Can't Charge/Play Music at same time in car


I purchased a Sansa Clip Zip today mainly for car use.  I installed a car stereo with a stereo input jack and a usb charge jack and I figured I could mount the mp3 player on the dash and have it plugged in for most of the time.  Well I got all the wires routed through the dash and it plays great but there’s one problem: I can’t play music when the USB cable is plugged in.  It plays fine on my AC wall adapter but for some reason when it’s in the car, all I hear is a faint “tap tap tap tap” sound.  It goes away when I disconnect the usb cable but I was hoping I could just keep both cables plugged in so it can charge while it plays.  It charges fine through the car but like I said, when it’s charging/[plugged in, the music stops

I also found out that if I just touch the outside metal of the usb connector to the metal usb jack on the radio, it stops playing and makes that “tap tap tap” noise; I don’t even have to have it plugged in.  At first I thought that having both the audio and USB cable close together might interfere with each other but I tried using a different usb cable outside the dash but the same thing happened.  

Do you have any ideas on how I could get it to charge and play at the same time when in the car?

Thanks for the help!


It sounds like it might be a ground loop interference problem. Do some Google searches about this.

I was wondering if it had something to do with the ground.  Would this work?

Just use a memory card and card reader in the car. Your stereo system is simply seeing/reading the memory space on the player; none of the player’s controls work. It’s basically seeing the player as a memory card anyway. This way you don’t have to worry about any charging, heat damage in the summertime by leaving the unit in the car, or theft.

Well the thing is, my stereo’s USB port is strictly for charging. It was one of the lower end models…

Did you try using a usb cable that is power only? That might solve the problem. These power only cables usually come with a charger or a usb battery pack, however they can be purchased separately.

Does your usb cable have a noise reducing choke?

It might be possible that noise is coming through the audio cable, and not the usb cable, however I think you should try changing the usb cable first.

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Just barely connect the USB port. It’ll work, trust me. Lol. I’ve got a Sansa Sandisk and wanted to do the same thing. Fully connected, I would get the pop-pop-pop sound, too.

But I figured out how to make it work. I have a phone charger (for the power adapter in the car) that has a USB port on it. In the USB cable (the end that connects to the power source), there’s 4 connectors. The outer two are for charging, the inner two are for data transfer. Your two options are this: Cover the inner two connectors with a tiny piece of paper to block the attempted data transfer (that’s where your popping sound is coming from), or barely plug it in so that only the outer two connectors are touching (they’re are slightly longer than the inner two).

Hope this works for you.