Replacing the battery.
 

This is kind of a dumb question, but I gotta ask.

I need to replace my battery. If I take the battery out, I will need the code to reset my radio(god knows where it is). To avoid this, can't I take another battery, and hook it up to the leads using jumper cables? I will then unhook the leads from the battery, change it out, and reconnect it.

This is no different from having the jumper cables hooked to the battery in another car, yes?

You can get a device that plugs into the cigarette lighter with small batteries that does the same thing but is safer and more convenient.

If you use the cigarette lighter power adapter the key will need to be on the on position to complete the circuit for radio power, I elive when the key is off the cigarette lighter circuit is also off.

I think there's an accessory that uses a 9-volt battery that plugs into the cig. lighter for just this purpose. You could even rig up a cig. lighter adapter to an external 12V battery for this purpose. Careful. With another 12V source from elsewhere, make sure the positive battery cable doesn't contact ground or you could create a direct short.

The circuit to power the radio presets is always ON (ignition ON or OFF) as is source voltage to the cigarette lighter (usually).

Sherwood