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Need help from stereo expert


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I'm wiring my houseboat for sound. It has a 12v head unit powered by a couple batteries in the engine compartment. The batteries also power some other lights around the boat when not using other power. 


I have an inverter that utilizes 6 deep cycle batteries. I ran 0 ga wire to a distribution block at the entertainment system to power 3 amps. I Wired the amps up and the head unit is not sending a 12v signal to kick the amps on. I used a multimeter to check a few things and I'm getting power everywhere. However, if I put the + lead tester on the head unit power terminal AND the - lead on the amp negative it won't read anything... Both are getting power though... So I put a jumper from the amp power to the remote signal on the amp and I could get the amp to power on... 

Can I not combine from 2 12v power sources for some reason??? 


I dont see why not and now I'm stumped. Do I need to pull new power from the inverter bank to power the head unit? 

So I tied a ground from the head unit circuit to the amp, hooked into the head unit remote wire and it powered up. 

Im currently plugged into shore power so all battery banks are trickle charging. I'm getting 13.59 at the amp and 13.03 at the head unit. 


Any reason I shouldn't be doing what i am doing? 

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No you should not wire it that way for reasons and one evident now. You should have a ground strap from one bank to the other for staters. All stereo should share the same battery source, + and -. 

Edited by Truekaotik
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All audio components in the signal path should get power and ground from the identical battery bank. Period. And for many reasons other than the one you encountered, or have encountered thus far. You are also inviting noise with this practice.

As a short term fix, use a relay. The HU 12V trigger will control the relay. The relay will switch across the amplifier primary + and turn-on terminal. The two circuits within the relay are totally isolated from each other.  

However, that's a short term fix, because the ground shield (even though it may be "above" ground on the amplifier side) of the RCA interconnects will serve to circumvent the isolation between the two battery banks. Any offset in DC voltage between the two banks is certain to flow down the RCA shield ground. Not a good thing.   



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Thanks guys. I will have to pull from the inverter bank for the head unit power too then. 


 I may be asking too much here but does anyone know if it's NOT recommended to pull power from the inverter battery bank for any reason?  

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It's common for an RV to share the house bank functions with the inverter....unlike the generator battery which is usually isolated from all other functions. You should be okay. I don't envision noise issues. If you ever have a future issue it will likely be about draw versus capacity, rather than isolation.   


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Thanks David, there is space for 2 more batteries to be added to the inverter bank if needed. Bumping it up to 8 total.  The plan is to see how much it drains the system then do whatever is necessary 


Thanks again!

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