Dual Battery w/ perko to stereo: where does the ground go?

[GoldLS1]

I plan to run my stereo from the starter battery when the motor is running and from the deep cycle when parked (hence the perko).... where is the best spot to run the ground wire (for amp and deck) to without having noise interference!?!?!

I've read that your ground should go back to the battery the power is coming from. Does it really matter? If so, how would I accomplish this when switching between batteries?


ONCE AGAIN I'M LOST!! These boats are confusing!

 

[Art Bernard]

Re: Dual Battery w/ perko to stereo: where does the ground go?

Positive wire goes from batt to rotary batt switch to fuse box. Neg wire goes from battery to fuse box (or ground strip if your fuse box dosen't have an intergal ground ). Head unit is wired to boat fuse box (hot side with a 2 amp fuse). Ground the head unit to the fuse box or ground strip. Blue wire on back of head unit is on/off for the amp, this goes to the amp. I would run the power wire/w inline fuse of correct size from your accesory battery, not your engine starting batt. That amp will suck a batt dry and you don't want to be stranded. When running the wires for speakers and amps you want to keep them sepperated so as to avoid engine whine thru the speakers. I would run the speaker wires away from any power wires (main boat power wire included). You can run the amp wire along the same route as the main power wire just make sure you are using the right sized wire and fuses. When running a dual batt set up you set the rotary switch to both for starting and running the engine, the engine will charge both batts at this time and you can run your stereo while running with no prob as the engine will be charging the accesory batt. When stoped and engine is off, set the batt switch to the acc batt so you don't drain your starting batt and strand yourself. Audio amps draw allot of power so you will drain you acc batt over time and might have to start your motor to charge it. You might consider installing a cap (capasitor) for the amp (basically a specialised battery purpose built just for audio amps)This will store power and keep the amp running longer and help with peak power draws during music playback. Hope this helps.

Art

 

[GoldLS1]

Re: Dual Battery w/ perko to stereo: where does the ground go?

I know the way you stated was the "normal" way... but will my way not work? I was going to use the perko only to switch the power between the stereo/amp from the differ batteries.

I don't see the stereo running the starter battery down while the motor is running.

If the stereo kills the deep cycle I'll end up getting an on board charger...

Please chime in if I'm off course here!!

 

[Boatist]

Re: Dual Battery w/ perko to stereo: where does the ground go?

GoldLS1
You have not given enough information for anyone to answer.
First need to know how many amps your motors alternator puts out?
Second need to know the total amps your stereo and amps take.

If your alternator is 12 amps and your stereo is 150 watts or more then the stereo will run down you battery with the motor running even at high speed.

If the stereo 500 watts with no other amps then your alternator need to put out 45 Amps to maintain the battery if you also want to charge the battery it has to be bigger still. This assumes the stereo amp is 100 percent efficient. Of course they are usually only about 60 to 80 percent efferent. This also assumes the stereo is all the way up. Likely the Stereo will not be all the way up so at 80 percent efficient 45 amps may be enough.

If you want to know if your alternator will keep up with the stereo need to know the watts of the stereo, the watts of any add in amp or bass driver.
Then need to know how many amps your motor puts out.

The year brand and type of motor may allow some to give you some estimates.
Some late model I/O may have alternator of 65 amps or more.
Most late model Outboards to not put out over 30 amps and may overheat if it had that load for more than a few minutes.

 

[Silvertip]

Re: Dual Battery w/ perko to stereo: where does the ground go?

The original question is where you get the "ground" and that obviously is at the negative terminal of the battery. The ground termiinals (negative) on both batteries should be tied together so it doesn't matter which one you ground to. However, if all you are using the switch for is to switch the stereo, you are wasting it's capabilities. Dual battery switches are discussed to death in this forum. Why not install it like and use it like for it's intended purposes.