batteries are supposed to be charged with matched chargers, or chargers that are designed to compensate.
200mah is really wimpy. I imagine it would work, though.
That said:
buy a proper ego style charger for all of $3-$5.
You can charge a car battery with a charger meant for a tiny lawn tractor, because they have the same voltage, but you'd be a fool to spend your time watching it happen on a daily basis.
200mah is tiny. Your DC- output in a modern car lighter holster should easily push a few amps at a low strain. Hell, the computer you're running right now can probably push 1A out of the USB's mounted to the mobo, if not twice that.