First off: Welcome William
On a plane, I dunno cause I'm new.
On a car? it's ok but i still don't like to do it. I prefer to get the trickle charger that connects direct to the battery. That way the juice goes right into the bat, and doesnt put added wear and tear on the electrical system. You have to think about fuses and such wearing out faster if they always have juice on them.
Also, I'm not sure how it is in a Cessna (or any plane) but some cars the trickle charges like this wont work cause the key has to be on to allow the circuit to be active.
My suggestion: Go to walmart/autozone/bigbox whoever and buy an add on 12v accessory power socket. Just like your cigarette lighter but designed for direct wire and higher power levels.
Wire it directly to your battery, and install a 25amp inline fuse in it. This will allow you to charge your battery directly with the charger, and also give you a SAFE extra power socket for in flight. This method is acceptable for cars, tractors, homebuilt projects and what have you. I use a setup like this to help power a Ham radio station when in the field. EDIT:// per my 1964 172 owners manual:" A ground service plug receptacle may be installed to permit the use of an external power source for cold weather starting and during lengthy maintenance of the electrical system.
Before connecting a generator type external power source it is important that the battery switch be turned ON. This will allow the battery to absorb transient voltages which otherwise might damage the transistors in the audio amplifier. When using a battery type cart, the battery switch should be turned off. "
This is just my .02 street though so please wait for a more professional opinion. I can't even start my plane yet, let alone fly if I could! Im just learning how now. I do not know about the regulations on planes yet, so please understand that while this WOULD be acceptable, it may not be LEGAL in the eyes of the FAA... I dunno.
But at any rate, I hope it gives you food for thought
But I personally WOULD NOT run a charger through the factory cigarette lighter for my reason of system fatigue listed above.