Do you think i should add a extra baterry for my car audio build?

Booker Warlick: I'm not into car audio, but I have seen and helped friends install them.One system was a 25 pound Harmon Kardon amp unit that demanded so much power that the manufacturer specified a second battery and second alternator. I've see friends with extra dry cell batteries in the trunk to adequately power their bass sub-woofers. If you choose a second system, the challenge is getting a second bracket mounted in front of the engine and routing a belt over to it to drive it. The circuit MUST be independent from the primary car battery for reasons that should be obvious - except they can share a common ground. If you attempt to use two batteries on the same circuit, remember to keep the circuits in parallel (not in series, lest you inadvertently bump the voltage from 12 to 24VDC and fry your audio and auto computer electronics).Getting a bigger battery is an awesome idea - IF IT WILL FIT. You'll have 12 volts and tons of amps to drive everything. A minor downside! is your alternator will be stressed, so anticipate replacing it on a shorter service interval. (I like to replace starters and alternators on a standard schedule as a point of maintenance. Better to replace them when you can in a controlled situation than be stranded and at the mercy of a hungry mechanic 100 miles from home).An single alternator that outputs 240 amps is about as impressive as I've ever heard of. The battery will be more than that, so you should be good. You devices should be current limiting on their own.You should discuss this with a good technician (one who graduated from an electronics school) who can do the math, or consult an electrical engineer and go through your components. If you're tricking out your ride with sound, likely you're adding under-carriage neon lightings too.You have a lot of options and other issues to address as well, but you probably know all that.It sounds like a fun project -- best wishes, hope it works out for you....Show more