View Full Version : new stereo

09-04-2007, 05:35 PM
I want to add an amp for a stereo upgrade but am afraid i may have to add a battery(i may be completely off base) and upgraded alternator . Have you or anyone else done this, heard of this, or have another suggestion? I have a '90 TS ford 351. I am wanting to add a tower with speakers also and am sure i will need an additional amp, but that is another winter. I do want to prepare for it though. all thoughts are appreciated.

09-04-2007, 05:50 PM
What do you have in the boat right now?
4 speakers running off head unit?
Do you want to add a sub?

You should be ok with the alternator, but i would add another battery!

09-04-2007, 06:01 PM
You don't HAVE to add another battery, but it would be a nice luxury. I ran two amps off one battery on my old boat and it was fine, but you could only listen to it for about two hours floating. A second battery is very nice to have for various reasons. As far as upgrading the alternator, that would only be necessary if you got into a high power multi-amp system.

09-04-2007, 11:11 PM
how should i properly install a second battery? I plan on having a sub, the four factory holes, and speakers on the tower. i assume that will require two amps, all thoughts still appreciated.

09-21-2007, 07:13 AM
I currently have a clarion apx480 and a alphasonic 4 channel 150 by 4 channel amp powering two 10 inch subs, two sets of stock componets and four 6x9 speakers. one battery....i have listened for approx. one hour without the motor being on and experienced no problem with starting. if ur going to listen witout running for more than two hours at a time, get another battery..if not, i would save the money. I always carry a jump pack, just in case..:cool:

09-21-2007, 07:48 AM
It also depends on how much power your running to your sub! Say you have a JL 1000/1 pushing a W7, thats will suck alot more juice. you can kill a battery in less than 5 mins if you wanted to!

I would say start with the amps and speakers you want, and if you are have problems with it dyeing all the time, than add a 2nd battery! I did what scott said (jump pack) for about 5 yrs! Just got tired of jumping my boat all the time!

There are a couple of different ways to run the set up you want!

1. one high powered 4 channel amp, 2 channels to push the 4 boat speakers and 2 channels to push the 2 or 4 tower speakers!

one sub amp to push the sub.

2. one high powered 4 channel amp, 2 channels to push the 4 boat speakers and the other 2 bridged to push the sub.

one 2 or 4 channel amp to push the tower.

you will be able to control the tower speakers much easier with option 2, but not get the full potential out of the sub you use! IMO I would do #1 and use the fader to control the tower!

09-21-2007, 08:49 AM
I would not upgrade the alternator, rather run two batteries with one being the standard house load and starting battery and one that is used as an auxiliary battery.

There has been a lot of research on this and running an isolator set up look below:


Yellow X9
09-21-2007, 09:26 AM
I use one of these, easy to install

09-21-2007, 10:03 AM
The one issue I have with isolators is that, being big diodes, a voltage drop occurs when going through them and this means that the normal maximum operating voltage won't be present. When a device needs 14.4Vdc to develop power, like an amplifier, the output won't be what it should. It makes a difference but an isolator is a lot cheaper than a high output alternator.

One other thing to remember- if using only one battery in a boat like this, it should be a cranking battery, not a deep cycle. Starting the boat should always be the priority and a 5.7L motor's starter doesn't want to see a deep cycle battery. Cranking batteries are also not made for discharging much more than a long cranking cycle. They lose capacity when they're discharged deeply and deep means down to about 10 volts, not dead.

09-21-2007, 10:08 AM
I run the setup Diesel recommends in his thread. Very cheap, and has not let me down yet. I have the second battery hooked up only to the amplifier and head unit.

09-21-2007, 11:01 AM
The main issue I have with running two batteries on a isolator is that there is extra draw on the alternator all the time. I have run a BlueSea systems switch and never had any problems. The battery has been drained, but I switch it to both and it starts every time. I then switch it back to #1.