Getting power form a laptop.

[dullard]

We are designing a portable device that runs entirely from a laptop. There is one part that needs to be powered though. It is a 6V DC, 10W solenoid valve. Obviously we can add batteries to the device to keep it portable, but do you think there is any way of getting this much power from the laptop battery while the laptop is running? If so, what would you use?

Size and weight is much more of a consideration than cost. Which is why we thought of using the laptop power instead of including our own batteries.

 

[zephyrprime]

USB only puts out 5V. You could use a DC-DC convertor though. Will it consume 10watts continuously? That sounds like too much power for a notebook.

 

[Jeff7]

USB only puts out 500mA, at least that's what the spec says - 5V x .5A = 2.5W.
You might need to get power directly from the AC adapter or battery pack.

You said it's a solenoid...hmm, a valve. What kind of device is this? If the valve (or solenoid) has some kind of latch, the solenoid wouldn't need to be active continuously. I would also worry about overloading the laptop's power supply, either the AC adapter, or the voltage conversion circuitry if the thing's on battery power.

 

[dullard]

Originally posted by: Jeff7
USB only puts out 500mA, at least that's what the spec says - 5V x .5A = 2.5W.
You might need to get power directly from the AC adapter or battery pack.

You said it's a solenoid...hmm, a valve. What kind of device is this? If the valve (or solenoid) has some kind of latch, the solenoid wouldn't need to be active continuously. I would also worry about overloading the laptop's power supply, either the AC adapter, or the voltage conversion circuitry if the thing's on battery power.

Yeah I know USB isn't good for me. What about ideas directly from the battery pack? No it isn't continuous use, but it will be 10W pulses (fractions of a second pulses lasting up to a minute.