Charger not supported bad for iphone?

I got a new iphone the other day and I went to plug it in the car audio thing and it gave me this message "charger not supported". I'm not trying to charge it, I simply want to play music in my car from my phone, but I don't know if leaving it plugged in will hurt the battery or anything. I've found some stuff online about how the phone won't allow the current to charge the battery when it detects a certain form of power, but I don't want to take any chances. Will it hurt my new iphone?

No, it won't hurt it. If it changes, it charges. If it doesn't, no harm done. Apple implemented this "feature" in iOS 4 to get you to buy new chargers. But using an unsupported device won't hurt your iPhone.