Connecting amp to two batteries...dual inputs required?

[99Eternal]

EDIT: I found a good tutorial on here. http://www.caraudio.com/forums/wiring-electrical-installation-help/398527-dual-battery-wiring-tutorial-why.html

It answered my questions. I didn't understand why 2 fuses are required in between the two batteries, I would think one would pop breaking the circuit.

Someone had said because if one end comes out of a fuseholder, it could start a fire. I see how that is added safety. But on the other hand, even with the second fuse, if the wire on the battery side of the fuseholder came loose, you'd have a fire, and with two fuses there's double the connections that could come loose. I guess in the end it's still slightly safer.

Hey everyone, my first post here.

I am about to start upgrading my electrical in preparation for my two DC level 4 15's on a 3.5k, and I have a few questions.

I've searched through many threads on this topic but I can't seem to find an answer.

**Chevy puts the battery in the trunk** in the cobalt which I have already replaced with an XS D3400 around a year ago and I plan to add a second D3400(or possibly a larger one), as well as upgrade my alt to a 240+ with all 1/0 wire.

I'd like to confirm the connections for both the alt to the batterys, and ask about connecting the amp to the two batteries.

From what I understand for alt to battery I would:

1) do two fused @ 300a (+) runs of 1/0 from the alt, one going to each + on the battery.

2) jumper the batteries, + to +, - to - with a 300a fuse on just the positive jumper? or negative jumper as well?.

3) ground both batteries to the frame. but do I go from each (-) battery post to frame? I assume so but would like confirmation.

4) make sure all my factory grounds are upgraded to 1/0.

Then for the amp...I think I understand how dual inputs would work. each battery positive would go to one of the inputs on amp, same with negatives? Is that right?

What I really don't understand is, if i wanted to do this without dual inputs, how I would connect the 2 batteries to the amp? Just pick a battery? I am sure I have seen multiple batteries with only 1 + and - neg input. I just can't wrap my head around it. Eventually I will probably do dual inputs anyways but I want to understand this before I put power to my new equipment!

Thanks for any help!

Edited August 16, 2012 by 99Eternal

[Chris Hammer]

Just connect the amp to a positive terminal on one battery and connect the negative to the negative. Dual inputs can be beneficial but not really unless you are pushing the limits. As long as you have all the positives wired together and wired to the battery up front and all negative toghether and to a ground or dedicated run to the front..you are good.

[99Eternal]

Just connect the amp to a positive terminal on one battery and connect the negative to the negative. Dual inputs can be beneficial but not really unless you are pushing the limits. As long as you have all the positives wired together and wired to the battery up front and all negative toghether and to a ground or dedicated run to the front..you are good.

Alright. But see I don't have a battery up front. As mentioned, Chevy Cobalt stock batt location is in the trunk. So it will only be 2 batteries totaI. Most of the info i can find on this is with a starting battery up front. I know electrically the connections should be the same, just want some confirmation. I am starting to think I was wrong about doing a run from alt to each battery postive. http://www.stevemead..._1#entry1980603

according to that thread I should be connecting my alt to only one battery? and then link that battery to the second, and connect the amp to the second batt? That seems logical I suppose..any input?

EDIT - I think i was wrong in first post saying 1 pos run to each battery. I thought that was the point of two runs, to give even alt power to each battery but now I am starting to think it's just to effectively double the size of your wire. Is that correct? Is 1 run to each batt pos from the alt a no-no? I'd love some more input on this...I'm mentally exhausted from work and just can't get this straight in my head.

Edited August 16, 2012 by 99Eternal

[07denali]

Wire the batteries in parallel and only hook one up to the amp. Dual inputs is for when you are running multiple runs of wires.

[99Eternal]

Wire the batteries in parallel and only hook one up to the amp. Dual inputs is for when you are running multiple runs of wires.

Thanks I think i'm good now. One thing - when you say dual inputs are for multiple runs of wires, do you mean from the battery to the amp, or from the alt to the batteries? Or both?

I ask because I am debating 1 or two runs of 1/0 from alt to batteries, I could still run just 1 pos and 1 neg to the amp without issue, correct?

[07denali]

From battery to amp. You generally don't need multiple runs of wire for your alternator but it doesn't hurt. I would suggest having someone with a little more knowledge help you.

Multiple runs are needed when your system exceeds the capacity of the wire you are running. For big systems, say 10,000 watts, and let's say voltage is 14 volts, that's 714 amps. Your 0 gauge has a capacity of about 300 amps, assuming it's decent OFC wire. So you will need at least two runs of 0 gauge, but preferably three, in order to move the power your system requires. You should be fine with one run with the 3.5K.