Cell phones don't track people, cops do. Before cell phones, they were tapping land line phones, opening mail, and then they set up UKUSA then Echelon. They skirted US law, in monitoring the citizens in the US, by having their partner countries spy on us and then the partner countries, like the UK, would relay that data to the NSA. Technically, it wasn't "illegal" for another country to spy on us and then exchange that "spy" data with other countries. But it sure convinced some people, in the US, when our politicians said: "The US does not spy on it's own citizens..it's illegal...we have laws that prevent that".
Since 911, nearly any means of spying on US citizens is fair game. The people who wanted to spy on us, manipulated assets, destroyed evidence of decades of illegal financial activity, and now control us in every way, what we think, what we do, how we act, and what we believe has been given a relatively free reign since 911. Why do you think 911 happened? Follow the money and the results of 911...Qui Bene? Who benefits? Who benefited the most from 911...certainly not the people. The few who now have a stranglehold on America benefited greatly.
Sure, you can take your battery(ies) out of your cell phone but that will be, for most people, a very bothersome endeavor and would often forget about doing it. But you just can't trust the on-off switch to really totally turn off your phone. It could look totally dead but be rigged in such a manner as to really be broadcasting your location to the satellites or land based towers. I guess one indication would be less than expected battery drain. Of course, if one had a multimeter and a few jumper wires...they could monitor the battery current (not voltage or resistance) when the phone is off....they would have to put the multimeter in series with the batteries and the circuit...which is what the jumper wires are for...depending on the kind of battery terminals you have.
But, of course, they will still be able to track you and monitor what you say when your phone is on and you are talking to someone...or leaving messages on the internet.
Back in the 40s and 50s the Russians didn't even need a localized power source on the bug they put into the Pentagon and was activated remotely by a certain radio signal. Called the Great Seal Bug.
For many years now, spies can use a laser beam directed at a window and the conversation inside causes the window to act like a microphone and the laser beam is modulated by that window allowing the spies to hear what is said in the room..even from great distances...as long as there is a line-of-sight to the window. RFID chips, like the ones they put in debt cards and in various other products do not have an internal power source but reacts when an outside power source activates it and it has an antennae that picks up the external power which is then modulated by the RFID chip and re-radiated with the useful information. So, really you don't even need batteries in your cell phone..if your phone or even your debt cards have RFID chips then they can locate you.
I believe that the new power company digital meters that broadcasts the digital information about the amount of energy you used can also be used to broadcast anything that you do electrically, including what you do on your computer (even if you're have disconnected) from your router. If you can use your internal house wiring to act as a network then what you do electrically can be transmitted over the digital power meters.
And then there will soon be, if not already, drones flying the skies over our houses, picking up SigInt info on what we do in our houses. They have the ability to see through walls and quite probably roofs. I know this all sounds paranoid but I have read, over the years, about all of these things...and not from what some would question as unreliable sources.