cellular tracking for car

hi

im thinking of getting a simple phone on pay as you go (no contract)
and putting it inside my car hidden

so if it gets stolen i can call the police and tell them there is a mobile phone in the car and you can track it

but as i though about it for longer i can up against some concerns and i need some help on how to solve them

1.
i dont want to attach the battery charger directly to the battery because it wil be charging forever and if i leave it for some time without starting the engine the car might not start

2.
is there something i can create so if the phone turns off it turns the phone on automaticly

is there anymore things that i should concider?

the reason why i want to do this is because the tracking systems on the market rely on paying yearly and i dont really want to do that because
the money you save in insurence is spent on tracking

fkuk said:

...
i dont want to attach the battery charger directly to the battery because it wil be charging forever and if i leave it for some time without starting the engine the car might not start

Click to expand...

The draw from the car battery will be the Cell Phone's standby current draw divided by the efficiency of the mobile charger. If I dont make any calls, my internal Cell phone battery last several days, so the average standby current draw can't be more than 30mA (2AH battery/72H). The efficiency of my 5V Switch-Mode mobile charger is about 85%, so this means that the draw from the car battery will be 30mA*(5/12)/0.85 = 15mA.

If you dont start your car for a week (168H), the amount of charge used would be 0.015*168 = 2.5 AH, which is less than 5% of the capacity of a 50AH battery. I wouldn't worry about it unless you leave your car parked for months at a time....