Everywhere I look, people emphasize the need for a good ground connection on the amp. It seems poor grounding is the mother of all unwanted noise and whining from the speakers

My local audio guy is adamant that I should connect the ground directly to the minus on the battery, given the battery's proximity as it is also mounted in the trunk area. I've done that and it works of course, but subsequently I feel a little iffy, given that I recall that whenever you jumpstart a car, you should never connect the feeding car's minus cable to the receiving car's battery minus but rather to the body of the car - I'm not sure why but I've always been told that was incredibly important! SO WHICH ISSIT, as far as an AMP goes? Direct minus to battery if the cable is relatively short, or always only to the body?

 

Meh, I always connect the negative to negative when jump starting a car. People only tell you not to because of the sparks. That said, if you do need to jump start the car, make sure you unplug your amp from the negative terminal first since the surge of power can pop the fuse in your amp.

Even if your amp isn't attached to the neg. post on the battery you should always pull the fuse out because AAA for example, uses a crazy amount of power to jump start your car.

 

+1. I ran a soundshop back in the day. Your sound guy probably isn't too familiar with BMWs or just full of BS. You never run the negative to directly to the battery, especially with BMWs. BMWs are super sensative to voltage fluctuations. All the modules will go crazy if it detects unregulated power in the system. There are quite a few grounding points in the trunk area you can use. Good luck.

 

LOL. I don't think I actually even seen batteries on the 7 BMW's i've owned when jumping or feeding. I always use the + under the hood and a strut bolt or engine hookup as a ground. I'll be damned if I dig for a battery.

With that said.....get a self tapping bolt and tap into a nice grounding spot or there are plenty of places the factory has ground bolts in the trunk under the liner.

 

Do enough of them and you will eventually get burned.

We have at least one battery explode every 15-18 months at my old dealer. Each time the tech was asked, he said he put both cables on the battery post.

Whether you go battery post to battery post or not, always make the last connection at the car with the good battery.

 

Makes jump starting a car much more interesting