknMod]

I have a PCB which is powered by 5v @ 1A and a motor pack which is powered by 50v @ 25A. Is it a good idea to switch these both "on" at the same time using a DPST switch such as this one? Or would there be a LOT of noise? Thanks!

[ZOMGVTEK]

I don't see it being a major issue, but it would all depend on the exact devices being powered, and how they are used.

However, what you claim sounds a little unusual. You are switching on a brushed motor to a 50V battery? That would generally require a big switch if you want it to last. If you are talking about a brushless motor, switching the controllers 'turn on' wire is generally a VASTLY superior option over the physical power. The little 5V1A PCB load isn't really a big deal, and switching them both at the same time shouldn't make any difference, assuming nothing really sensitive is always going to be connected to the same power wires.

[HacknMod]

If you are talking about a brushless motor, switching the controllers 'turn on' wire is generally a VASTLY superior option over the physical power. The little 5V1A PCB load isn't really a big deal, and switching them both at the same time shouldn't make any difference, assuming nothing really sensitive is always going to be connected to the same power wires.

I had not thought of just leaving the battery always connected and just switching on/off the "turn on" wire of the controller. Why exactly is that a vastly superior option?

[ZOMGVTEK]

It's a bad idea to switch high currents when you don't need to. Switching the controllers power under load can lead to blown FET's and a melted switch. The controllers 'Turn On' wire has somewhere about 10-20mA on it, and you can switch it under WOT without worry.

[HacknMod]

It's a bad idea to switch high currents when you don't need to. Switching the controllers power under load can lead to blown FET's and a melted switch. The controllers 'Turn On' wire has somewhere about 10-20mA on it, and you can switch it under WOT without worry.

Thanks. I think you meant "Switching the motor's power under load can lead to blown FET's." Also, can you define WOT please?

[ZOMGVTEK]

WOT = Wide Open Throttle.

It sounds like you are using a controller. If that is the case, you would want to disconnect power from the controller, which in turn supplies power to the motor. You do not disconnect power from the motor, that should be essentially permanently connected to the controller. Suddenly removing the power from the controller, or removing the motor from the controller, can both lead to voltage spikes which can take out MOSFET's. In very high power bikes, it's not a bad idea to have a few methods to kill power to the motor. Killing power to the controllers turn on wire is the best method. For long term storage, simply have a connector between the controller and battery you can remove. The controller should draw very little when switched off, but there still will be drain. It's best to only remove power from the controller when there is no load on the motor.

[HacknMod]

WOT = Wide Open Throttle.

It sounds like you are using a controller. If that is the case, you would want to disconnect power from the controller, which in turn supplies power to the motor. You do not disconnect power from the motor, that should be essentially permanently connected to the controller. Suddenly removing the power from the controller, or removing the motor from the controller, can both lead to voltage spikes which can take out MOSFET's. In very high power bikes, it's not a bad idea to have a few methods to kill power to the motor. Killing power to the controllers turn on wire is the best method. For long term storage, simply have a connector between the controller and battery you can remove. The controller should draw very little when switched off, but there still will be drain. It's best to only remove power from the controller when there is no load on the motor.

Awesome, thanks.