How much power does BLE shield use?

Projects General Guidance
1

Having trouble finding information online about Bluetooth Low Energy shields in terms of how much power they use. Something like this: http://redbearlab.com/bleshield/

I wanted to build a small project for my SUV. When my phone is nearby (like very close to the car), I want to be able to wave my foot underneath the back of the car (basically under the trunk), and have the lift-gate open (like if me or my wife have groceries in both hands).

So I think I know how to handle the motion sensor, and I can have my mechanic wire it into the lift-gate, but I don't know if I can simply tap into the car's battery, because the BLE shield won't take up a lot of energy, or I need a separate battery if this thing is going to run 24/7.

Grumpy Mike, before you ask, yes, I spent a solid hour searching online for the information.

Thanks everyone!

2

If you're using a shield that suggests that you're using an official Arduino too, in which case the consumption of the Arduino is likely to be more important. I don't know what that shield will use but a typical BLE transponder would use a peak of about 15mA; the Arduino itself would use 40-50 mA.

You can do the math yourself to work out how long your battery could support that much current before it was unable to start the engine. In any case I suspect that in this application you would only want the device armed when the alarm was disarmed and you would presumably not leave the alarm disarmed for extended periods, so if you only power this project up when the alarm is disarmed the power consumption can probably be ignored.