Charger to supply power for ATmega328p

I'm building a GPS-GSM device using ATmega328P that will be installed in a car to determine its location. The power supply will come from the 12V car battery. I am thinking of using LiPo batteries to provide power to the microcontroller and the modules so that even when the car is not running, the location can still be located. Any idea on how can I create a charger for the LiPo batteries?

Also, what is the rating, rated current, input voltage, and rated power for it to work?

The charger will be connected to the car battery.

How about one of those USB chargers that plugs into the cigarette lighter socket?

Probably the easiest way to charge the battery is a 12v to 5V switching step down converter and thence a TP4056 based charger module connected to the battery.

There is however still the issue of turnming of your gadget when the Lipos get low so as to keep them safe.

Easier I would have thought to power the gadget direct from the car battery, thats going to last a lot longer than an average size Lipo.

I wanted it to be directly tapped to the car battery so the device can be hidden.

AWOL:
How about one of those USB chargers that plugs into the cigarette lighter socket?

I wanted it to be directly tapped to the car battery so the device can be hidden.

So, dismantle one of those USB chargers that plugs into the cigarette lighter socket.

srnet:
Probably the easiest way to charge the battery is a 12v to 5V switching step down converter and thence a TP4056 based charger module connected to the battery.

There is however still the issue of turnming of your gadget when the Lipos get low so as to keep them safe.

Easier I would have thought to power the gadget direct from the car battery, thats going to last a lot longer than an average size Lipo.

srnet:
Probably the easiest way to charge the battery is a 12v to 5V switching step down converter and thence a TP4056 based charger module connected to the battery.

There is however still the issue of turnming of your gadget when the Lipos get low so as to keep them safe.

Easier I would have thought to power the gadget direct from the car battery, thats going to last a lot longer than an average size Lipo.

Is it possible that the charger will provide direct power to the devices if the battery is full? And if the car is shut off, the LiPo battery will then provide power to the devices.

Also, what is the rating, rated current, input voltage, and rated power for the charger to work?

boy123456abc:
I wanted it to be directly tapped to the car battery so the device can be hidden.

So you can 'hide' a Arduino and GPS\GSM device but not a tiny 12v to 5V power supply charger.

If you have a metal bodied car, how is the GPS\GSM device going to work strapped to the car battery, under the metal bonnet ?

srnet:
So you can 'hide' a Arduino and GPS\GSM device but not a time 12v to 5V power supply charger.

If you have a metal bodied car, how is the GPS\GSM device going to work strapped to the car battery, under the metal bonnet ?

I'm sorry. What I mean by tapping directly to the car battery is to connect the wires to the cigarette lighter or the stereo, not literally the car battery.

Slightly OT: one of my neighbours had his 5 series BMW stolen a couple of months ago.
The thieves stripped a large part of the wiring out, thinking the car had a commercial tracker fitted (it didn't).
They obviously thought it worth their while to do this, replace the wiring, and still make money.

There are wires that have power even when the car is off. Think power locks and there’s one that goes to the stereo and on US cars the ciragette lighter. If you can tap a wire you can have 12v just about anywhere anytime.

The device can be pretty small even with a power supply. I would try to mount it on the rear window deck where they usually mount the subwoofer. That way you can get reception through a window. Also keep in mind that RF can get tricky. Some cars have windshields that block more than others.

If you can get the antenna in an area not covered by metal this can work.

How does your tracker communicate location? GSM?