If you turn it off generally no. There is no drain when turned off. If you leave it on then there is a small drain during receive with the audio squelch muted. If the squelch un-mutes and turns on the speaker then the drain goes up. The highest drain is during transmit. Typically when your not driving the car you want to turn the unit off. It could run your battery down over time much like leaving the reading lights on. If the mike falls in between the seats and actuates the push to talk button then you will be definitely late to work the next day.

Why did you have it uninstalled. Did you mean installed? Is it powered all the time or only with the ignition in the ON or ACC position?

what is the power consumption according to owner's manual or spec sheet?

It's only going to be using power if it's ON.  If your alternator is putting out the proper voltage ( about 14.5) while driving, it should be fine.  You can always test your alternator and make sure the power to the CB  is on its own, fuse protected circuit.

13.8 Volts