Power/Ground Question

I'm currently in the process of finishing off some winter projects on the boat, the biggest being the stereo upgrade. Along with the stereo upgrade, we have added a second battery using the Blue Sea Add a Battery w/ACR. I've seen many schematics and opinions on how to best wire the stereo system so that it's most efficient and also to reduce system noise. Currently, I've got my three amps power and grounded to the stereo battery via distribution blocks. My main issue is what to do with the head unit and EQ. Currently, the head unit is power and grounded through two blocks under the helm with all the other accessories, despite being on the other side of the boat. I was planning to run the EQ the same way. The accessory power and ground blocks will be run off the stereo battery as well in order to isolate the start battery.

I'm wondering if it would be better to run dedicated power and grounds right off the stereo battery to the head unit and EQ rather than going through the accessory blocks? Would this eliminate any possible noise or is it overkill being that the accessory blocks are already coming from the stereo battery?

If your source electronics are wired in a manner that they will be connected to the SAME battery supply as the amplifiers then you probably will not have noise. But protracted wire lengths in various scenarios can still hurt you.
The most important common reference is between all audio equipment in the signal path. The ideal way is to run a source unit and EQ dedicated power and ground to the distribution blocks closest to the amplifiers. This should be a sure fire way to eliminate any potential for noise. Depending on the particular boat and equipment layout, the central point of distribution for all audio equipment may or may not be close to the battery. Just make certain to have a common point for both power and ground that is accessing one battery only and that the cable length between amplifiers and source electronics is minimized.

David

Joey,

When I added my second battery and my Blue Sea switch and ACR, I kept the head unit wired the way it was, to the starting battery, with the amps all to the house battery. I can't remember what exactly the issue was, but I ended up rewiring it so that ALL the stereo related equipment was wired to the house battery. It seems like it had something to do with the amp turn on wire, maybe? Anyway, I moved it over, and haven't had any trouble since. The draw is not very high, so the wire is not so big it is difficult to fish over.

Also, David is a genius, so do whatever he says!

Thanks guys. In trying to eliminate multiple unnecessary electrical connections and shorten wire lengths, I am considering bypassing the Blue Sea switch and going directly to the positive battery post for my amps, EQ, head unit, and accessories. I remember finding a thread with a long discussion on this topic but can't seem to find it at the moment, and hope not to recreate it. Other than not being able to fully disconnect those devices from the batteries with the switch in the off position, there really isn't anything else effected if I'm right. It should still isolate the batteries to save the start battery and also charge both when running the motor right?

Joey,
First, separate the functions of the voltage sensing relay and the manual dual circuit switch. If you use the manual switch correctly you will be able to circumvent the relay in case of a failed switch or battery. The switch can also serve to isolate the two banks for independent charging while in storage. And when the switch is in the 'ON' position it allows the relay to operate in a fully automated role providing you with both convenience and safety. Eliminating a potential parasitic draw is the least of the benefits.
All the boat and audio grounds are going to be common. These need to be distributed in a manner that does not stack too many connections on one post. Sometimes additional ground distribution is recommended.
There is no valid reason to bypass the switch posts and go directly to the batteries in order to lower resistance. The additional two terminations are secondary in resistance to stacking too many lugs per post where multiple lugs see the battery terminal only by conducting through other lugs. Also, you want to practice reductions via distribution so that you are not stacking small and large gauge lugs on the same post.
I recommend crimping AND soldering each termination lug.

David