Am I Destroying my iPod Battery? Car Charger?

I plug my iPod into my Car on the way to work and the way home from work and basically any time I'm in my car. The unit I have it plugged into is an iPod charger that happens to have a line-out built in that is connected to the back of my car stereo's AUX in. By constantly charging my iPod while it's in my car, am I shortening the life of my iPod battery for when it's not being charged?

Things l like about my car charger:
1. iPod is always charged
2. iPod does not go into standby mode (display off)
3. When I turn off the car, the iPod pauses.

My other options?
1. Just use the headphone port on my iPod to the AUX port on my CD player.
- iPod will still go into standby mode so I will have to hit the button on top to see what song is playing.
- But, then the iPod doesn't pause if I stop my car and go in a store
- By using the headphone port on my iPod, I have 2 volumes to control (stereo and iPod volumes separately)
2. Buy a direct Dock Connector to RCA cable
- Then the iPod will go into standby mode so I can't see what song is playing unless I hit the button on top.
- Less cables to attach (good thing)
- Finally I could put cups in the cup holder without the iPod charger plugged into the cigarette lighter.
- Better sound quality?

Some products I found for solution #2:
http://amazon.com/Cables-Go-35507-C...1&pf_rd_t=1501&pf_rd_p=186412001&pf_rd_i=home

http://amazon.com/Nyko-Stereo-Link-...1&pf_rd_t=1501&pf_rd_p=186412001&pf_rd_i=home