has anyone added a 2nd battery? got a DIY?

when do you actually need to be running a 2nd battery? ive got a 600 watt amp for the sub and a 300 for speakers. do i need it? anything i should be worried about? can you just change to a more powerful alternator...and umm. what exactly does an alternator do? im about to check out www.howstuffworks.com right now.

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A second battery would be useful for running the stereo system with the engine off. You could isolate it from the main battery, and that way if you drained it, you could still start your car and drive home.

If your stereo system draws too much current for the car to handle in stock form, even with the engine on, you'll need a heavier-duty alternator, not a battery.

 

I have a SVR second battery. It powers my 2 500/1 amps, 1 300/4, 2 12" subs and is mounted in the trunk. I don't have a DIY though, I didn't do it. I put it in because I was having voltage fluctuation in the headlights and interior lights. I felt my system was draining to much factory battery. All better now.

IP / 6MT / Xenons Everywhere / Mirror Tint / Injen CAI / Injen Exhaust / Tanabe Springs / Ground Wires / Apex'i S-AFC II / Some things you don't know about yet!

 

Adding a second battery without an isolator and not upgrading you alternator can damage your electrical system. The second battery is seen as an additional load to the alternator, and most alternators do not have enough headroom to support such a load. If you lights are dimming the best bet is to upgrade your alternator, or as a band-aid upgrade your stock battery to something like an Optima, or install a big cap.



Kevin
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04 Diamond Graphite Coupe - FULLY loaded
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The isolator is important, because without it, if one battery dies, it'll drain the other battery just for extra fun!

 

Without an isolator both batteries will discharge at the same rate (assuming they are wired in parallel). The draining of one battery will not drain the other battery due to the fact that they will both die at the same time. With two batteries wired in parallel you will have the same voltage potential, but you will have the sum of each individual batteries current output. So, if you have a battery with 800cca and a battery with 600cca you will end up with 1400 cca. The reserve, since it is current based, works the same way, just add them together.




Kevin
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04 Diamond Graphite Coupe - FULLY loaded
Windows up with OEM Remote
RE Short Shifter // Z Tube

 

Okay, I was close. You need the isolator so that if you're running your radio with the engine off, it only drains one of the batteries, not both.... [img]/w3timages/icons/smile.gif[/img]

 

I have an isolator as well. I just didn't mention it. I also upgraded the wiring to the stock alternator.

IP / 6MT / Xenons Everywhere / Mirror Tint / Injen CAI / Injen Exhaust / Tanabe Springs / Ground Wires / Apex'i S-AFC II / Some things you don't know about yet!

 

I am using 2, 1 Farad Capacitors. I have 1300 total watts and even with the caps they do not last too long with the car off and jamming the radio out for 10 minutes. Now it is a different story when you have the car on. The caps will help give you extra bursts of energy to the subs and speakers when needed, unlike a conventional battery. Try on a cap or two for size and see if it will help your application.

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