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shep70057
09-10-2007, 04:13 PM
Hey guys.... currently my boat's stereo is wired to the same battery as the amplifier. Been wondering if this would work or not so figured to ask. I would like to separate the Stereo power to my cranking battery but power my amplifier from my trolling motor battery. Can this be done??? or does the remote 12v going to the amplifier need to be referenced to the same 12v as the stereo??? Mind you, I have one cranking battery and two twolling motor batteries. The grounds are not combined.

Wile E. Coyote
09-10-2007, 06:25 PM
power is power, the amp does not know where the 12v is coming from so to the first question, yes you can separate the primary power from stereo to amp. the second part the 12v switching supply this should be powered off of the output from the radio (i.e. when the radio is keyed on, a 12v supply wire is energized, THIS connects to the amp switching wire.....)

shep70057
09-10-2007, 07:00 PM
So the 12v remote line that turns on the amplifier (from the radio) doesn't need to have the same ground reference as the amplifier????

Wile E. Coyote
09-10-2007, 07:14 PM
in car stereo and by association, boat stereos, you will get the most effective (and problem free) operation if all electronic items are grounded to the same point....im not sure (but i dont think so) if it will matter where you ground the amp or stereo, the 12v supply voltage to the amp comes from the radio, all that does is energize a relay in the amp to provide the 12v power to the amp.....so, if the radio is grounded, and the amp is grounded, they both will work, but i have always grounded to the same point, it eliminates problems (some stereos i have installed were quite complex and common ground/power points simplify matters greatly)

macutty
09-11-2007, 11:18 AM
Keeop in mind too that you'll need to leave your battery selector on dual when running your stereo wiring this way. Other wise your amps will be on or your eck but not both if only a single battery is selected.

shep70057
09-11-2007, 01:01 PM
My boat doesn't have a battery selector switch. It has two batteries directly connected via plug, to a trolling motor and one single battery directly to my motor.

Here is something that I've thought about but not sure if it can be done. Can you tie the grounds from the 24v and 12v circuits together??? If so, what are the downsides?? Now it's just the grounds.

Like the picture attached.

Ziemer
09-11-2007, 04:15 PM
I've got my amp wired completely separate from the stereo and I have a toggle switch for the remte 12V to the amp. That way if the amp gets too hot and shuts down, I can switch it off without having to turn the radio off. ;)

shep70057
09-11-2007, 04:24 PM
Zeimer, how are you able to listen to your speakers if they are wired THROUGH the amplifier when your amp cuts out???

Ziemer
09-11-2007, 04:29 PM
Currently, I've just got one amp which powers my 10" Sub, and the (4) other speakers are through the head unit only. ;)

shep70057
09-11-2007, 05:36 PM
O.K.... that makes sense now.

What I'm looking at doing is pictured below.

Wile E. Coyote
09-11-2007, 06:08 PM
there is something about that diagram that dont look right, the 24 volt batteries trouble me, and im not sure what it is....make dang sure that the power feed off the single battery is acturally 12 volts, and you should probably ground all things to the same point, insatll a bus bar if necessary....and for the record, dc voltage does indeed "flow" negative to positive....so be sure of your voltages before you hook that amp up if you ground to the 24 volt system....
Bill

shep70057
09-11-2007, 08:59 PM
Wiley... The diagram below is how it is currently wired up. And, I didn't realize that DC traveled neg to pos.

The first diagram showed how I thought about hooking things up. The second, I just added the components.

trashy
09-12-2007, 05:59 AM
First of all, I'm not so sure about connecting the negative from your cranking battery to your trolling setup. I'll have to draw myself a schematic to determine if it's possible or not.

Second, I would connect everything to the cranking battery. I'm guessing that by connecting to your trolling battery you could run into two problems. First problem, when you activate the trolling battery, there is a possibility that you will hear interference on the amp. Second problem, the trolling battery that the amp is connected to will drain at a higher rate, and lower than the other trolling battery.


So the 12v remote line that turns on the amplifier (from the radio) doesn't need to have the same ground reference as the amplifier????

Yes it does if I'm not mistaken.

trashy
09-12-2007, 06:15 AM
O.K.... that makes sense now.

What I'm looking at doing is pictured below.
I just drew a quick schematic to look at, and you DO NOT want to do that (tie grounds together), unless you want to buy a new stereo and amp, and possibly more stuff. What will effectively happen is everything will work fine until you hit that button on your trolling motor. Once you do that, you will be applying 24 volts through your amp (or whatever else is connected there).

What kind of outboard do you have? Also, what kind of cranking battery do you have? I would connect everything to your cranking battery, and make sure that your cranking battery has the capacity to run everything connected to it.

