I have one (NUSTE brand on Amazon) that has a built-in rechargeable battery. It takes up much less room than some I've had. The ones that plug in to a lighter

I have one (NUSTE brand on Amazon) that has a built-in rechargeable battery. It takes up much less room than some I've had. The ones that plug in to a lighter socket (which sometimes require the car to be running or the ignition switch in ACC position), or have to be clipped to the car battery are not as convenient.