Is there such thing as an iPhone data cable that JUST connects the device and does not charge it?

I have an iPhone 5 and the best way to connect it to my car stereo is USB in. The USB gives the best sound but I don't want to ruin my battery by charging and unplugging all the time. So basically IIm looking for a data cable the transfers data, but will NOT change my phone.

Bluetooth connection does that. Any cable will do the charge.

Any cable will charge your phone.

NOTE: keeping your phone charged is not bad for you phone, doing a short charge cycle will not give the phone a memory (this is left over from different nickel-cadmium batteries a long time ago). Lithium Ion batteries (the kind used in phones today) benefit from having short charge cycles as this limits the amount of the battery has been depleted.

You can read in depth articles here: http://batteryuniversity.com/learn/article/memory_myth_or_fact
and here: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Bottom line is you would only be helping your phone battery, not hurting it by keeping it charged up regularly.