peelslancer

iTrader: (2)

i want to install a second battery in my truck. im going to use a lawn mower battery to power my system.
question is...
if i was to put the battery in my trunk an run it to my cap and amps and ground it in my trunk somewhere. would that work and not just suck the life out of it even when the car is off because the cap and amps wont be able to turn on because the remote wire is plug'd up to the deck?!?!?! i know the battery will die sooner or later because nothin is there to charge it. but, if i charge it every now and then with my battery charger everything should be all good right? or im i justway off!??!?!

BillAce

iTrader: (2)

This is an extremely bad idea for so many reasons. Why are you thinking of doing this? If an audio shop recommended this don't ever go back there.

peelslancer

iTrader: (2)

no i was just thinking about. im not going to do it unless its a good idea. thanks for the info.
why is that a bad idea?do you know the correct way of doing it?

diamondstar03

The main reason for adding a second battery to your vehicle, in relation to the stereo system, is to allow more playing time of the system with the engine off. Trying to correct a problem, such as an overload of the charging system from the stereo system, will not be eliminated by adding another battery. (It may seem as though it was helping for a short time, but the ultimate solution to that problem would be upgrading the alternator.)

If you decide that you do want to upgrade your charging system to allow two or more batteries, you must decide whether you want to use a battery isolator, or to simply wire the batteries in parallel.

It is necessary to use an isolator if you are using two different (type, model, or age) batteries or if you are giving priority to the batteries - having a dedicated "vehicle battery" and a dedicated "stereo system battery".
Usually, the isolator will allow the alternator to charge each independent battery as needed, as opposed to seeing both batteries as a single load. Sometimes you can even kill two birds with one stone by purchasing a high output alternator with dual outputs (or by using two alternators), because this does not require an isolator, and upgrades your alternator output at the same time.
An alternative in adding multiple batteries is wiring the batteries in parallel. Parallel wiring does not require an isolator, but the first thing to consider in parallel addition of batteries is that it is absolutely essential that both batteries be the exact same type, model, and should be as close to the same age as possible.
(If you add a second battery, then you also must replace the present battery in the vehicle). Adding batteries in parallel will present a single load to the alternator, so both batteries charge and discharge simultaneously.
Using either an isolator, parallel wiring two or more batteries, or using a dual output/dual alternator system will give you extended playing time when the engine is off

diamondstar03

in case you do not know how to parallel two batteries here it is

BillAce

iTrader: (2)

As was well stated above, a 2nd battery needs additional hardware to operate correctly. Even then there are problems.

Battery Isolator - This will allow you to charge 2 batteries without them drawing on each other. You need to get one that has the correct amount (current) isolation. They get large and give off heat making installation more difficult. They also cause a .7 volt drop on the output (due to the diodes used to seperate the batteries) so your voltage regulator is not seeing the real output of the alternator. I have seen soooo many failures (fires) associated with these. The serious problem (also exists with dual output alternators) is that there is only 1 field circuit that triggers the voltage regulator to charge the battery(ies).

Example 1: You are driving around on a beautiful summer afternoon, windows down, system bumping and your system battery votage is dropping. The alternator will not charge the system battery until the cars electrical system sees voltage drop to around 13.2V. So your system battery drops to 10v, the isolator gets very hot and starts to bleed voltage from teh car battery. Isolator eventually goes boom like your 15" subs.

Example 2: You are driving late at night on a dark road. The headlights are on, defroster on high, rear defogger going and the voltage regulator kicks in to charge the car battery due to the heavy draw. Your system is on very low because your concentrating on the road or talking to your girl. Eventually you smell something funny from your trunk because you are seriously overcharging the system battery. The battery can explode.

I have designed electrical systems for very high power systems that were 2 independent charging systems with independent voltage thresholds. We're talking $30K and up installs. Not practical for every day vehicles. People these days tyoically buy cheap crap equipment, install it half a$$ed and then spend a bunch of $$$$ on band aids because the system doesn't perform properly.

In all the cars I have ever built I can count the number of caps I've used on one hand. Because I installed good efficient amplifiers with plenty of internal capacitance and wired the system properly. If there were current supply problems I replaced the alternator, the only thing that makes power in a cars electrical system. The battery is just a cap that stores it. Now everone shouldn"t run out and buy a big alternator. a 100a alternator is more than enough for 1000 watts or about 150 amps of draw. This is because music is dynamic, impedance is frequency dependent and the number printed on the box fir the speaker or amp mean next to nothing.

If there is a problem fix it, don't spend a bunch of money after the fact on band aids.

Bill

peelslancer

iTrader: (2)

thanks for all the info. my main reason for adding a second battery is just to get rid of the noise from the alternator. i do have a noise filter but i still get the noise. so, i thought a second battery would do the trick.
i guess i'll just get a yellow top optima for now and see if that helps before i fork over 300 bucks for a bigger alternator.

jchangsta2six

iTrader: (1)

i would just go with the yellow optima

BillAce

iTrader: (2)

No new or additional battery is a cure for noise and a noise filter is one of those band aids. They do not know the difference between noise and audio signal and just block everything in that frequency range. Something is wrong, bad audio cable, sh!tty amp, ground loop etc. Mute the input of the amp and see if the noise is still there. Get a cheap RCA cable and cut the end off. Short the 2 conductors together (sheild and center pin). Plug that into your amp instead of the RCA cable from your head unit and turn the system on. If there is noise the amp is the problem. If not check the RCA cable or the head unit for a problem. Run a new RCA from the head unit to the amp without taking the car apart, try a different pre amp output on the head unit, make sure the head unit has a good ground source, (some vehicles stereo harnesses do not have a ground wire in the harness and the antenna could be the ground connection.

peelslancer

iTrader: (2)

i actually tried all that last night. it might be a sh!tty amp because the only speakers that make the noise are my highs and mids(hook'd up to a 300watt BOSS 4champ). my subs are fine except when i turn the car on they kinda make "thump" noise. when i turn the car off my rear speakers make a noise(the kind of noise that you would get from the alternator when the car is on) and it stays like that for a good 5-10 min could it be because the amp is still drawing from the cap?

or better yet...can you just come to my house and tell me what i am doing wrong!?!?

i have installed a system before in my other cars. this is the first car that i am doing with more than 2 amps and a cap.

BillAce

iTrader: (2)

Boss audio is one of the heavily optomistic amp companies. It likely is the amp that is the source of the noise. Is the amp mounted to the car directly. I have seen cases where the chassis of the amp connected directly to the ground plane (car) will cause noise. If it is just put wood or something between the amp and car and that may help. You may also try swapping amps, the alternator whine in the subs wouldn't be noticeable.

peelslancer

iTrader: (2)

all the amps on mounted to box....i'll take some pictures tomorrow so i can show you how i have everything set up. i prolly just did a crappy job !!!

BillAce

iTrader: (2)

Are the mids and highs component speakers with a passive xover? Passive xovers can induce noise and their location could be your problem. It isn;t likely that both left and right would have the same noise problem but worth checking.

peelslancer

iTrader: (2)

yea they are on a passive crossover...my cap stays on all the time and now my battery is dead! but i dont know why it would stay on. isnt the remote sapposed to turn the cap on?!?!?!

BillAce

iTrader: (2)

A cap should be live to the battery at all times unless its a carbon alloy type. If it has a display or volt gauge on it they either should turn off automatically when voltage drops or have a seperate remote trigger.