Techno
09-12-2007, 09:21 AM
If you want the radio fed from the crank battery and amp from the trolling
The radios remote on wire is fed to a relay instead of the amp. This switches the relay on. This is the 12 volt battery only.
The power side of the relay then switches positive to the amps remote on wire and walaa. This side is the 12/24 battery system.

shep70057
09-12-2007, 12:44 PM
It's a 225 Optimax Pro XS with a 1000 amp Interstate battery. Not sure of all the specifics because I'm at work right now. Reason I'm running them off the trolling motor batteries is because an amplifier will have a significant amount of power draw that I don't want on my cranking battery. I've actually run my trolling motor as it is now and there is minimal noise from it but both the radio and amplifier are hooked up to that one battery on the 24v circuit. I may have to add a 4th battery to all of this to keep things in order.....

Techno, thanks for the relay idea. Never even thought about that!!

flabum1017
09-15-2007, 09:01 AM
Ok, here it goes..... If you hook up the stereo to the engine battery and the amp to the trolling battery, you will have some issues.

First, in order for the amp to see the trigger voltage, the amp will need to be in some way grounded to the engine battery to complete the circuit for the on relay in the amp. You could overcome this by putting in a relay as said earlier, have the primary side of the relay hooked up to the ground of the stereo and to the trigger (blue wire) out of the stereo. Have the secondary (switch side) of the relay hook to the 12v pos of the amp and the trigger in to the amp. This way the trolling and engine battery can stay isolated.

If you were to hook it up without a relay, you would need to hook up the ground of the trolling battery to the ground of the engine battery,. The proble there is, when the stereo is on, and your engine battery is low, the engine battery will try to pull power thru your stereo to amp connection when you go to start the engine thereby blowing some fuses.

Here is how I would wire it:

Wile E. Coyote
09-15-2007, 09:18 AM
again, check your voltage before you hook anything up, i believe you are still pumping 24 volts to your amp and relay, with those two batteries hooked togeather, no matter where you break that circuit, your tapping 24 volts......think about it, basically, your drawing 12 volts from each battery, if you break into the circuit inbetween the two batts.....

trashy
09-15-2007, 01:55 PM
Ok, here it goes..... If you hook up the stereo to the engine battery and the amp to the trolling battery, you will have some issues.

First, in order for the amp to see the trigger voltage, the amp will need to be in some way grounded to the engine battery to complete the circuit for the on relay in the amp. You could overcome this by putting in a relay as said earlier, have the primary side of the relay hooked up to the ground of the stereo and to the trigger (blue wire) out of the stereo. Have the secondary (switch side) of the relay hook to the 12v pos of the amp and the trigger in to the amp. This way the trolling and engine battery can stay isolated.

If you were to hook it up without a relay, you would need to hook up the ground of the trolling battery to the ground of the engine battery,. The proble there is, when the stereo is on, and your engine battery is low, the engine battery will try to pull power thru your stereo to amp connection when you go to start the engine thereby blowing some fuses.

Here is how I would wire it:
It looks to me like when he activates the trolling motor that 12v becomes 24v.

shep70057
09-15-2007, 02:23 PM
Thanks guys.... that makes a lot of sense. I may even wind up buying a small motorcycle battery and use it to power my electronics.... I'll have to see about isolating it somehow to charge it on the go. That's for another day though. Thanks again!!!

sho305
09-15-2007, 03:10 PM
That last one should work, but it will unbalance the two batteries for 24v...not sure it would matter in series. I know if one of my truck batteries dies in parallel it will trash the other one. Also remember you have a ground loop in the RCAs to the amps, if it can pull a ground through those somehow it usually blows the ground in the HU and you get a pile of noise in the system. Also the trigger wire in the HU is limited in current....I would not attempt to use the trigger without relay in this way.

If you had two amps you could relay the second also and run it off the second battery to try to even them out, but a sub amp will usually take more power than high side amp...if that even matters.

It is only 24v if the circuit includes both batteries in series....I would have to look it up but you may loose some power to your trolling motor if one battery is lower than the other.

A small battery will not power an amp for long, the HU for a while but amps no unless at low volume. A good class D sub amp will take less power also.

flabum1017
09-16-2007, 08:28 AM
The positive side of the first battery in the 24V battery series will ALWAYS read 12V. It is safe to wire it the way I showed. I have done this many times. Also, a lot of the bigger boats I work on (50' and larger) have 24 volt systems and they pull off the first battery for thier 12 volt needs.



As for charging, most of those boats have a floating ground charging system that charges each battery seperately at 12 volts each. The older boats have a 24 volt charger which makes you eat batteries quickly.

shep70057
09-16-2007, 02:50 PM
Right now the way I'm charging my batteries is with the all charge unit. It cycles between the cranking and each of the two trolling motor batteries independently while running. It's proved to be a good system. For the most part my radio stays off when fishing but we use it when playing on the water.