Charger that doesn't kill the speaker

I have a Kensington car charge that also works through my stereo.

Problem is, when I have to drive another car for work and use that charger in a car by itself, I lose the phone speaker as soon as I plug into the dock. So my spoken GPS instructions are unheard.

Can I just get a regular cigarette usb plug and plug one of my dock cables in and regain use of my phone speaker so I can hear it again? Suggestions on brand? I'm also trying to avoid pulling mine out of my car everytime I have to drive for someone.

Verzon iPhone 4S

Thanks,
Diane

 

Thank you! Love the free shipping too

JAT - I do in my car. The ones I drive for work are either rented Sprinter vans or some fleet cars (parts deliveries) and if I could see an easy way to set it up, I would do so. But I don't.

Even in my car the hookup is through the back of the deck, which I've extended with a cable (needed an adapter anyway as it's old). I just hate pulling it apart then of course I need it in my car and realize I've left it on the counter.